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751 articles found

E0325 – The role of Nb in the formation of sulphonic species in SBA-15 and MCF functionalised with MPTMS

Mesoporous silica and niobiosilicate materials of SBA-15 and MCF types were prepared in the presence of MPTMS, i.e. (3-mercaptopropyl)trimethoxysilane and hydrogen peroxide. The samples obtained were characterised by different techniques (N2 adsorption/desorption, XRD, elemental and thermal analyses) and applied as catalysts in glycerol esterification with acetic acid. The role of niobium species on the formation of sulphonic species and stability of organosilane modifier was explored. The most important finding is that the addition of niobium to the synthesis gel improves the efficiency of –SH oxidation by hydrogen peroxide towards sulphonic species. This behaviour is not dependent on the type of structure of mesoporous materials (SBA-15 or MCF). However, the kind of mesoporous solid influences the efficiency of Nb incorporation and on the esterification process. MCF matrix improves the catalytic performance of the MPTMS modified catalyst.
Maciej Trejda, Katarzyna Stawicka, Maria Ziolek, Catalysis Today 192 (2012) 130– 135

E0236 – Influence of the nature and porosity of different supports on the acidic and catalytic properties of H3PW12O40

In order to obtain highly dispersed heteropolyacid (HPA) species, H3PW12O40 was supported on various supports exhibiting different porosities and surface chemical properties. Amorphous and monoclinic amphoteric zirconias, activated montmorillonite (AC) and hexagonal silica (HMS) were chosen as supports. It was observed that the zirconia support partly decomposed HPA at low coverage, giving the lacunary anion PW11O7?39 , due to the reaction with basic hydroxyl groups, whereas montmorillonite and HMS did not. Catalytic properties for n-butane to isobutane isomerisation at 473 K and propan-2-ol decomposition at 353 K were compared for all samples as a function of HPA loadings and compared to data already published on bulk H3PW12O40 and Cs1.9H1.1PW12O40 samples. It was found for HPA/AC samples that, although their activity for propan-2-ol decomposition varied linearly with HPA loading, their activity for n-butane isomerisation was very weak, which indicates a weaker acid strength by supporting the HPA. This is probably due to the exchange of protons from the HPA by the exchangeable cations of the montmorillonite, the new protons associated with the clay being much less acidic. It also appeared, when comparing with catalytic data already published on for HPA/HMS, that HMS was the best support for HPA without modifying appreciably its catalytic and thus their acid properties, the HPA being certainly bonded to the HMS walls by hydrogen bonding. Assuming a diameter of 1.2 nm for each Keggin anion, the turnover frequency (TOF) values for n-butane isomerisation at 473 K were calculated per surface Keggin species for HPA/HMS, bulk H3PW12O40 and Cs1.9H1.1PW12O40, and were found to be equal to 155, 113 and 100 × 10?5 s?1, respectively, and thus to be very close, showing that the acid strength of the three samples was comparable. It was found to equal only 3.4×10?5 s?1 for the HPA/AC sample, in agreement with a weaker acid strength. At last, mesoporosity of the support was found to favour n-butane isomerisation reaction.
Cédric Trolliet, Gisèle Coudurier, Jacques C. Védrine, Topics in Catalysis Vol. 15, No. 1, 2001

E0128 – Selective oxidation of methanol to formaldehyde over V-Mg-O catalysts

The results of a complex investigation of V-Mg-O catalysts for oxidative dehydrogenation (ODH) of methanol are presented. The efficiency of vanadium-magnesium oxide catalysts in production of formaldehyde has been evaluated. Strong dependence of the formaldehyde yield and selectivity upon vanadium oxide loading and the conditions of heat treatment of the catalyst were observed. The parameters of the preparation mode for the efficient catalyst were identified. In optimised reaction conditions the V-Mg-O catalysts at the temperature approximate 450°C ensured the formation of formaldehyde with the yield of 94% at the selectivity of 97%. No visible changes in the performance of the catalyst (methanol conversion, formaldehyde yield and selectivity) were detected during the 60 h of operation in prolonged runs. Characterization of the catalyst by XRD, IR, and UV methods suggests the formation of species of the pyrovanadate type (Mg2V2O7) with irregular structure on the surface of a V-Mg-O catalyst. These species make the catalyst efficient for methanol ODH.
G.V. Isaguliants, I.P. Belomestnykh, Catalysis Today 100 (2005) 441-445

B3319 – Structural properties of alumina- and silica-supported Iridium catalysts and their behavior in the enantioselective hydrogenation of ethyl pyruvate

Iridium catalysts were prepared using alumina or silica as supports and two preparation methods, incipient wetness impregnation and flame spray pyrolysis. These catalysts were characterized, after reduction in hydrogen, by transmission electron microscopy, infrared spectroscopy of adsorbed CO and microcalorimetry of CO chemisorption. Aliquots of these catalysts were tested in the ethyl pyruvate hydrogenation using cinchonidine as a chiral modifier. Different enantioselectivities to (R)-ethyl lactate were obtained depending on the support material and the preparation method. Based on the structural characterization it is proposed that the different enantioselectivities are mainly due to different surface structure of the iridium nanoparticles caused by the support interaction.
A.B. Dongil, B. Bachiller-Baeza, I. Rodríguez-Ramos, A. Guerrero-Ruiz, C. Mondelli, A. Baiker, Applied Catalysis A: General 451 (2013) 14– 20

B3318 – Modulation of the acidity of niobic acid by ion-doping: Effects of nature and amount of the dopant ions

The acidity of niobic acid (NBO) has been successfully mitigated and tuned by addition of K+, Ba2+ and Nd3+ dopant species in amounts from 1 to 15 atom nm?2. The characterization of the intrinsic acid properties of the samples was performed by adsorption of NH3 in a volumetric–microcalorimetric coupled line and by temperature programmed desorption (TPD) of 2-phenylethylamine in a thermogravimetric apparatus. The K-dopant was more effective in decreasing the acidity of niobic acid than the Ba- and Nd-dopants. Complementary measurements of the effective acidity of the samples in water by base titrations with 2-phenylethylamine completed the study and revealed a different picture of the effect of the three dopants on the NBO acidity in water. All the results indicated that the K-dopant targeted more selectively the Brønsted acid sites, acting as an ion-exchanger, while Ba- and Nd-species predominantly acted on the Lewis acid sites of the NBO surface
Paolo Carniti, Antonella Gervasini, Matteo Marzo, Aline Auroux, Thermochimica Acta 567 (2013) 51– 56

B3317 – Hydrothermal synthesis and characterization of zirconia based catalysts

In this work, three equimolar mixed oxides ZrO2/CeO2, ZrO2/TiO2, ZrO2/La2O3 and a reference ZrO2 have been synthesized by hydrothermal method. The structural and surface properties of these materials have been fully characterized by X-ray diffraction, transmission electron microscopy, surface area measurement, chemical analysis, XPS, infrared spectroscopy after adsorption of pyridine and adsorption microcalorimetry of NH3 and SO2 probe molecules. All investigated mixed oxides are amphoteric and possess redox centers on their surface. Moreover, hydrothermal synthesis leads to catalysts with higher surface area and with better acid–base properties than classical coprecipitation method. Both Lewis and Brønsted acid sites are present on the surface of the mixed oxides. Compared to the other samples, the ZrO2/TiO2 material appears to be the best candidate for further application in acid–base catalysis.
T. Caillot, Z. Salama, N. Chanut, F.J. Cadete Santos Aires, S. Bennici ,A. Auroux, Journal of Solid State Chemistry 203 (2013) 79–85

B3311 – Selective oxidation of glycerol with O2 catalyzed by low-cost CuNiAl hydrotalcites

A series of CuNiAl hydrotalcites (HTs) were prepared and used to the selective oxidation of glycerol with O2. The results revealed that elemental composition, structures and the surface properties of the obtained catalysts significantly influenced their catalytic performance. Among them, amino-functionalized CuNiAl-HTs showed excellent catalytic performance due to their enhanced surface Lewis basicity. Under the optimal reaction conditions, the highest conversion of glycerol reached 68.1% with 76% of the selectivity to glyceric acid; moreover, the catalytic performance remained after being recycled 6 times.
Gongde Wu, Xiaoli Wang, Yuan Huang, Xianfeng Liu, Fang Zhang, Keqiang Ding, Xiaolan Yang, Journal of Molecular Catalysis A: Chemical 379 (2013) 185– 191

B3310 – Interaction of CO probe molecules with Cu(+) in MCM-22 zeolite

The interaction of CO probe with copper exchanged MCM-22 zeolite is studied. Particularly, the heterogeneity of Cu(+) ions is examined. For this purpose, combined CO adsorption microcalorimetry with FTIR of CO adsorption/desorption at RT and elevated temperature is originally exploited. Contribution brings the first experimental evidence for three families of Cu(+) ions differing in the interaction energy with CO and exhibiting Qdiff around 107, 100 – 97 and ?92 kJ mol?1, respectively. The energy distribution determined from calorimetry and desorption curves is due to copper coordination differences. Despite wide energetic distribution of carbonyls, only two bands in IR spectra at 2159 and 2150 cm?1 are observed. Similarly to other zeolites, Cu(+) loses its original coordination to framework during the CO adsorption. The preferred trigonal planar geometry with CO and two zeolite oxygen gives rise to the band at 2159 cm?1. Peculiarly for MCM-22, significant amount of Cu(+) ions stay three-coordinated to the zeolite after CO adsorption, relate to mediate interaction energies and correspond to the band at 2150 cm?1. Characteristic changes on the IR spectrum revealed that the enhanced movement of ions after CO exposure occurs at higher temperature. The influence of zeolite composition, namely Cu loading and Si/Al ratio, on the character of IR spectrum and population of energetic components is discussed.
Karel Frolich, Roman Bulánek, Eva Frýdová, Microporous and Mesoporous Materials (2013)

B3308 – Effect of hydrogen on the cracking mechanisms of cycloalkanes over zeolites

Hydrocracking of secondary interest refinery streams (high aromatic content) can yield valuable products for transportation and petrochemical industry. In order to promote the hydrogenation and cracking steps, a bifunctional catalyst (metal + acid function) is required. We have studied the effect of the operating conditions on cycloalkane (product of aromatic hydrogenation) ring opening over a monofunctional HZSM-5 zeolite, by focusing on the effect of hydrogen in the cracking mechanisms. Methylcyclohexane has been selected as the test reactant and the conditions used corresponds to temperature, 250–450 °C; space velocity, 0.7–1.1 h?1; pressure, 2–80 bar; hydrogen/methylcyclohexane molar ratio, 1–79; conversion, 0–100% (integral reactor). At these conditions the zeolite catalyses hydrogenation as well as cracking (bifunctional capabilities), thus the cracking mechanisms are directly affected by hydrogen as products (alkenes) and intermediates (carbenium ions) are saturated. The overall effect of rising hydrogen partial pressure is an enhancement of (hydro)isomerization and monomolecular cracking, that is, an increase of the yield/selectivity of methane, ethane, penthane and isoalkanes.
Pedro Castano, José M. Arandes, Martin Olazar, Javier Bilbao, Barbara Pawelec, Ulises Sedran, Catalysis Today 150 (2010) 363–367

B3307 – Solid acid catalysts based on H3PW12O40 heteropoly acid: Acid and catalytic properties at a gas–solid interface

Solid acid catalysts prepared by supporting 15 wt%H3PW12O40 heteropoly acid (HPA) on TiO2, ZrO2 and Nb2O5 with a sub-monolayer HPA coverage were characterised at a gas–solid interface, regarding their acid properties and chemical structure of HPA on the catalyst surface and compared to “standard” HPA catalysts such as bulk and silica-supported H3PW12O40 and Cs2.5H0.5PW12O40. In contrast to the parent acid, H3PW12O40, possessing strong Brønsted acid sites, the catalysts supported on TiO2, ZrO2 and Nb2O5 have both Brønsted and Lewis acid sites, with the latter mainly originating from the oxide support. The strength of acid sites in these catalysts is weaker than that in H3PW12O40 and Cs2.5H0.5PW12O40. The catalytic activity (turnover frequency) in gas-phase isopropanol dehydration decreases in the order: H3PW12O40 > Cs2.5H0.5PW12O40 > 15%H3PW12O40/SiO2 > 15%H3PW12O40/TiO2 > 15%H3PW12O40/Nb2O5 > 15%H3PW12O40/ZrO2, which is in line with the acid strength as determined by NH3 adsorption calorimetry. Ammonia adsorption calorimetry, 31P{1H} MAS NMR and FTIR indicate increasing interaction between support and HPA in the following order of supports: SiO2 < TiO2 < Nb2O5 < ZrO2.
Ali M. Alsalme, Paul V. Wiper, Yaroslav Z. Khimyak, Elena F. Kozhevnikova, Ivan V. Kozhevnikov, Journal of Catalysis 276 (2010) 181–189

B3306 – Kinetic Modeling of n-Butane Cracking on HZSM-5 Zeolite Catalyst

A kinetic model of lumps has been established for n-butane cracking over HZSM-5 zeolite catalyst (SiO2/Al2O3 = 30) in the 400?550 °C range, based on the results obtained in a fixed bed reactor (space time, up to 2.4 (g of catalyst) h (mol CH2)?1; He/n-butane molar ratio in the feed, up to 6/1; time on stream, 5 h). The model allows quantifying the distribution of the lumps of products (C2?C4 olefins, C2?C4 paraffins, methane, and C5?C10 components) in a wide range of temperatures, partial pressures of hydrocarbons in the reaction medium, and space times. The kinetic model steps for the transformation of n-butane into olefins and of olefins into paraffins and C5?C10 are second order with respect to the reactant, whereas the remaining steps are first order with respect to each reactant. When the target is the production of C2?C4 olefins, the yield is limited to 12%, at 550 °C.
Diana Mier, Andres T. Aguayo, Monica Gamero, Ana G. Gayubo, Javier Bilbao, Ind. Eng. Chem. Res. 2010, 49, 8415–8423

B3290 – In situ studies of structure–reactivity relations in biodiesel synthesis over nanocrystalline MgO

High temperature processing of solvothermally synthesised MgO nanoparticles promotes striking changes in their morphology, and surface chemical and electronic structure. As-prepared NanoMgO comprised ?4 nm cubic periclase nanocrystals, interspersed within an amorphous Mg(OH)(OCH3) matrix. These crystallites appear predominantly (1 0 0) terminated, and the overall material exhibits carbonate and hydroxyl surface functionalities of predominantly weak/moderate base character. Heating promotes gradual crystallisation and growth of the MgO nanoparticles, and concomitant loss of Mg(OH)(OCH3). In situ DRIFTS confirms the residual precursor and surface carbonate begin to decompose above 300 °C, while in situ XPS shows these morphological changes are accompanied by the disappearance of surface hydroxyl/methoxide species and genesis of O? centres which enhance both the surface density and basicity of the resulting stepped and defective MgO nanocrystals. The catalytic performance in tributyrin transesterification with methanol is directly proportional to the density of strong surface base sites.
Janine M. Montero, D. Rob Brown, Pratibha L. Gai, Adam F. Lee, Karen Wilson, Chemical Engineering Journal 161 (2010) 332–339

B3288 – Activation of dihydrogen on supported and unsupported silver catalysts

The activation of dihydrogen on silica, silver, and silica-supported silver (9 wt% Ag) was investigated. Both silica and silver are individually able to dissociate dihydrogen. Silanol groups on silica undergo H ? D exchange at 393 K in D2 as detected by IR spectroscopy. HD is observed in temporal analysis of products (TAP) experiments when H2 and D2 are sequentially pulsed on silver at 673 K; even when the time delay between the isotopes is 4 s, HD is formed, indicating that long-lived surface hydrogen species are present. Differential scanning calorimetry (DSC) shows that the activation of dihydrogen is an activated process: heat signals evoked through H2 pulses on Ag/SiO2 grow with increasing temperature (373–523 K). Nonetheless, the presence of silver on the silica surface accelerates the Si–OH ? Si–OD exchange. Investigation of the exchange kinetics on Ag/SiO2 shows that diffusion processes of the activated hydrogen species are rate determining at higher temperatures (?373 K), when the activation of D2 on silver becomes facile. Indications of diffusion limitation are observed already at 313 K on Pt/SiO2. TAP and DSC measurements show that H2 is more readily activated on silver that has been treated in O2 at 673 K followed by reduction in H2 at 673 K. Morphological changes induced to the silver surfaces or (sub)surface oxygen species are presumed responsible for this effect.
J. Hohmeyer, E.V. Kondratenko, M. Bron, J. Kröhnert, F.C. Jentoft, R. Schlögl, P. Claus, Journal of Catalysis 269 (2010) 5–14

B3285 – Model reactions as probe of the acid–base properties of aluminas: Nature and strength of active sites. Correlation with physicochemical characterization

Acetonylacetone conversion at 250 and 350 °C was carried out over various transition aluminas (?- to ?-Al2O3) in order to estimate simultaneously their acid–base properties. The formation of 2,5-dimethylfuran (DMF) was associated to the presence of acid site, and the formation of 2-methyl-3-cyclopenten-1-one (MCP) associated to basic site. First, from carbon dioxide adsorption measurement, hydroxyl basic group was found to be the active site for MCP formation and 2,6-dimethylpyridine (DMP) adsorption measurement shows that Brønsted acid site is active site for DMF formation. Secondly, from catalytic results, we show that ?-Al2O3 possesses a basic/acid ratio (MCP/DMF = 16) higher than the other aluminas (MCP/DMF < 10), and from comparison with cyclopentanol/cyclohexanone mixture transformation (acid alcohol dehydration and acid–base hydrogen transfer between alcohol and ketone), we also show that acetonylacetone cyclization are a more difficult reaction. Finally, the combination of model reactions and CO2 and DMP adsorption allows us to propose a description of the nature and the strength of the various aluminas surface.
Sonia Carre, Benoit Tapin, Ngi Suor Gnep, Renaud Revel, Patrick Magnoux, Applied Catalysis A: General 372 (2010) 26–33

B3255 – Flow calorimetry and adsorption study of dibenzothiophene, quinoline and naphthalene over modified Y zeolites

The adsorptive removal of dibenzothiophene (DBT), quinoline and naphthalene in hexadecane on the zeolites, NaY, NiY and CsY, using liquid phase flow calorimetry and adsorption experiments, was studied at 30 °C. NiY and CsY were prepared by the liquid phase ion-exchange method. The adsorbents were characterized by XRD, BET surface area, elemental analysis (ICP-OES) and DRIFT spectroscopic techniques. The adsorption experiments were carried out by equilibrium adsorption and flow calorimetry techniques. Modification of NaY zeolite with Ni and Cs salts resulted in the partial amorphotization of the zeolite structure which affected the adsorption properties. A higher heat of adsorption was determined for quinoline compared to DBT and naphthalene and a preferential adsorption of quinoline in a mixture containing quinoline, naphthalene and DBT was observed on NaY, NiY and CsY. The adsorption of quinoline on NiY possibly involved a direct end-on ? interaction of the Ni2+ with the lone pair of electrons of the N atom on quinoline while the adsorption of DBT and naphthalene occurs via a ? interaction of the d orbitals of Ni2+ with the electrons in the aromatic rings. The equilibrium adsorption capacity of NaY was found to be the highest among the three zeolites. The decrease in the adsorption capacities of NiY and CsY appears to result mainly from the partial collapse of the zeolite structure during the ion-exchange process
J. Keir Thomas, Kamalakar Gunda, Peter Rehbein, Flora T.T. Ng, Applied Catalysis B: Environmental 94 (2010) 225–233

B3254 – Synthesis and characterization of ultramicroporous silica xerogels

Tailoring the porous texture of silica xerogels is of great interest in catalysis, adsorption and sensors. We report the preparation and characterization of xerogels with pore size distribution lower than 0.5 nm, synthesized by hydrolysis and condensation of tetraethylorthosilicate (TEOS) at pH 2.5. N2 (77 K) and CO2 (273 K) adsorption isotherms and immersion calorimetry into liquids with different molecular size (dichloromethane, 0.33 nm; trichloromethane, 0.40 nm; n-hexane, 0.43 nm; cyclohexane, 0.48 nm; isooctane, 0.59 nm; and carbon tetrachloride, 0.66 nm) were used to characterize ultramicroporous xerogels. All the xerogel samples adsorbed CO2 (273 K) but not N2 (77 K). Pore size distributions from immersion calorimetry showed that hydrolysis and condensation of TEOS at pH 2.5 produced silica xerogels with pore size distributions in the 0.33–0.48 nm range. Xerogels synthesized at 333 K and a 5.5:1 water:TEOS molar ratio produced xerogels with higher specific surface areas and wider pore size distributions than xerogels obtained at 293 K and at 2.5:1 water:TEOS molar ratio
Jesús C. Echeverría, Juncal Estella, Vanesa Barbería, Javier Musgo, Julián J. Garrido, Journal of Non-Crystalline Solids 356 (2010) 378–382

B3253 – The effect of surface acidic and basic properties on the hydrogenation of aromatic rings over the supported nickel catalysts

Ni/Al2O3, Ni/MgAlO and Ni/MgO catalysts containing about 60 wt% of nickel were prepared by the co-precipitation method. The textural and structural properties were characterized and it was found that the dispersion of nickel was high in these catalysts. The active nickel surface area was found to be high (78 m2/gcat.) in Ni/MgAlO, corresponding to the average nickel particle size of 3.5 nm. Microcalorimetric adsorption of NH3 and CO2 showed that the Ni/Al2O3 and Ni/MgO exhibited strong surface acidity and basicity, respectively, while the Ni/MgAlO possessed both surface acidity and basicity. In addition, both the initial heat and coverage were higher on Ni/Al2O3 than on Ni/MgO for the adsorption of toluene, indicating the strong interaction between the aromatic rings in toluene (that may act as a Lewis base due to the enriched electron densities) and the surface acidic sites on the support. The adsorption of toluene on the metallic nickel surface produced higher heat, indicating the strong interaction of the ? electrons in aromatic rings of toluene with the d orbitals of surface nickel atoms. Although the adsorption of H2 showed the higher active surface nickel area in Ni/MgAlO than in Ni/Al2O3, the activities of hydrogenation of toluene and phenol were significantly higher on Ni/Al2O3 than on Ni/MgAlO, indicating the important effect of surface acidity on the hydrogenation of aromatic rings.
Shenghua Hu, Mingwei Xue, Hui Chen, Jianyi Shen, Chemical Engineering Journal 162 (2010) 371–379

B3252 – Mechanistic investigation of hydrothermal aging of Cu-Beta for ammonia SCR

The selective catalytic reduction of NOx with NH3 over a Cu-BEA catalyst was studied after hydrothermal aging between 500 and 900 °C. The corresponding catalyst was characterized using XPS and XRD techniques in the aging interval of 500, 700 and 800 °C. No structural changes during the aging process were observed. However, the oxidation state of copper changed during aging and more Cu2+ was formed. We suggest that one of the deactivation mechanisms is the decrease of the Cu+ species. The NO oxidation and NH3 oxidation activity was decreased with increasing aging temperature. Further, we observed that the ammonia oxidation was decreased faster compared to the SCR reactions at low aging temperatures. The experiments from the calorimeter as well as from the ammonia TPD investigations indicate a trend towards more weakly bound ammonia with higher aging temperatures. From the results of the SCR experiments using different NO2/NOx ratios and ammonia oxidation experiments we suggest that most of the N2O is coming from side reactions of the SCR mechanism and not from reactions between NH3 and O2 alone. Interestingly, we observe that after the 900 °C aging a quite large activity remained for the case with 75% NO2/NOx ratio. The N2O production shows a maximum at 200 °C, but increases again at higher temperatures. However, the N2O formed at low temperature is decreased after hydrothermal aging while the high temperature N2O is increased. We propose that the different reactions examined in this work do not all occur on the same type of sites, since we observe different aging trends for some of the reactions.
Norman Wilken , Kurnia Wijayanti , Krishna Kamasamudram , Neal W. Currier , Ramya Vedaiyan, Aleksey Yezerets, Louise Olsson, Applied Catalysis B: Environmental 111– 112 (2012) 58– 66

B3251 – Chemical deactivation by phosphorous under lean hydrothermal conditions over Cu/BEA NH3-SCR catalysts

To obtain a better understanding of the deactivation of SCR catalysts that may be encountered due to the presence of P-containing impurities in diesel exhausts, the effects induced by P over Cu/BEA NH3-SCR catalysts were studied as functions of the temperature of poisoning and P concentration in the feed. Cu/BEA catalysts with different Cu loadings (4 and 1.3 wt% Cu) were exposed to P by controlled evaporation of H3PO4 in the presence of 8% O2 and 5% H2O at 573 and 773 K. The reaction studies were performed by NH3-storage/TPD, NH3/NO oxidation and standard NH3-SCR. In addition, a combination of several characterisation techniques (ICP–AES, BET surface area, pore size distribution, H2-TPR and XPS) was applied to provide useful information regarding the mechanism of P deactivation. Pore condensation of H3PO4 in combination with pore blocking was observed. However, the measured overall deactivation was found to occur mostly by chemical deactivation reducing the number of the active Cu species and hence deteriorating the redox properties of the Cu/BEA catalysts. The process of P accumulation on the surface preferentially occurs on the “over exchanged” Cu active sites with the formation of phosphate species. This is likely the reason for the more severe deactivation of the 4% Cu/BEA compared to 1.3% Cu/BEA. Further, the higher NOx reduction performance at 773 K of the P-poisoned Cu/BEA catalysts was found to originate from the lower selectivity towards NH3 oxidation, which occurs predominately on the “over-exchanged” sites.
Stanislava Andonova, Evgeny Vovk, Jonas Sjöblom, Emrah Ozensoy, Louise Olsson, Applied Catalysis B: Environmental 147 (2014) 251– 263

B3237 – Spark plasma sintering synthesis of Ni1?xZnxFe2O4 ferrites: Mössbauer and catalytic study

Nickel-zinc ferrite nanoparticles, Ni1 xZnxFe2O4 (x ¼ 0, 0.2, 0.5, 0.8, 1.0) were prepared by combination of chemical precipitation and spark plasma sintering (SPS) techniques and conventional thermal treatment of the obtained precursors. The phase composition and structural properties of the obtained materials were investigated by X-ray diffraction and Mössbauer spectroscopy and their catalytic activity in methanol decomposition was tested. A strong effect of reaction medium leading to the transformation of ferrites to a complex mixture of different iron containing phases was detected. A tendency of formation of Fe-carbide was found for the samples synthesized by SPS, while predominantly iron-nickel alloys ware registered in TS obtained samples. The catalytic activity and selectivity in methanol decomposition to CO and methane depended on the current phase composition of the obtained ferrites, which was formed by the influence of the reaction medium.
Nikolay Velinov, Elina Manova, Tanya Tsoncheva, Claude Estournès, Daniela Paneva, Krassimir Tenchev, Vilma Petkova, Kremena Koleva, Boris Kunev, Ivan Mitov, Solid State Sciences 14 (2012) 1092-1099

B3219 – CO2 adsorption on carbon molecular sieves

The effect of the textural properties of a series of commercial carbon molecular sieves (CMS), prepared from different polymeric precursors, on their ability for CO2 adsorption at different temperatures has been studied. The adsorbents have been characterized by N2 and CO2 adsorption at 77 and 273 K, respectively, together with measurements of immersion calorimetry into liquids of different molecular dimensions. The studied CMSs cover a wide range of porosity, from purely microporous carbons to samples containing wide micropores as well as a certain proportion of mesoporosity. Studies of CO2 adsorption, at atmospheric pressure (1 bar) and three different temperatures (273, 298 and 323 K), have shown that a high CO2 adsorption capacity requires the presence of a well-developed microporosity, as well as a high volume of narrow micropores. On the other hand, narrow micropores seem to be the key factor leading to a maximum capacity of CO2 adsorption, even at temperatures close to that of anthropogenic emissions of CO2.
A. Wahby, J. Silvestre-Albero, A. Sepúlveda-Escribano, F. Rodríguez-Reinoso, Microporous and Mesoporous Materials 164 (2012) 280–287

B3218 – Structure–activity relationships of simple molecules adsorbed on CPO-27-Ni metal–organic framework: In situ experiments vs. theory

In this work we review experimental XRPD, EXAFS, Raman, IR, microcalorimetric data on the adsorption of H2O, NO, CO, CO2, N2, C2H4 and H2 molecules on CPO-27-Ni material, a metal–organic framework (MOF) showing a coordination vacancy at the Ni2+ site in its desolvated form. Literature data are complemented by few new experimental results. A systematic theoretical study performed at the B3LYP-D*/TZVP level of theory (using a periodic boundary conditions) allowed us to reach a complete understanding of the structural, vibrational and energetic features of the material in interaction with the different molecules obtained from the different experimental techniques. From both experimental and theoretical set of data, interesting trends have been obtained for the framework distances (Ni–O and Ni–Ni) and frequency shifts of the framework vibration modes as a function of the adsorption energy (enthalpy) of the different probe molecules. This multitechnical approach, already applied for UiO-66 MOF is of general validity and can be straightforwardly extended to all MOF materials.
L. Valenzano, J.G. Vitillo, S. Chavan, B. Civalleri, F. Bonino, S. Bordiga, C. Lamberti, Catalysis Today 182 (2012) 67– 79

B3216 – Glycerol dehydration over calcium phosphate catalysts: Effect of acidic–basic features on catalytic performance

This work focuses on investigation of calcium phosphate compounds with different Ca/P ratios (1.39–1.77). Additionally, hydroxyapatite impregnated with tungsten oxide was also investigated. The structural, textural, and surface properties of these materials have been fully characterized using appropriate techniques (low-temperature adsorption–desorption of nitrogen, X-ray diffraction analysis (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and temperature-programmed reduction (TPR)). Adsorption microcalorimetry of NH3 or SO2 was used to estimate the population, strength and strength distribution of acid and basic sites. The nature of acidic sites was determined through the adsorption/desorption of pyridine, followed by infrared spectroscopy. Catalytic performance of the catalysts was tested in the gas phase dehydration of glycerol with the intention of finding correlations between catalytic activity and surface acid–base features. Results show that Ca/P ratio, beside the already known influence on acidic/basic features, also influences red-ox properties of these materials. The investigation performed here proved that, in order to get acrolein – with high selectivity – which is formed on acid sites, it is not only necessary to provide acidity, but also to hinder basic sites. Our results also show that reducing of number and strength of acid centers increases the yield of other desired product, acetol.
Dusan Stosic, Simona Bennici, Sergey Sirotin, Christophe Calais, Jean-Luc Couturier, Jean-Luc Dubois, Arnaud Travert, Aline Auroux, Applied Catalysis A: General 447– 448 (2012) 124– 134

B3215 – Step-by-step design of novel biomimetic nanoreactors based on amphiphilic calix[4]arene immobilized on polymer or mineral platforms for destruction of ecological toxicants

The effective supramolecular catalysts based on amphiphilic calix[4]arene functionalized by iso-nonyl groups at the upper rim and polyoxyethylene groups at the lower rim (9CO9) are developed for the destruction of toxic phosphorus acid esters. In the microheterogeneous 9CO9–polyethyleneimine (PEI)–lanthanum salt systems, a step-by-step enhancement of the catalytic activity was accomplished and a ca. 200-fold acceleration of hydrolysis is reached. The effect is contributed by the superposition of the factors of micellar catalysis (the concentration of reagents and changes in their microenvironment) and homogeneous catalytic mechanisms, in particular the general basic catalysis by aminogroups of PEI and the electrophilic catalysis by the La(III) ions. A further increase in the catalytic performance is achieved through the covalent immobilization of 9CO9 on the mesoporous silica. An inhibition/catalysis inversion occurs upon transferring from the single 9CO9 solution to the supported 9CO9@SiO2 particles.
Lucia Zakharova, Yuliana Kudryashova, Alsu Ibragimova, Elmira Vasilieva, Farida Valeeva, Elena Popova, Svetlana Solovieva, Igor Antipin, Yulia Ganeeva, Tatiana Yusupova, Alexander Konovalov, Chemical Engineering Journal 185– 186 (2012) 285– 293

B3214 – Octane number enhancement studies of naphtha over noble metal loaded zeolite catalysts

An Indian industrial naphtha containing mixture of various hydrocarbons belong to n-paraffins, isoparaffins, naphthenes and aromatics falling in C5 to C9 carbon range has been studied for its octane boosting through the production of isoparaffins over various Pt loaded zeolite catalysts possessing different acidity and porosity properties. Optimum balance of acid and metal functionalities in 0.6 wt.% Pt loaded on BEA zeolite helped in achieving highest increase in research octane number (RON) from 44 to 80, suitable for gasoline applications, through the production of lower isoparaffins (iC4-iC6) along with C7+ isoparaffins.
Nagabhatla Viswanadham, Sandeep K. Saxena, M.O. Garg, Journal of Industrial and Engineering Chemistry 19 (2013) 950–955

B3213 – Effect of aluminium incorporation by the ‘‘pH-adjusting’’ method on the structural, acidic and catalytic properties of mesoporous SBA-15

A series of Al-SBA-15 catalysts in a wide compositional range (Si/Al = 130-5.2) was prepared by “pH-adjusting” aiming to evaluate the effect of aluminium incorporation on their structural, acidic and catalytic properties. The calcined materials were characterized by ICP, XRD, N2 adsorption/desorption, TEM, 27Al MAS NMR, microcalorimetry of ammonia adsorption and FTIR of adsorbed pyridine. It was found that the progressive incorporation of aluminium in SBA-15 has a positive effect on the structural and textural characteristics of catalysts as well as on the number of Brönsted and Lewis acid sites, whereas no net effect was observed on the relative distribution of acid sites according to their nature or strength. The catalytic properties of mesoporous SBA-15 aluminosilicates were finally evaluated by test-reactions in the liquid phase tert-butylation of phenol and isomerization of styrene oxide, under mild conditions. The catalytic results showed that the progressive incorporation of aluminium results in higher reaction rates in the O- and C-alkylation of phenol as well as isomerization of styrene oxide, providing evidence that the number of acid sites controls the catalytic activity of Al-SBA-15. On the other hand, the incorporation of aluminium had no effect on the selectivity to the reaction products, indicating that selectivity levels are controlled by the relative distribution of acid sites. It was also reported that Al-SBA-15 prepared by “pH-adjusting” are highly active catalysts in the isomerization of styrene oxide and very selective to phenylacetaldehyde.
A. Ungureanu, B. Dragoi, V. Hulea, T. Cacciaguerra, D. Meloni, V. Solinas, E. Dumitriu, Microporous and Mesoporous Materials 163 (2012) 51–64

B3210 – Novel high-temperature, high-vacuum, all-metal sample cells for microcalorimetric measurements of solids

The design of a novel microcalorimetric sample cell which allows rapid transfer of heat from the sample to the cell wall is described. The solid sample is dispersed around the internal walls of the cell. Since the thermopiles of the microcalorimeter are in contact with the outer surface of the cell, the new design of the cell allows rapid recording of the heat generated by the sample. The robust all-metal cell allows in situ sample activation under conditions of high vacuum and at temperatures up to 500?°C. The dispersion of the sample avoids any “deep bed” effects where gas may not be able to diffuse freely to the surface of all of the sample, which may be the case when a thick layer or plug of the sample is used. The cell enables faster acquisition of heat data and minimizes effects of self-heating of the sample. A simple tool, which assists the introduction of the solid sample into the cell and a compact resistor-element, which fits inside the cell for calibration, are described
Eric N. Coker, Hellmut G. Karge, Rev. Sci. Instrum. 68 „12…, December 1997

B3201 – Preparation of highly loaded and dispersed Ni/SiO2 catalysts

A highly loaded and dispersed Ni/SiO2–B catalyst was prepared by the precipitation method with an n-butanol drying process. Drying with n-butanol significantly increased the surface area of the catalyst as well as the reducibility and dispersion of supported nickel, leading to the high active nickel surface area (66 m2/g-catalyst). In addition, the surface acidity of the Ni/SiO2-B catalyst was significantly enhanced, as probed by the microcalorimetric adsorption of ammonia. Accordingly, this catalyst adsorbed great amount of toluene with the high initial heat of about 140 kJ/mol, and exhibited high activity for the hydrogenation of toluene to methyl cyclohexane.
Mingwei Xue, Shenghua Hu, Hui Chen, Yuchuan Fu, Jianyi Shen, Catalysis Communications 12 (2011) 332–336

B3197 – CO-free hydrogen production over Au/CeO2–Fe2O3 catalysts: Part 1. Impact of the support composition on the performance for the preferential CO oxidation reaction

Ce–Fe mixed oxides were prepared by urea gelation coprecipitation method and used as supports of gold catalysts. The impact of the support composition on the catalytic performance for the preferential CO oxidation (PROX) was studied by varying the Ce/(Ce + Fe) ratio. A deep characterization study by different tools such as XRD, HRTEM, TPR and FTIR spectroscopy was undertaken in order to correlate the structural characteristics of the catalysts and the gold oxidation state and dispersion with the catalytic properties. The results revealed that the variation of the support composition led to significant differences in the gold particles size (in the range 1–25 nm), which affected strongly the CO oxidation activity of Au/CeO2–Fe2O3 catalysts under PROX conditions. The following activity order was observed: Au/CeO2 ? Au/Ce50Fe50 > Au/Ce75Fe25 > Au/Ce25Fe75 > Au/Fe2O3. The support with composition 50 wt.% CeO2–50 wt.% Fe2O3 appeared beneficial not only for nucleation and growth of highly dispersed gold particles (1–1.8 nm), but also for activation of oxygen and its mobility. Moreover, the presence of Fe2O3 in the supports composition improved the resistance towards deactivation by CO2. The CeO2–Fe2O3 supports comprised different amount of two phases: cubic CeO2-like solid solution and hematite. The analysis of the characterization data suggested that the solid solution formation probably proceeded via a dopant interstitial compensation mechanism.
T. Tabakova, G. Avgouropoulos, J. Papavasiliou, M. Manzoli, F. Boccuzzi, K. Tenchev, F. Vindigni, T. Ioannides, Applied Catalysis B: Environmental 101 (2011) 256–265

B3139 – Partial oxidation of methane on Pt-supported lanthanide doped ceria–zirconia oxides: Effect of the surface/lattice oxygen mobility on catalytic performance

Partial oxidation of methane into syngas at short contact times (5–15 ms) was studied in both steady-state and transient modes at temperatures up to 850 °C in realistic feeds (CH4 content up to 20%, CH4/O2 = 2) with a minimum impact of mass and heat transfer for structured catalysts carrying Pt/Ln0.3Ce0.35Zr0.35O2?y (Ln = La, Pr, Gd) as thin layers on walls of corundum channel substrates. Oxygen mobility and reactivity of the active phase were characterized by oxygen isotope heteroexchange, temperature-programmed O2 desorption and CH4 reduction, isothermal pulse reduction by methane with wide variation of CH4 concentrations and TAP pulse studies. Experimental data point towards a selective oxidation of methane into syngas via a direct route with oxygen-assisted methane activation. This mechanistic feature is related to the strong Pt-support interaction stabilizing highly dispersed oxidic Pt species less active in CH4 and syngas combustion than metallic Pt clusters. Support activates O2 molecules and supplies active oxygen species to Pt sites. A high rate of oxygen diffusion on the surface and in the bulk of the support and Pt-support oxygen spillover stabilizes Pt in a well dispersed partially oxidized state while preventing coking at high concentrations of CH4 in the feed.
Vladislav A. Sadykov, Nathalia N. Sazonova, Aleksei S. Bobin, Vitalii S. Muzykantov, Elena L. Gubanova, Galina M. Alikina, Anton I. Lukashevich, Vladimir A. Rogov, Eugenia N. Ermakova, Ekaterina M. Sadovskaya, Nathalia V. Mezentseva, Ekaterina G. Zevak, Sergei A. Veniaminov, Martin Muhler, Claude Mirodatos, Yves Schuurman, Andre C. van Veen, Catalysis Today 169 (2011) 125–137

B3138 – Structure and surface chemistry in crystalline mesoporous (CeO2-?)–YSZ

Mesoporous metal oxides (CeO2-?)-YSZ have been synthesized by a versatile direct synthesis method using ionic cetyltrimethylammonium bromide (CTAB) and different nonionic (block copolymers) as surfactants and urea as hydrolyzing agent. The synthesis was realized at pH = 9 using tetraethylammonium hydroxide (TEAOH) as pH mediator. Calcination at 550 °C led to the formation of crystalline metal oxides with uniform mesoporosity. The obtained materials have been characterized by thermogravimetric analysis (TG-DTG), wide and small-angle X-ray diffraction (XRD), Raman spectroscopy, Brunauer, Emmett and Teller (BET) surface area analysis, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). All the obtained materials exhibits mesoporous structure, crystalline structure indexed in a cubic symmetry, showing a high surface area, a uniform and narrow pore size distribution, spherical morphology typical for the mesoporous materials. The crystalline and mesoporous structures, surface chemistry and stoichiometry for the samples synthesized using ionic and nonionic surfactants have been discussed.
Simona Somacescu, Viorica Parvulescu, Petre Osiceanu, Jose Maria Calderon-Moreno, Bao-Lian Su, Journal of Colloid and Interface Science 363 (2011) 165–174

B3137 – Co-feeding water to attenuate deactivation of the catalyst metallic function (CuO–ZnO–Al2O3) by coke in the direct synthesis of dimethyl ether

Co-feeding water with syngas in the direct synthesis of dimethyl ether has been studied in order to reduce the deactivation by coke deposition on the CuO–ZnO–Al2O3 metallic function in the CuO–ZnO–Al2O3/?-Al2O3 bifunctional catalyst. The runs (synthesis of methanol and synthesis of DME) have been carried out in an isothermal fixed bed reactor under conditions avoiding catalyst deactivation due to the sintering of the metallic function (<325 °C) and the deactivation of the acid function (with an excess of ?-Al2O3 in the catalyst). The results of long-term experiments evidence that water in the reaction medium attenuates coke deposition during the methanol synthesis step, which is the limiting one. Water is understood to partially inhibit the formation of coke precursor methoxy ions. Furthermore, the formation of paraffins is attenuated by co-feeding water.
Irene Sierra, Javier Erena, Andrés T. Aguayo, José M. Arandes, Martin Olazar, Javier Bilbao, Applied Catalysis B: Environmental 106 (2011) 167– 173

B3131 – Synthesis, characterization and catalytic performance of titania supported VPO catalysts for the ammoxidation of 3-picoline

Series of vanadium phosphorus oxide (VPO) catalysts supported over titania (anatase) were synthesised with varying contents of VPO (5–50 wt%). These solids were characterised by ICP-OES, TG/DTA, BET, XRD, FTIR (Py-ads) and XPS. The catalytic activity was evaluated for ammoxidation of 3-picoline (3-pic) to nicotinonitrile (NN) in a fixed bed catalytic reactor. Thermal analysis provided good hints on the phase transformation of VHP precursor into active VPP phase at around 400 °C. BET surface areas and pore volumes are found to depend on VPO loading and varied in the range from 70 m2/g to 133 m2/g. XRD demonstrates the formation of (VO)2P2O7 (VPP) phase. XPS showed that an average oxidation state of vanadium around 4.0, which is found to be unaltered in the spent samples. FTIR (Py-ads) revealed the presence of both Lewis and Brønsted sites with varying proportions, which again depend upon VPO loading. Correlation of acidic properties (Lewis and Brønsted acid sites) of the catalysts with that of performance of catalysts was explored. VPO loading has a clear influence on the acidic properties and thereby catalytic activity and selectivity. Catalytic results showed that the supported catalysts gave better performance compared to bulk VPO. Yield of NN increased up to 20 wt% VPO loading and then decreased with further increase in VPO content. Among all catalysts tested, the 20 wt% VPO/TiO2 exhibited the best performance (X-3-pic = ca. 100% and Y-NN = 83%).
V.N. Kalevaru, N. Madaan, A. Martin, Applied Catalysis A: General 391 (2011) 52–62

B3127 – Consequences of the iron–aluminium exchange on the performance of hydrotalcite-derived mixed oxides for ethanol condensation

The effect of the partial and total substitution of aluminium by iron on the performance of different hydrotalcite-derived mixed oxides for the condensation of ethanol for obtaining valuable C4 products (mainly butanol and 1,3,-butadiene) has been studied in this work. Ethanol condensation reactions have been performed in a fixed bed reactor at 0.1 MPa, WHSV = 0.215 h?1 and 473–723 K. Three different hydrotalcite-derived mixed oxide with an atomic Mg2+/M3+ ratio of 3 (namely Mg6Al2O9, Mg6AlFeO9 and Mg6Fe2O9) have been prepared by a previously optimized procedure, tested as catalyst for the above mentioned reaction and characterized by TG–DTG, NH3-TPD, CO2 adsorption (calorimetric, TG–DTG and FTIR), Mossbauer Spectroscopy and TPR. The substitution of Al3+ by Fe3+ in the structure of the resulting mixed oxide leads to a slight decrease of the basic sites and a more marked decrease of the concentration of acid sites, being the concentration of these last sites negligible when the Al3+ cation is completely replaced by Fe3+. Accordingly, Mg–Fe mixed oxide is the most selective catalyst for the formation of C4 compounds, especially butanol. The almost total abatement of the acid sites of this material largely decrease the selectivity for ethanol dehydration, resulting in an increase of the formation of the dehydrogenation product (acetaldehyde), key reactant for condensation reactions.
Marta León, Eva Díaz, Aurelio Vega, Salvador Ordónez, Aline Auroux, Applied Catalysis B: Environmental 102 (2011) 590–599

B3126 – A kinetic study of CO2 desorption from basic materials: Correlation with adsorption properties

The kinetics of the CO2 desorption from basic materials has been studied in this work. For this purpose, temperature-programmed desorption of CO2 from different basic materials (hydrotalcite-derived alkaline mixed oxides and enhanced magnesium oxides) has been determined by thermogravimetry, and mathematically analysed by two different approaches: Kissinger and isoconversional methods. We present in this work a modification of the Kissinger Method for taking into account complex desorption profiles. According to this modification, TPD profile is deconvoluted into the sum of Gaussian peaks, Kissinger methodology being applied to these peaks. Both approaches provide kinetic parameters with physical sense, which explains the different behaviour of these adsorbents in terms of the interaction of the CO2 molecule with the active sites of the adsorbents. Obtained values of activation energy (75–90 kJ/mol for the weak sites and 100–160 kJ/mol for the strong sites) and pre-exponential factors (107–1012 min?1) were checked for physicochemical consistence (considering both the order of magnitude and the consistence with adsorption enthalpies), and were correlated with adsorption properties measured by microcalorimetry.
Marta León, Eva Díaz, Aurelio Vega, Salvador Ordónez, Chemical Engineering Journal 175 (2011) 341– 348

B3123 – Role of pore structure in the deactivation of zeolites (HZSM-5, H? and HY) by coke in the pyrolysis of polyethylene in a conical spouted bed reactor

The deactivation of three different catalysts used in the cracking of high density polyethylene (HDPE) has been compared. The catalysts used are HZSM-5, H? and HY zeolites agglomerated with bentonite and alumina. The reactions have been carried out in a conical spouted bed reactor at 500 °C, and plastic (high density polyethylene) has been fed in continuous mode (1 g min?1) for up to 15 h of reaction. The HZSM-5 zeolite catalyst gives way to high yields ofC2-C4olefins (57 wt%) and, moreover, it is the one least influenced by deactivation throughout the run, which is explained by the lower deterioration of its physical properties and acidity. The results of temperature program combustion and transmission electron microscopy show that coke growth is hindered in the HZSM-5 zeolite pore structure. The high N2 flow rate used in the conical spouted bed reactor enhances coke precursor circulation towards the outside of the zeolite crystal channels.
G. Elordi, M. Olazar, G. Lopez, P. Castano, J. Bilbao, Applied Catalysis B: Environmental 102 (2011) 224–231

B3121 – Insights into the coke deposited on HZSM-5, H? and HY zeolites during the cracking of polyethylene

The effect of the zeolite structure (HZSM-5, H? and HY) on coke deposition during the cracking of high-density polyethylene has been studied by combining the results of multiple spectroscopic and analytical techniques: FTIR, Raman, UV-vis, 13C NMR and coke extraction, followed by GC-MS and 1H NMR analysis. In addition, by combining FTIR and temperature programmed oxidation (TPO) analysis we obtained information on the coke: properties, burn-off, and changes in composition during catalyst regeneration. Samples of the spent catalysts were obtained in a state-of-the-art pilot plant (conical spouted bed reactor) after the continuous treatment of 900g (1g min?1, 15 h) of high-density polyethylene at 500 C, using 30 g of catalyst. The results show that as the pore diameter of the zeolite is increased, bimolecular reactions (hydrogen transfer and oligomerizations), condensations and cyclizations are enhanced, yielding more aromatic coke. Furthermore, the pore topology of the HZSM-5 zeolite improves the flow of coke precursors (also favored by the high flow rate of N2) to the outside of the catalyst; viz. HZSM-5 catalyst preserves its activity for longer.
Pedro Castano, Gorka Elordi, Martin Olazar, Andres T. Aguayo, Bárbara Pawelec, Javier Bilbao, Applied Catalysis B: Environmental 104 (2011) 91–100

B3111 – Palladium catalysts supported on N-functionalized hollow vapor-grown carbon nanofibers: The effect of the basic support and catalyst reduction temperature

The basic N-functionalized vapor-grown carbon nanofibers (N-VGCF) were synthesized by post-treating oxidized VGCFs in gaseous NH3 at high temperature (ammonolysis) prior to Pd addition by sol immobilization. The catalysts were characterized by nitrogen adsorption, hydrogen temperature programmed desorption, adsorption microcalorimetry and by SEM and TEM. Catalytic activity was evaluated in a model reaction, synthesis of (R)-1-phenylethyl acetate starting from hydrogenation of acetophenone to racemic 1-phenylethanol over Pd supported on N-VGCFs, at 70 °C under atmospheric hydrogen pressure in toluene, followed by acylation over an immobilized lipase in the same reaction pot. The main parameters investigated in this work were the role of the basic N-VGCF supports as well as the reduction procedure of the supported Pd catalysts (Pd-N-VGCF). The results revealed that the catalytic activity of the Pd-N-VGCF catalysts was highly dependent on the reduction procedure. The highest desired product yield, 35%, was obtained over a Pd-N-VGCF catalyst when the support was treated at 400 °C with gaseous ammonia prior to Pd addition.
Serap Sahin, Päivi Mäki-Arvela, Jean-Philippe Tessonnier, Alberto Villa, Sylvia Reiche, Sabine Wrabetz, Dangsheng Su, Robert Schlögl, Tapio Salmi, Dmitry Yu. Murzin, Applied Catalysis A: General 408 (2011) 137– 147

B3110 – Cellulose hydrothermal conversion promoted by heterogeneous Brønsted and Lewis acids: Remarkable efficiency of solid Lewis acids to produce lactic acid

Crystalline cellulose treated in hydrothermal conditions (190 °C, 24 h) is partially solubilised, 30%, into water soluble oligosaccharides/polymers with the formation of small amounts of glucose and 5-HMF. In the presence of solid Brønsted catalysts such as Cs2HPW12O40 and HY zeolite, the extent of the cellulose depolymerisation was not changed when no leaching occurred. However, a quite different products distribution was obtained, in favour of further transformations of glucose and HMF in levulinic and formic acids. On the opposite, solid Lewis acids such as tungstated zirconia (ZrW) and tungstated alumina (AlW) exhibited a remarkable promoting effect on the cellulose depolymerisation which was raised up to 45% while an unexpected decrease of the proportion of water soluble oligosaccharides/polymers was observed. Yields of 27 mol% and 18.5 mol% in lactic acid were achieved on AlW and ZrW, respectively. Moreover, these tungsten based Lewis acids exhibited a good stability and recyclability. The efficiency of the solid Lewis acids ZrW and AlW to produce lactic acid directly from crystalline cellulose was explained by a positive synergy between water autoprotolysis responsible of the cellulose depolymerisation into soluble intermediates which are further converted on the solid Lewis catalyst surface.
Flora Chambon, Franck Rataboul, Catherine Pinel, Amandine Cabiac, Emmanuelle Guillon, Nadine Essayem, Applied Catalysis B: Environmental 105 (2011) 171–181

B3109 – Co-production of butyrate methyl ester and triacetylglycerol from tributyrin and methyl acetate

The simultaneous synthesis of butyric acid methyl ester, the shortest component of the FAME (fatty acid methyl esters) family, and glycerol triacetate (TAG) from glycerol tributyrate (tributyrin) and methyl acetate was studied as a function of several reaction parameters, such as type of catalyst, temperature and products distribution. The reaction is an interesterification, a multistep consecutive ester interchange catalyzed by either acid or base catalyst. Under optimized conditions, a complete tributyrin conversion and an almost quantitative butyric acid methyl ester accumulation were achieved. The other reaction product, TAG, formed by the complete acetylation of the glycerol moiety, reached almost 70% yield, whereas the mono- and di-acetylated intermediates accumulated in the order of 5–8% and 24–27%, respectively. Similar final conversions and products yields were obtained with either acid or base homogeneous catalysts, suggesting that the final products mixture did not depend on the type of catalysis but might be limited by equilibrium conditions. In spite of similar final yields, base catalysis needed shorter reaction times (minutes instead of hours) and lower temperature (60 °C instead of 130 °C) with respect to the best acid catalyst. On the other hand, unlike heterogeneous basic catalysts, which showed low activity, a heterogeneous acid catalyst almost as active as the homogenous counterpart was found.
Ezio Battistel, Chiara Calaprice, Enrico Gualdi, Elena Rebesco, Elisabetta Maria Usai, Applied Catalysis A: General 394 (2011) 149–157

B3089 – Catalytic steam reforming of methane under conditions of applicability with Pd membranes over supported Ru catalysts

Three Ru catalysts supported on SiO2, ZrO2–SiO2 and ZrO2–La2O3 have been prepared, characterized and tested in the methane steam reforming (SR) reaction, and for comparative purposes a Ni/SiO2 catalyst has also been studied. Conditions of catalytic studies have been selected for the subsequent application in a hydrogen extraction Pd membrane reactor. That is, reaction temperatures in the range of 400–550 °C and with different amounts of catalyst in order to work under and/or close to the equilibrium conversion conditions. All the supported Ru samples exhibit high catalytic activity and similar CO and H2 yields. Finally these catalysts are fully stable under reaction conditions at 550 °C for 15 h, while the Ni/SiO2 sample suffers a significant deactivation. The main deactivation process affecting this latter catalyst is the carbon deposition of partially dehydrogenated intermediates as detected by Raman spectroscopy. Hence, these Ru catalysts appear to be suitable for application combined with metallic (Pd) membrane.
M.A. Soria, C. Mateos-Pedrero, I. Rodríguez-Ramos, A. Guerrero-Ruiz, Catalysis Today 171 (2011) 126– 131

B3088 – The poisoning level of Pt/C catalysts used in PEM fuel cells by the hydrogen feed gas impurities: The bonding strength

Proton exchange membrane fuel cells (PEMFCs) most likely will use reformed fuel as the primary source for the anode feed despite it nearly always contains carbon monoxide or ammonia. In this paper, the microcalorimetry technique was employed to study and compare the poisoning effect of pollutants such as CO and NH3 on three commercial carbon-supported platinum catalysts with high Pt loading, aimed to be used in PEMFCs applications. Microcalorimetric measurements were performed at 80 °C and the results were compared with those obtained from hydrogen adsorption in similar conditions. All the catalysts exhibited significantly higher differential heats of CO adsorption in comparison with NH3 and hydrogen adsorption, indicating that carbon monoxide will be primarily adsorbed in case of co-adsorption, while ammonia and hydrogen will compete in the adsorption process on the same type of active sites. The irreversibly (chemically) amount of adsorbed molecules on Pt/C surfaces decreases in the order: CO >> NH3 > H2.
Georgeta Postole, Aline Auroux, International Journal of Hydrogen Energy 36 (2011) 6817-6825

B3082 – Nitrogen-containing mesoporous carbons prepared from melamine formaldehyde resins with CaCl2 as a template

Melamine formaldehyde resins were synthesized with encapsulated CaCl(2) as a template. Carbonization at high temperatures led to the formation of carbon materials containing N atoms. Washing with de-ionized water removed encapsulated CaCl(2), resulting in the formation of mesopores (3-30 nm) with the high surface areas (770-1300 m(2)/g). The template can be recycled and the method is simple and cost effective as compared to the hard template techniques. The mesoporous carbons containing nitrogen (NMC) thus prepared exhibited the amphipathic surfaces (both hydrophilic and lipophilic) and adsorbed great amount of water and benzene. In addition, the incorporated N atoms exhibited quite strong basicity for the adsorption of great amount of SO(2).
Yuan Huang, Feng Yang, Zheng Xu, Jianyi Shen, Journal of Colloid and Interface Science 363 (2011) 193–198

B3080 – Microcalorimetric adsorption studies of highly loaded Co–ZrO2/SiO2 catalysts for Fischer–Tropsch synthesis

Highly loaded Co/SiO2 catalysts were prepared by a co-precipitation technique with an n-butanol drying process for Fischer–Tropsch synthesis (FTS). With the increase in cobalt loading from 20% to 80%, the FTS activity of the catalysts increased greatly. The addition of ZrO2 improved the dispersion of cobalt and promoted the adsorption of H2 and CO on cobalt. The preadsorbed H atoms significantly enhanced the adsorption of CO and C2H4, especially on cobalt promoted by ZrO2. While the adsorption of C2H4 onto clean cobalt led to the formation of ethylidyne, ?- and di-?-bonded C2H4 might form on the CO-preadsorbed 80%Co/SiO2 and 80%Co–8%ZrO2/SiO2, respectively. The presence of ZrO2 strengthened the bonding of molecularly adsorbed ethylene and increased its uptake on CO-preadsorbed cobalt, which might be why the 80%Co–8%ZrO2/SiO2 exhibited such high activity for the hydrogenation of CO to heavy hydrocarbons.
Liang Chen, Jianyi Shen, Journal of Catalysis 279 (2011) 246–256

B3043 – Surface properties of Ru particles supported on carbon materials: A microcalorimetric study of the effects over the CO chemisorptions of residual anionic species

Chemisorption of CO combined with microcalorimetry has been applied to study the nature, number and adsorption strength distribution of surface sites exposed by carbon-supported Ru catalysts. A comparative analysis of the CO chemisorption on different Ru catalysts, prepared using two different metal precursors, RuCl3·xH2O and Ru(NO)(NO3)3, has been carried out. An activated carbon and the corresponding derivative where oxygen surface groups were incorporated, as well as carbon nanotubes and a high surface area graphite, were used as catalytic supports. Based on previous temperature programmed reduction studies, all the catalysts were reduced under hydrogen flow at 523 K or at 573 K. The CO adsorption differential enthalpy profiles show that Ru(NO)(NO3)3 precursor produces more homogeneous surface site distribution in the Ru nanocrystals, in comparison with those prepared from RuCl3, as well as higher values of enthalpies in the medium range of coverage. As a possible explanation for this effect, residual chloride species remaining after reduction treatment in the ex-chloride catalysts, that can be anchored to the Ru nanoparticles weakening the CO adsorption, have been considered. This behavior occurs for the three studied carbon supports. On the other hand, the oxygen surface groups incorporated on the activated carbon seem not to modify the CO adsorption properties of the catalysts, independently of the precursor employed
A. Guerrero-Ruiz, E. Gallegos-Suárez, L. Gonzalo-Chacón, I. Rodríguez-Ramos, Thermochimica Acta (2012)

B3042 – Effect of the K+, Ba2+, and Nd3+ addition to Nb2O5 on intrinsic and effective acidity in relation to biomass reactions

The mitigation of surface acidity and tuning of acid strength of niobic acid were successfully obtained by K+, Ba2+, and Nd3+ surface doping. Three series of doped samples with different amounts of each metal ion on niobic acid (2–15 atoms nm?2, 1–10 atoms nm?2, and 1–6 atoms nm?2 for K, Ba, and Nd, respectively) were prepared and characterized by various surface and bulk techniques (N2-adsorption, TGA, SEM–EDS, and UV–vis-DRS). Particular attention was paid to the acidity determination that was performed with different techniques: by conventional NH3 adsorption in a volumetric–calorimetric apparatus, by temperature-programmed desorption of PEA (2-phenylethyl-amine), and by PEA titrations in water. The acidity results obtained in water have been used to determine the sample effective acidity. The results revealed that Ba and Nd dopants were more effective than K dopant in decreasing the effective acidity of niobic acid. On the three sample series, the reactions of fructose dehydration and sucrose hydrolysis have been taken into account as model reactions to control the nature (Brønsted or Lewis acid sites, BAS, or LAS) of the catalytic acid sites still active in water. Results indicated that K+ ion doped more selectively the BAS while Ba2+ and Nd3+ ions modified more the LAS population of niobic acid.
Antonella Gervasini, Paolo Carniti, Matteo Marzo, Aline Auroux, Journal of Catalysis 296 (2012) 143–155

B3031 – Oxidative steam reforming of ethanol over Ir/CeO2 catalysts: A structure sensitivity analysis

A series of Ir/CeO2 catalysts of different oxide and metallic phase dispersions was investigated by XRD, TPR, HRTEM, CO2 TPD/calorimetry, in situ DRIFT spectroscopy, and oxygen isotopic exchange techniques in order to elucidate the specific influence of catalyst morphology and structure on the oxidative steam reforming (OSR) of ethanol. Structure/texture sensitivity is demonstrated on the basis of the OSR mechanism, which involves, in order: (i) ethanol adsorption on the ceria surface, (ii) partial oxidation to acetate and surface migration of the C2 intermediates along the ceria support toward the Ir particles, (iii) cracking and further oxidation into Ir carbonyls and ceria carbonates, and (iv) hydrogen and carbon monoxide desorption from the Ir particles. Structure sensitivity is established by considering two types of sites: the ceria surface sites, which are essentially pairs of oxygen vacancies and basic OH groups, as well as interfacial sites between Ir and ceria phases, involving pairs of Ir coordinately unsaturated sites (CUSs) and the aforementioned peripheral ceria sites. This structure sensitivity is revealed by TOF calculations based on these two types of sites, which correspond to the two main rate controlling steps of the ethanol OSR mechanism, namely steps (ii) and (iii). The materials considered display activity, selectivity, and resistance to aging (manifested by coke deposition and sintering) that are closely related to their initial structure and texture. Two domains in terms of iridium and ceria particle size are identified, leading either to stable and selective catalysts or to unstable and unselective catalysts. Such an original and quantified structure sensitivity analysis should prove useful for further process development.
Weijie Cai, Fagen Wang, Cécile Daniel, Andre C. van Veen, Yves Schuurman, Claude Descorme, Hélène Provendier, Wenjie Shen, Claude Mirodatos, Journal of Catalysis 286 (2012) 137–152

B3029 – Microwave calcination of Cu/Mg/Al hydrotalcite catalyst precursor

A copper-substituted hydrotalcite (Cu1.4Mg4.4Al2.2(CO3)1.1(OH)16) has been subjected to calcination under feedback-controlled microwave heating, in which microwave power is continuously modulated to generate a defined sample temperature programme or constant sample temperature. The results show that microwave calcination results in enhanced crystallinity of the resultant oxides and spinel phase formed at high temperature, compared to conventional calcination. In addition, an additional phase, Cu2MgO3, is detected following microwave calcination, at a bulk temperature very much lower than previously reported for copper-containing hydrotalcite. The concentrations and strengths of surface basic sites are significantly higher for materials calcined using microwaves than using conventional heating. Catalytic activities in the base-catalysed transesterification of glyceryl tributyrate with methanol are also higher. We suggest that microwave calcination under feedback-control, while allowing control of material bulk temperature during calcination and preventing major temperature excursions, may allow quite large but highly localised temperature variation, for instance as water is released during dehydroxylation, which are beneficial in developing surface defects and surface basicity.
H.E. Cross, G. Parkes, D.R. Brown, Applied Catalysis A: General 429– 430 (2012) 24– 30

B3017 – The effect of surface acidic and basic properties on the hydrogenation of lauronitrile over the supported nickel catalysts

Supported nickel catalysts with different supports (MgO, SiO2, Al2O3, MgAlO and SiAlO) were prepared by the co-precipitation method and dried in n-butanol. Nickel was found to be relatively easier to reduce in Ni/MgO and Ni/SiO2 than in Ni/Al2O3, while nickel was higher dispersed in Ni/SiO2 than in Ni/Al2O3 and Ni/MgO. Thus, the reducibility and dispersion of nickel in Ni/MgAlO and Ni/SiAlO were significantly enhanced, leading to the high active nickel surface areas (75 m2/g-catalyst). Acetonitrile was found to be adsorbed on the reduced nickel and acidic sites. The strong surface basicity of Ni/MgO was found to favor the selectivity to the primary amine, but inhibited the conversion of lauronitrile. On the other hand, the conversion of lauronitrile was high over the Ni/SiO2, Ni/Al2O3 and Ni/SiAlO with strong surface acidity, but the selectivity to the prime amine was relatively low. The Ni/MgAlO with intermediate strengths of surface acidity and basicity exhibited the high conversion of lauronitrile and high selectivity to the prime amine.
Hui Chen, Mingwei Xue, Shenghua Hu, Jianyi Shen, Chemical Engineering Journal 181– 182 (2012) 677– 684

B3016 – The effects of promoters of K and Zr on the mesoporous carbon supported cobalt catalysts for Fischer–Tropsch synthesis

The mesoporous carbon supported cobalt catalyst (15%Co/MC) was found to be more active and selective to C+5 than the traditionally activated carbon supported one (15%Co/AC) for the Fischer–Tropsch synthesis (FTS). The addition of small amount of K2O and ZrO2 significantly affected the FTS behavior of 15%Co/MC. The addition of 1% K inhibited the FTS activity dramatically, while the addition of 3% Zr increased the FTS activity significantly. The addition of K2O decreased the surface acidity while increased the surface basicity of 15%Co/MC, resulting in the increased heat of adsorption of CO and substantially decreased heat of adsorption of H2 on Co. In contrast, the addition of ZrO2 increased the surface acidity and heat of adsorption of H2 on Co. The FTS activity was found to be related to the ratio of heats for the adsorption of CO and H2 on the catalysts 15%Co/MC, 15%Co–1%K/MC and 15%Co–3%Zr/MC. The highest FTS activity was obtained on the catalyst with the heat ratio of 1.2.
Liang Chen, Guoxia Song, Yuchuan Fu, Jianyi Shen, Journal of Colloid and Interface Science 368 (2012) 456–461

B3015 – Influence of the nature of support on Ru-supported catalysts for selective hydrogenation of citral

Ruthenium catalysts supported on KL zeolite, ZrO2 and graphite, prepared by incipient wetness impregnation, were characterized by N2 adsorption, H2 chemisorption, TEM and CO adsorption microcalorimetry and tested in the selective hydrogenation of citral in the liquid phase, at 5 MPa and 323 K. Characterization studies reveal that graphite promotes formation of electron-rich metal species (Run ) that difficult hydrogenation of the conjugated C@C double bond of citral and indirectly favor the production of geraniol and nerol. For Ru/ZrO2 catalyst, the RuMZrO2 interaction at the interface, with formation of Ru0AZrn+ species as evidenced by the TEM and CO adsorption microcalorimetry measurements, activates the carbonyl group of citral and enhances the selectivity towards unsaturated alcohols. Characterization measurements of Ru/KL evidence that metal nanoparticles placed inside of the zeolite channels block part of ruthenium loading and hinder the free transit of citral through the channels, thus reducing the overall hydrogenation activity of the catalyst. Furthermore, this steric hindrance impedes adsorption the conjugated C@C double bond of citral and forces hydrogenation of the carbonyl group in terminal position. On the other hand, the fact that active sites on occluded particles are more resistant to poisoning than those easily accessible to citral enhances the selectivity towards geraniol and nerol, as the reaction time increases. The comparative analysis of the results indicates that, in order to increase the selectivity towards unsaturated alcohols, geometrical effects derived from the size, shape and location of ruthenium particles in the KL structure are more effective than the electronic modifications induced by graphite or zirconia on the ruthenium particles.
J. Álvarez-Rodríguez, I. Rodríguez-Ramos, A. Guerrero-Ruiz, E. Gallegos-Suarez, A. Arcoya, Chemical Engineering Journal 204–206 (2012) 169–178

B3014 – Activated carbons from KOH-activation of argan (Argania spinosa) seed shells as supercapacitor electrodes

Activated carbons were prepared by KOH-activation of argan seed shells (ASS). The activated carbon with the largest surface area and most developed porosity was superficially treated to introduce oxygen and nitrogen functionalities. Activated carbons with a surface area of around 2100 m2/g were obtained. Electrochemical measurements were carried out with a three-electrode cell using 1 M H2SO4 as electrolyte and Ag/AgCl as reference electrode. The O-rich activated carbon showed the lowest capacitance (259 F/g at 125 mA/g) and the lowest capacity retention (52% at 1 A/g), due to surface carboxyl groups hindering electrolyte diffusion into the pores. Conversely, the N-rich activated carbon showed the highest capacitance (355 F/g at 125 mA/g) with the highest retention (93% at 1 A/g), due to its well-developed micromesoporosity and the pseudocapacitance effects of N functionalities. This capacitance performance was among the highest reported for other activated carbons from a large variety of biomass precursors
Abdelhakim Elmouwahidi, Zulamita Zapata-Benabithe, Francisco Carrasco-Marín, Carlos Moreno-Castilla, Bioresource Technology 111 (2012) 185–190

B3005 – Adsorption and differential heats of adsorption of normal and iso-butane on zeolite MFI

Adsorption of n- and i-butane on zeolite MFI (silicalite type) at different temperatures has been investigated using a manometric technique combined with a micro-calorimeter. The Langmuir model can describe the isotherms for both components. The derived thermodynamic properties are in agreement with the literature data from other techniques. The differential heats of adsorption when plotted against loading present an initial plateau; followed by a slow rise, which can be attributed to adsorbate–adsorbate interactions. For i-butane these adsorbate–adsorbate interactions give rise to a sharp peak in heat of adsorption versus loading, at 0.6 mmol/g. A decrease at higher loadings on the heat of adsorption is observed for both isomers, this is attributed to surface adsorption
Alexandre F.P. Ferreira, Marjo C. Mittelmeijer-Hazeleger, Alfred Bliek, Microporous and Mesoporous Materials 91 (2006) 47–52

B3004 – Specific and non-specific interactions on non-porous carbon black surfaces

The interactions which occur between methanol, ethanol or propanol and the surfaces of non-porous carbon blacks with increasing levels of oxygen chemistry have been studied using adsorption isotherm analysis and immersion calorimetry. Surface oxygen has been controlled by ozone treatment and characterised using X-ray photoelectron spectroscopy, which gives a direct and quantitative measure of surface composition from first-principles, and has not yet been extensively employed in detailed carbon adsorption studies. Nitrogen adsorption at 77 K and heat of immersion hi (mJ m-2) data for toluene, show that the physical structure of the carbon blacks is not modified by ozone treatment. A systematic shift to higher adsorption values, due to increasing specific hydrogen bonding interactions between the alcohol –OH groups and surface oxygen, is observed in all of the alcohol isotherms as the total oxygen content of the carbon surfaces ([O]T/at.%) increases. This effect is most significant for methanol confirming that the mechanism of adsorption is dominated by hydrogen bonding and therefore dependant on the surface concentration of oxygen sites. It is also observed for ethanol and propanol but is less marked due to the increasing non-specific, dispersion, interactions of the alkyl chain with the non-polar carbon surface. This description is in agreement with the data obtained for the specific enthalpies of immersion hi (mJ m-2) into the alcohols and into water or toluene which allow a semi-quantitative assessment off the relative polar and dispersion contributions to the overall interactions as functions of both carbon surface oxygen composition and the molecular structure of the alcohols. An overall correlation is observed between adsorption behaviour, [O]T/at.%, the resulting hi values and the characteristic energy E (kJ mol 1) of the DRK equation. It is also observed that the values of the affinity coefficient bDRK increase directly as a function of [O]T indicating that this latter parameter may provide a basis for predicting the adsorption isotherms of certain polar vapours on non-porous carbon surfaces. The effects of carbon surface chemistry on the character of adsorption isotherms, which change from Type III for the base N330 (and for a graphitized carbon black N234G) to Type II for the oxidised N330 materials, is discussed and the resulting effects on the surface area parameters SDRK and SBET (m2 g-1) are considered.
A. Andreu, H.F. Stoeckli, R.H. Bradley, Carbon 45 (2007) 1854–1864

B3003 – Cluster-mediated filling of water vapor in intratube and interstitial nanospaces of single-wall carbon nanohorns

This study reports experimental data of water adsorption at 303 K on single-wall carbon nanohorns (SWNHs). The analysis of the water adsorption isotherms supports a cluster-mediated model for filling the interstitial and intratube nanospaces in contrast to the monolayer formation observed for simple nonpolar molecules. The enthalpies of water immersion of SWNHs with closed and open nanohorns show a very week interaction between the water molecules and the hydrophobic carbon nanotubular structure; the observed specific enthalpy of immersion expressed per unit surface area is lower than the reported values for graphite.
E. Bekyarova, Y. Hanzawa, K. Kaneko, J. Silvestre-Albero, A. Sepulveda-Escribano, F. Rodriguez-Reinoso, D. Kasuya, M. Yudasaka, S. Iijima, Chemical Physics Letters 366 (2002) 463–468

B3001 – Structural and surface modifications of carbon nanotubes when submitted to high temperature annealing treatments

Multiwall carbon nanotubes (MWCNTs) were synthesized using a chemical vapour deposition procedure using acetylene as source of carbon, iron pentacarbonyl as catalyst and an inert carrier gas. An aliquot of these MWCNTs was heat-treated at 2873 K under inert atmosphere (Ar). The two carbon nanotube samples where characterized using high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy, nitrogen adsorption at 77 K, Raman spectroscopy, and immersion calorimetry in toluene, methanol and methylcyclohexane. HRTEM images confirmed that high-temperature treatment removed amorphous carbon, the graphene layers being better graphitized, and also some structural changes inside the cylindrical mesopores took place. Immersion enthalpies in toluene, in which molecules are present as aromatic functions, indicated the existence of specific – electronic interactions between such molecules and the surface of heat-treated MWCNTs.
E. Castillejos, B. Bachiller-Baeza, M. Pérez-Cadenas, E. Gallegos-Suarez, I. Rodríguez-Ramos, A. Guerrero-Ruiz, K. Tamargo-Martinez, A. Martinez-Alonso, J.M.D. Tascón, Journal of Alloys and Compounds 536S (2012) S460– S463

B3000 – An immersion calorimetric study of the interactions between some organic molecules and functionalized carbon nanotube surfaces

The interaction of organic chemicals with the surface of carbon nanotubes has been studied by immersion calorimetry revealing significant differences in the properties when these materials are modified thermally or chemically. Therefore, multiwall carbon nanotubes have been synthesized using a chemical vapour deposition procedure and subsequently aliquots were treated with HNO3 at reflux, maintaining the reaction during different times, in order to incorporate oxygen surface groups, or were treated at 2873 K under inert atmosphere. The aim of this thermal treatment is to eliminate structural defects of the carbon nanostructures and to graphitize the amorphous carbon phases. These features were confirmed by high-resolution transmission electron microscopy. The immersion in organic compounds, including toluene, methanol and methylcyclohexane, of all these carbon nanotubes samples reveals that the surface properties are remarkably modified. Thus, the formation of different types of interaction, depending on the surface, gives place to changes in the immersion enthalpies.
E. Castillejos-López, B. Bachiller-Baeza, A. Guerrero-Ruiz, I. Rodriguez-Ramos, Thermochimica Acta (2012)

B2999 – Effect of the carbon support nano-structures on the performance of Ru catalysts in the hydrogenation of paracetamol

Ru catalysts supported on three types of graphite nanofiber materials, stacked-cup (PR24-HHT), platelet (CNF-P) and bamboo-like (CNF-B), have been synthesized and characterized by HRTEM and calorimetry of CO adsorption. The influence of the support nanostructure on their catalytic performance in the selective hydrogenation of paracetamol was also studied. An inverse correlation between the heats of CO adsorption and the activity and stereoselectivity to the trans-4-acetamidocyclohexanol was found. The results have been rationalized in terms of the morphology and electronic properties of the metal particles. These features are controlled by the different location of the crystallites and the metal-support interactions induced that eventually depend on the nanostructure of the support. As a consequence the supports seem to modify the Ru nanoparticles surface structures, and the shift in selectivities can be related with variations of the reactant chemisorption over such Ru surfaces.
E. Asedegbega-Nieto, B. Bachiller-Baeza, D.G. Kuvshinov, F.R. Garc?a-Garc?a, E. Chukanov, G.G. Kuvshinov, A. Guerrero-Ruiz, I. Rodr?guez-Ramos, Carbon 46 (2008) 1046-1052

B2998 – Further insights into the Ru nanoparticles–carbon interactions and their role in the catalytic properties

Temperature-programmed reduction (TPR) and CO adsorption microcalorimetry along with the catalytic behaviour in the n-butane/H2 test reaction were performed in order to determine the specific interactions of Ru nanoparticles supported on different carbon materials. Aspects such as the porous structure and surface chemistry (presence and elimination of surface oxygen functional groups) of the carbon material, or the effect of the metal precursor (e.g. presence of residual chlorine) on the final metal dispersion and on the surface structure of the Ru nanoparticles have been studied. The results obtained confirmthat surface oxidation of the support along with the nature of the Ru precursor affects the distribution of the metal precursor over the support (and, consequently, the final ruthenium dispersion) and also the surface site distribution. Besides, elimination of the surface oxygen functional groups of the carbon material, during the reduction treatments of the fresh catalyst samples, leads to surface reconstructions on the Ru nanoparticles that seem to expose different crystallographic planes. The presence of residual chlorine leads to electron deficient Ru sites, and this modifies the CO chemisorption heats and affects the catalytic properties in the n-butane/hydrogen test.
M. Cerro-Alarcon, A. Maroto-Valiente, I. Rodr?guez-Ramos, A. Guerrero-Ruiz, Carbon 43 (2005) 2711–2722

B2997 – Carbon molecular sieve cloths prepared by chemical vapour deposition of methane for separation of gas mixtures

Microporous carbon molecular sieves for separating gaseous mixtures have been prepared through chemical vapour deposition (CVD) of methane on activated carbon cloth obtained from Nomex aramid fibre. The activated carbon fibres were subjected to CVD of methane for different periods of time. The textural characterization of the resulting materials was assessed by physical adsorption of gases (N2 and CO2) and vapours (dichloromethane, benzene and cyclohexane) as well as immersion calorimetry into the same liquids. A direct visualization of the changes induced by CVD on the micropore mouth structure of the activated carbon cloth was provided by scanning tunnelling microscopy (STM). The validity of the materials for separating CO2/CH4 and O2/N2 was tested by assessing the kinetics of adsorption of the corresponding gases. Carbon molecular sieves with good selectivity for CO2/CH4 separation and showing acceptable CO2 adsorption capacity were obtained.
S. Villar-Rodil, R. Navarrete, R. Denoyel, A. Albiniak, J.I. Paredes, A. Mart?nez-Alonso, J.M.D. Tascon, Microporous and Mesoporous Materials 77 (2005) 109–118

B2996 – Preparation, surface characteristics, and electrochemical double-layer capacitance of KOH-activated carbon aerogels and their O- and N-doped derivatives

Carbon aerogels are obtained by carbonizing organic aerogels prepared by polycondensation reaction of resorcinol or pyrocatechol with formaldehyde. They are KOH-activated at two KOH/carbon ratios to increase pore volume and surface area. Selected samples are also surface-treated to introduce oxygen and nitrogen functionalities. The objectives are to investigate the effect of porosity and surface functionalities on the electrochemical capacitance of the carbon and activated carbon aerogels. Samples are characterized by N2 and CO2 adsorption at 196 and 0°C, respectively, immersion calorimetry, temperature-programmed desorption, and X-ray photoelectron spectroscopy in order to determine their surface area, porosity, and surface chemistry. Two series of samples are obtained: one micro-mesoporous and the other basically microporous. A surface area up to 1935 m2 g-1 was obtained after KOH activation. Electrochemical double-layer capacitance was studied by cyclovoltammetry and chronopotentiometry with a three-electrode cell, using Ag/AgCl as reference electrode. Gravimetric capacitance at 0.125 A g-1 is related to N2 adsorption-measured micropore volume and mean size and to particle density. The highest gravimetric capacitance, 220 F g-1, is obtained with two O- and N-doped samples. Volumetric capacitance of 123 F cm-3, double the value generally needed for applications in small-volume systems, is obtained with a largely microporous oxygen-doped activated carbon aerogel.
Zulamita Zapata-Benabithe, Francisco Carrasco-Marín, Carlos Moreno-Castilla, Journal of Power Sources 219 (2012) 80-88

B2995 – Surface characteristics and electrochemical capacitances of carbon aerogels obtained from resorcinol and pyrocatechol using boric and oxalic acids as polymerization catalysts

Carbon aerogels were prepared by carbonizing (at 500–1500°C) organic aerogels obtained from the polymerization reaction of resorcinol and/or pyrocatechol with formaldehyde using boric and oxalic acids as polymerization catalysts. Prepared samples were characterized by different techniques to ascertain their composition, surface chemistry, morphology, and surface physics, determining their electrochemical capacitances in acidic medium. The use of pyrocatechol yielded carbon aerogels that were micro–mesoporous, showing Type IV N2 adsorption isotherms with Type H2 hysteresis cycles. The volume and size of mesopores depended on the acid catalyst used and the temperature at which the carbon aerogel was obtained. Conversely, the sample prepared with resorcinol and boric acid as catalyst was micro–macroporous and that obtained with a resorcinol–pyrocatechol mixture was micro–mesoporous but with large mesopores. Most of the boric acid used was lost during the exchange of water with acetone in the organic hydrogels before their supercritical CO2 drying. Carbon aerogels obtained at 900°C and using boric acid as polymerization catalyst showed a capacitance between 17 and 24 ?F/cm2. Boron influenced the capacitance because it increased the oxygen content. Sample synthesized using pyrocatechol, formaldehyde, and oxalic acid and heat-treated at 900°C had the highest capacitance, 34 ?lF/cm2.
Carlos Moreno-Castilla, Marta B. Dawidziuk, Francisco Carrasco-Marin, Zulamita Zapata-Benabithe, Carbon 49 (2011) 3808-3819

B2994 – Adsorption/bioadsorption of phthalic acid, an organic micropollutant present in landfill leachates, on activated carbons

This study investigated the adsorption of phthalic acid (PA) in aqueous phase on two activated carbons with different chemical natures, analyzing the influence of: solution pH, ionic strength, water matrix (ultrapure water, ground water, surface water, and wastewater), the presence of microorganisms in the medium, and the type of regime (static and dynamic). The activated carbons used had a high adsorption capacity (242.9 mg/g and 274.5 mg/g), which is enhanced with their phenolic groups content. The solution pH had a major effect on PA adsorption on activated carbon; this process is favored at acidic pHs. PA adsorption was not affected by the presence of electrolytes (ionic strength) in solution, but was enhanced by the presence of microorganisms (bacteria) due to their adsorption on the carbon, which led up to an increase in the activated carbon surface hydrophobicity. PA removal varies as a function of the water type, increasing in the order: ground water < surface water ’ ultrapure water < wastewater. The effectiveness of PA adsorption was lower in dynamic than in static regime due to the shorter adsorbent–adsorbate contact time in dynamic regime.
José D. Méndez-Díaz, Mahmoud M. Abdel daiem, José Rivera-Utrilla, Manuel Sánchez-Polo, Isidora Bautista-Toledo, Journal of Colloid and Interface Science 369 (2012) 358–365

B2993 – Removal of nitroimidazole antibiotics from aqueous solution by adsorption/bioadsorption on activated carbon

The objective of the present studywas to analyse the behaviour of activated carbon with different chemical and textural properties in nitroimidazole adsorption, also assessing the combined use of microorganisms and activated carbon in the removal of these compounds from waters and the influence of the chemical nature of the solution (pH and ionic strength) on the adsorption process. Results indicate that the adsorption of nitroimidazoles is largely determined by activated carbon chemical properties. Application of the Langmuir equation to the adsorption isotherms showed an elevated adsorption capacity (Xm = 1.04–2.04 mmol/g) for all contaminants studied. Solution pH and electrolyte concentration did not have amajor effect on the adsorption of these compounds on activated carbon, confirming that the principal interactions involved in the adsorption of these compounds are non-electrostatic. Nitroimidazoles are not degraded by microorganisms used in the biological stage of a wastewater treatment plant. However, the presence of microorganisms during nitroimidazole adsorption increased their adsorption on the activated carbon, although it weakened interactions between the adsorbate and carbon surface. In dynamic regime, the adsorptive capacity of activated carbon was markedly higher in surface water and groundwater than in urban wastewaters.
J. Rivera-Utrilla, G. Prados-Joya, M. Sánchez-Polo, M.A. Ferro-García, I. Bautista-Toledo, Journal of Hazardous Materials 170 (2009) 298–305

B2992 – Modification of activated carbon hydrophobicity by pyrolysis of propene

The chemical nature of the surface of a granular activated carbon has been modified by heat treatment under nitrogen at 1000 ?C followed by pyrolysis of propene in the 300–600 ?C temperature range. Cracking of propene produces deposits of coke on the more reactive sites of the carbon surface, those produced after the decomposition of the original oxygen surface groups along the previous heat treatment. The process leads to an initial reduction in the number of oxygen surface groups and in the capacity of the carbon to chemisorb oxygen. The further growth of the carbon deposit in the interior of the particle decreases the width of the micropore entrance, which is paralleled by the coating of the external surface of the particle. The reduction in the number of active sites of the carbon leads to a decrease in the enthalpy of immersion into polar liquids such as water and ethylenediamine, the carbon becoming more hydrophobic than the original.
M. Gonçalves, M. Molina-Sabio, F. Rodriguez-Reinoso, Journal of Analytical and Applied Pyrolysis 89 (2010) 17–21

B2991 – Oxidation of activated carbon with aqueous solution of sodium dichloroisocyanurate: Effect on ammonia adsorption

An activated carbon has been oxidized with 1–10 wt% aqueous solutions of sodium dichlororisocyanurate (DCI) to introduce oxygen and chlorine surface groups by chemisorption; the formation of chlorine surface groups is important when the concentration of DCI is high, the modification of the microporosity being small. The range of stability of the groups is wide, from groups decomposing at high temperature to HCl to those groups decomposing simultaneously to HCl and CO at low temperature. The carbon with the highest degree of oxidation was heat treated under propene at 200–300 C, this facilitating the removal of chlorine groups; thus, all chlorine groups are lost at 250 C, even those thermally stable up to 800–900 C. The effect of both treatments on both the hydrophilicity and the capacity to retain ammonia has also been studied. Oxidation increases the hydrophilicity of the carbon, as shown by the evolution of water adsorption and the enthalpy of immersion into water. On the other hand, oxidation increases the removal capacity of ammonia both at equilibrium and dynamic tests. However, the contribution of the chlorine surface groups on the adsorption of water and ammonia is small, the groups decomposing to CO2 upon temperature programmed decomposition playing a more important role in the retention of both species.
M. Molina-Sabio, M. Gonçalves, F. Rodríguez-Reinoso, Microporous and Mesoporous Materials 142 (2011) 577–584

B2990 – Water adsorption characteristics of novel materials for heat transformation applications

Within this article we illustrate recent development of sorption materials for heat transformation applications. A broad overview on the possible performance of currently available and recently developed materials ranging from zeolites across aluminophosphates and silicoaluminophosphates to the novel class of metal organic framework materials is given. Materials are evaluated with respect to the use in thermal driven adsorptive heat pumping and cooling applications with water as refrigerant. Therefore a new fingerprinting method is used to evaluate samples under two typical cycle conditions with driving temperatures of 95 °C and 140 °C. A unique aspect is that results can be used for closed as well as for open adsorptive systems. The highest water uptake for driving temperatures of 95 °C was found for an AlPO-18 with 0.253 g/g, which is more than six times higher than the reference silica gel in our comparison. For driving temperatures of 140 °C the highest water uptake was found for the metal organic framework Cu-BTC with 0.324 g/g. Furthermore we give first results on the integral heat of adsorption in the cycle and results of hydrothermal treatment of most promising materials
S.K. Henninger, F.P.Schmidt, H.-M.Henning, Applied Thermal Engineering 30 (2010) 1692-1702

B2989 – Cs exchanged phosphotungstic acid as an efficient catalyst for liquid-phase Beckmann rearrangement of oximes

Cs exchanged phosphotungstic acid is a highly efficient and environmentally benign solid acid catalyst for the liquid-phase Beckmann rearrangement of ketoximes to the corresponding amides. The catalysts CsxH3 xPW12O40 (x = 1.5, 2, 2.5 and 3) were prepared by a titration method. The characterization results indicated that the primary Keggin structure remained intact after exchanging the protons with Cs ions. Moreover, the Cs exchanged catalysts were insoluble and exhibited larger BET surface area than the parent acid. The catalysts exhibited high reactivity and selectivity for the formation of e-caprolactam, the precursor of Nylon 6, from cyclohexanone oxime. The catalyst can be recovered after reaction without any structural transformation
N.R. Shiju, H.M. Williams, D.R. Brown, Applied Catalysis B: Environmental 90 (2009) 451–457

B2988 – Tungstated Zirconia Catalysts for Liquid-Phase Beckmann Rearrangement of Cyclohexanone Oxime: Structure-Activity Relationship

The performance of tungstated zirconia catalysts with different tungsten loadings and calcination temperatures for liquid-phase Beckmann rearrangement of cyclohexanone oxime to ?-caprolactam was studied and the relation of their activity with the structure of tungsten species on zirconia surface was investigated. Cyclohexanone was the major product when zirconia was used as the catalyst while ?-caprolactam was formed in major amounts with tungstated zirconia. The relative amounts of these products depended on the W surface density, and the maximum selectivity to ?-caprolactam was observed at tungsten loadings near that required for the formation of a monolayer. UV-visible absorption edge energies suggested that the surface contains polytungstate species at these loadings. These polytungstate domains create Brønsted acid centers on the surface, as suggested by acidity measurements using NH3 adsorption microcalorimetry and FTIR of adsorbed pyridine, thereby making the tungstated zirconia catalysts active for the formation of ?-caprolactam.
N. R. Shiju, M. AnilKumar, W. F. Hoelderich, D. R. Brown, J. Phys. Chem. C 2009, 113, 7735–7742

B2986 – Mechanistic investigation of hydrothermal aging of Cu-Beta for ammonia SCR

The selective catalytic reduction of NOx with NH3 over a Cu-BEA catalyst was studied after hydrothermal aging between 500 and 900 ?C. The corresponding catalyst was characterized using XPS and XRD techniques in the aging interval of 500, 700 and 800 ?C. No structural changes during the aging process were observed. However, the oxidation state of copper changed during aging and more Cu2+ was formed. We suggest that one of the deactivation mechanisms is the decrease of the Cu+ species. The NO oxidation and NH3 oxidation activity was decreased with increasing aging temperature. Further, we observed that the ammonia oxidation was decreased faster compared to the SCR reactions at low aging temperatures. The experiments from the calorimeter as well as from the ammonia TPD investigations indicate a trend towards more weakly bound ammonia with higher aging temperatures. From the results of the SCR experiments using different NO2/NOx ratios and ammonia oxidation experiments we suggest that most of the N2O is coming from side reactions of the SCR mechanism and not from reactions between NH3 and O2 alone. Interestingly, we observe that after the 900 ?C aging a quite large activity remained for the case with 75% NO2/NOx ratio. The N2O production shows a maximum at 200 ?C, but increases again at higher temperatures. However, the N2O formed at low temperature is decreased after hydrothermal aging while the high temperature N2O is increased. We propose that the different reactions examined in this work do not all occur on the same type of sites, since we observe different aging trends for some of the reactions.
Norman Wilken, Kurnia Wijayanti, Krishna Kamasamudram, Neal W. Currier, Ramya Vedaiyan, Aleksey Yezerets, Louise Olsson, Applied Catalysis B: Environmental 111– 112 (2012) 58– 66

B2978 – Supercritical adsorption of nitrogen on EcoSorb-activated carbon at temperatures up to 383 K and pressures up to 2 MPa

Single adsorption isotherms and differential enthalpies of adsorption of nitrogen were measured on a microporous-activated carbon at various temperatures. A new way for calculating the differential enthalpies of adsorption is presented, and the results obtained were compared to those obtained by the isosteric method derived from the equilibrium data using the Clausius–Clapeyron equation. The measurements were made thanks to a coupled thermostated calorimetric–manometric apparatus which can be operated for pressures up to 2.5 MPa and temperatures from 303 to 423 K. This article provides experimental data which can be used for the adjustment of interaction potential in computational simulations for supercritical adsorption.
Adil Mouahid, David Bessieres, Frédéric Plantier, Gilles Pijaudier-Cabot, J Therm Anal Calorim (2012) 109, 473–479

B2969 – A thermostated coupled apparatus for the simultaneous determination of adsorption isotherms and differential enthalpies of adsorption at high pressure and high temperature

In order to assess and improve the quality of high pressure and temperature adsorption isotherms and differential enthalpies of adsorption on microporous and mesoporous materials, a specific thermostated device comprising a differential heat flow calorimeter coupled with a home-built manometric system has been built. The differential heat flow calorimeter is a Tian Calvet Setaram C80 model which can be operated isothermally, the manometric system is a stainless steel homemade apparatus. The thermostated coupled apparatus allows measurements for pressure up to 2.5 MPa and temperature from 303 to 423 K. Reliability and reproducibility were established by measuring adsorption isotherms on a benchmark sorbent (Filtrasorb F400). A detailed experimental study of the adsorption of pure carbon dioxide and methane has been made on activated carbons (Filtrasorb F400 and EcoSorb); a new procedure for determining the differential enthalpies of adsorption based on the stepwise method is also proposed. The error in the determination of the amount adsorbed is about 3.6%, and the error in the determination of the differential enthalpies of adsorption is 4%.
Adil Mouahid, David Bessieres, Frédéric Plantier, Gilles Pijaudier-Cabot, J Therm Anal Calorim (2012) 109, 1077–1087

B2965 – Review of the molar heats of chemisorption and chemabsorption by crystalline oxides and the surface ‘‘homogeneity versus heterogeneity’’ problem

To obtain a solution of the surface ‘‘homogeneity versus heterogeneity’’ problem, the results of microcalorimetric measurements of the dependences of the molar heats of chemisorption and chemabsorption of different gases on the amounts of chemisorbed or chemabsorbed gases in more than 20 gas/metal-oxide systems, in which the molar chemisorption heats are coverage-independent over rather wide ranges of the surface coverages, are presented. In order to approach the states of the metal oxide samples to those in real catalytic processes catalyzed by these oxides, the coverage dependences of the heats of chemisorption of gases at the samples were measured for a number of gas/metal-oxide systems against the chemisorbed amounts of not only the gas under study but also of another gas chemisorbed previously. The calorimetric dataset is supplemented with data obtained by other methods capable of helping to solve the surface ‘‘homogeneity versus heterogeneity’’ problem. These data are discussed together with the data on chemisorption in more than 40 gas/metal systems for which homogeneity of the surfaces was stated in our previous review. The entire set of the measurements was published for several decades by about 40 different composite authors. The chemisorption and chemabsorption mechanisms are discussed. It is concluded that thermally stabilized powder metal and metal oxide surfaces are homogeneous relative to the chemical ability of their atoms in chemisorption and catalytic processes in line with Langmuir’s opinion and the band theory of solids.
V. E. Ostrovskii

B2955 – Acid–base features of ex-hydrotalcites Mg-containing and Mg-free mixed oxides

CuNiAl and MgCuNiAl mixed oxides (Cu2?/Ni2? = 0.29 and 0.32 mol/mol) were obtained from layered double hydroxide precursors (M2?/Al3? = 2 mol/mol) synthesized by pH-controlled co-precipitation. After structural and textural characterization (by X-ray diffraction and N2 physisorption, respectively), the acid and basic features of the mixed oxides were investigated by adsorption microcalorimetry.NH3 andCO2 were used for probing the acid and basic features, respectively. By the use of temperature-programmed technique, the redox features of the oxides were investigated as well. The behaviour of the oxides as catalysts for the conversion of 4-methylpentan-2-ol at 448, 473, and 523 Kunder atmospheric pressure was studied in a fixed-bed reactor. The dehydration products distribution and the relative extents of the dehydration and dehydrogenation reactions are discussed in terms of the possible occurrence, depending on the lack or presence of Mg in the oxide and the reaction temperature, of either acid–base-governed E1 and E2 mechanisms or Cu-promoted reaction pathways.
D. Meloni, M. F. Sini, M. G. Cutrufello, R. Monaci, E. Rombi, I. Ferino, J Therm Anal Calorim, 2012

B2954 – Characterization of the active sites in MgNiAl mixed oxides by microcalorimetry and test reaction

In this study, MgNiAl mixed oxides derived from layered double hydroxide precursors were prepared by pH-controlled co-precipitation. Three samples were prepared with a (Mg2+ + Ni2+)/Al3+ ratio of 2 and a Ni2+/Mg2+ with ratios of 0.22, 0.47, and 4.05. The structural, textural and redox features of the oxides were investigated by a variety of techniques, including X-ray diffraction, transmission electron microscopy, N2 physisorption, and temperature-programmed reduction. The acid and base properties were assessed by NH3 and CO2 adsorption microcalorimetry, respectively. The acid–base features were also investigated by testing the catalytic behaviors of the oxides for the conversion of 4-methylpentan-2-ol under both mild and stressed conditions. The reactant alcohol can undergo dehydration into 4-methylpent-1-ene, 4-methyl-pent-2-ene, and skeletal isomers of C6-alkenes, as well as dehydrogenation to 4-methylpentan-2-one and higher ketones, the product selectivity being governed by the concentration and strength of the acid and base sites. Comparison between the calorimetric and test reaction results is discussed.
D. Meloni, M. F. Sini, M. G. Cutrufello, R. Monaci, E. Rombi, I. Ferino, J Therm Anal Calorim (2012) 108, 783–791

B2952 – Adsorption heats of phenol on activated carbon using adapted method of immersion calorimetry

Simple adaptation of the technique of immersion calorimetry enables determining both integral and differential adsorption heats as well as the course of the adsorption isotherm of phenol on activated carbon. The innovative aspect of the applied procedure consists in bringing the phenol aqueous solution to contact with the suspension of carbon with water. Thus, the ‘‘interfering’’ heat effect of carbon interaction with water is eliminated, and only the net adsorption heat of phenol is monitored. The value of -52.5 kJ mol-1 was ascertained as the molar differential adsorption heat at the low surface coverage (cca 0.2 mmol g-1) of the sample of microporous carbon.As the adsorption process continues, for adsorption uptakes exceeding the value of about 1 mmol g-1, molar differential adsorption heats appear to be established at a level of about -20 ± 5 kJ mol-1.
Boleslav Taraba, J Therm Anal Calorim (2012) 107:923–926

B2886 – Influence of the metal function in the “one-pot” synthesis of 4-methyl-2-pentanone (methyl isobutyl ketone) from acetone over palladium supported on Mg(Al)O mixed oxides catalysts

Pd/Mg(Al)O samples (0.05 < Pd < 0.5 wt%) were evaluated in the gas phase reaction of acetone with hydrogen to methyl isobutyl ketone (MIBK). The catalysts were prepared by impregnating a calcined Mg–Al layered double hydroxide with Pd acetylacetonate in toluene solution. The highest selectivity to MIBK was achieved with ca. 0.2 wt% Pd and size of Pd particles of ca. 3–5 nm.
Nigamananda Das, Didier Tichit, Robert Durand, Patrick Graffin, Bernard Coq, Catalysis Letters Vol. 71, No. 3-4, 2001

B2885 – Statistical quantification of the influence of material properties on the oxidation and ignition of activated carbons

The influence of material properties on the reactivities of activated carbon materials have been studied on a laboratory scale. Carbon samples having diversified origin and properties were characterized using a thermogravimetry (TG) coupled with a differential scanning calorimetry (DSC). Reactivity parameters like the Point of Initial Oxidation (PIO) representing the beginning of the oxidation reactions and the Spontaneous Ignition Temperature (SIT) where the bed combustion takes place in a self sustaining manner were experimentally determined. The intrinsic properties of the activated carbons influencing oxidation and ignition were examined qualitatively followed by quantitative statistical correlations. Results from both qualitative and statistical correlations showed that increase in the oxygen content in the form of surface oxygenated groups increased the reactivity of activated carbons. It was by far the single most influential property discriminated from the analysis. The porosity characteristics like the specific surface area and pore volume did show some vague trends but could not be validated like that of the oxygen content. The effects of these individual properties on the oxidation and ignition reactivity are discussed.
Thangavelu Jayabalan, Pascaline Pré, Valérie Héquet, Pierre Le Cloirec, Adsorption (2008) 14, 679–686

B2883 – Low-temperature Oxidation of Carbon Monoxide on Co/ZrO2

A 10%Co/ZrO2 catalyst prepared by impregnation was tested for its activity for the oxidation of CO to CO2 in excess oxygen. Activity tests showed that conversion could be obtained at temperatures as low as 20 °C. Time-on-stream studies showed no loss of activity in these experiments, indicating that this catalyst is stable in the experimental oxidizing conditions. The activation energy for the CO to CO2 oxidation reaction was calculated as Ea = 54 kJ/mol over this catalyst. Characterization of the material by thermogravimetric analysis, temperature-pro- grammed techniques, X-ray photoelectron spectroscopy, and laser Raman spectroscopy indicate that Co3O4 is present on monoclinic ZrO2 after the calcination of the catalyst.
Matthew M. Yung, Erik M. Holmgreen, Umit S. Ozkan, Catal Lett (2007) 118, 180–186

B2882 – Adsorption/Desorption Behavior of Ethanol Steam Reforming Reactants and Intermediates over Supported Cobalt Catalysts

The interactions of reactants and intermediates with the surfaces in ethanol steam reforming over Co catalysts supported on ZrO2 and CeO2 were investigated using Temperature Programmed Desorption, Thermogravimetric Analysis-Differential Scanning Calorimetry (TGA-DSC), in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) and isotopic labeling techniques. Possible mechanistic steps are proposed that lead to acetaldehyde and acetone formation, steam reforming and coking. The role of the support versus active metal (i.e., Co) and the involvement of water in the reaction network are discussed.
Hua Song, Xiaoguang Bao, Christopher M. Hadad, Umit S. Ozkan, Catal Lett (2011) 141, 43–54

B2881 – Efficient catalysts for olefins from alkanes: sol–gel synthesis of high surface area nano scale mixed oxide clusters

High surface area nano scale Li/MgO oxide clusters with low lithium loadings are prepared by sol–gel method. Appreciable amounts of lithium present can be incorporated into the magnesia gel during preparation and retained in the oxide matrix after gel combustion. This limits presence of free lithium phases and helps prevent the associated sintering and loss of surface area during thermal treatments. The sol–gel method also allows to circumvent the high temperature treatments necessary to incorporate lithium into the magnesia oxide matrix, a prerequisite for the formation of [Li+O)] type defect sites which are the catalytically active sites for oxidative dehydrogenation of alkanes.
C. Trionfetti, I.V. Babich, K. Seshan, L. Lefferts, Topics in Catalysis Vol. 39, Nos. 3–4, October 2006

B2880 – A New Method for the Determination of Low Coverage Adsorption Heats for Zeolite-VOC Systems

In this paper, we present a newexperimental technique and a mathematical procedure for the calculation of the isosteric heats of adsorption of VOC-zeolite systems. This procedure provides a continuous isosteric heat curve over a large coverage ratio range including the low-coverage area. Results are given for a toluene-NaY system at 423 K. The validity of the method is discussed by comparison with other methods.
Joëlle Nokerman, Xavier Canet, Guy De Weireld, Marc Frere, Adsorption 11, 121–125, 2005

B2879 – Determination of the Micropore Volume Distribution Function of Activated Carbons by Gas Adsorption

A new method for the determination of the micropore volume distribution function of activated carbons is presented. It is based on the treatment of pure gas adsorption isotherms by a theoretical model derived from the Hill-de Boer theory. Adsorption data (isotherms and heat curves) for carbon dioxide, ethane and ethylene on activated carbon (F30/470 CHEMVIRON CARBON) have been provided by a thermobalance coupled to a calorimeter (TG-DSC 111 SETARAM) at different temperatures (233, 273, 303 and 323 K) for pressures up to 100 kPa. Adsorption isotherms of carbon dioxide and ethane at 303 and 323 K have been used for the determination of the micropore volume distribution function of the activated carbon of interest. The knowledge of its structure has then allowed the simulation of adsorption isotherms and heats for the same adsorbates at the same temperatures as those experimentally studied. Similar calculations have been conducted for ethylene. Whatever the adsorbate carbon dioxide and ethane used for the determination of the micropore volume distribution function or ethylene), the mean deviation between experimental and calculated isotherms does not exceed 4% at quasicritical and supercritical temperatures (303 and 323 K). In the same temperature conditions, discrepancies between calculation and experiment reach about 10% for adsorption heats. For both isotherms and heats, large discrepancies appear at low temperature (233 and 273 K). This method allows the determination of the micropore volume distribution function of activated carbons. The validity of the results is insured using several isotherms of several adsorbates and taking into account the calorimetric effect of the phenomenon. That is the reason why this method can also be seen as a new possible model for pure gas adsorption data prediction. This paper also presents a brief summary of the state of the art in this field.
Marc Frere, Roger Jadot, Jacques Bougard, Adsorption 3, 55-65 (1996)

B2874 – The Mechanistic Study of Methane Reforming with Carbon Dioxide on Ni/a-Al2O3

The reactions of oxidized and reduced 6 wt % NiO/?-Al2O3 with H2, CH4, CO2, O2, and their mixtures are studied in flow and pulse regimes using a setup equipped with a differential scanning calorimeter DSC-111 and a system for chromatographic analysis. It is shown that treatment with hydrogen at 700°C results in the partial reduction of NiO to Ni. Methane practically does not react with oxidized Ni/?-Al2O3 but it does react actively with the reduced catalyst to form H2 and surface carbon. The latter is capable of reacting with lattice oxygen of Ni/?-Al2O3 (slowly) and with adsorbed oxygen (rapidly). Carbon dioxide also reacts with surface carbon to form CO (rapidly) and with metallic Ni to yield CO and NiO (slowly). Thus, the main route of methane reforming with carbon dioxide on Ni/?-Al2O3 is the dissociative adsorption of CH4 to form surface carbon and H2 and the reaction of this carbon with CO2 resulting in the formation of CO by the reverse Boudouard reaction. Side routes are the interaction of the products of methane chemisorption with catalyst oxygen and the dissociative adsorption of CO2 on metallic nickel. A competitive reaction of surface carbon with adsorbed oxygen results in a decrease in the CO2 conversion in methane reforming with carbon dioxide. Therefore, the presence of gaseous oxygen in the reacting mixture decelerates methane reforming (catalyst poisoning by oxygen).
V. Yu. Bychkov, O. V. Krylov, V. N. Korchak, Kinetics and Catalysis, Vol. 43, No. 1, 2002, pp. 86–94

B2873 – Gold catalysts supported on ceria-modified mesoporous zirconia for low-temperature water–gas shift reaction

New gold catalytic system prepared on ceria-modified mesoporous zirconia used as water–gas shift (WGS) catalyst is reported. Mesoporous zirconia was synthesized using surfactant templating method through a neutral [C13(EO)6-Zr(OC3H7)4] assembly pathway. Ceria modifying additive was deposited on mesoporous zirconia by deposition–precipitation method. Gold-based catalysts with different gold content (1–3 wt. %) were synthesized by deposition–precipitation of gold hydroxide on mixed metal oxide support. The supports and the catalysts were characterized by powder X-ray diffraction, high-resolution transmission electron microscopy, N2 adsorption analysis and temperature programmed reduction. The catalytic behavior of the gold-based catalysts was evaluated in WGS reaction in a wide temperature range (140–300 °C) and at different space velocities and H2O/CO ratios. The influence of gold content and particle size on the catalytic performance was investigated. The WGS activity of the new Au/ceria-modified mesoporous zirconia catalysts was compared with that of gold catalysts supported on simple oxides CeO2 and mesoporous ZrO2, revealing significantly higher catalytic activity of Au/ceria-modified mesoporous zirconia. A high degree of synergistic interaction between ceria and mesoporous zirconia and a positive modification of structural and catalytic properties by ceria have been achieved. It is clearly revealed that the ceria-modified mesoporous zirconia is of much interest as potential support for gold-based catalyst. The Au/ceria-modified mesoporous zirconia catalytic system is found to be effective catalyst for WGS reaction.
V. Idakiev, T. Tabakova, K. Tenchev, Z.-Y. Yuan, T.-Z. Ren, B.-L. Su, J Porous Mater (2012) 19, 15–20

B2864 – Influence of Cobalt in Gold Catalysed Gas Phase Propene Epoxidation: Enhancement of Au Uptake and Catalyst Activity

Modification of Au/TS-1 catalysts with cobalt resulted in a strong increase in the formation rate of propene oxide in the direct gas-phase propene epoxidation using a H2/O2 mixture as oxidant. A detailed investigation of these Au–Co/TS-1 catalysts by means of ICP, XPS, TEM and microcalorimetry revealed that this effect is mainly due to the higher gold uptake during deposition–precipitation. In contrast to TiO2 supported gold catalysts with a similar metal content, Au–Co/TS-1 showed an extraordinary stability in terms of deactivation at a low reaction temperature of 125 °C not reported before.
Christina Mennemann, Peter Claus, Catal Lett (2010) 134, 31–36

B2857 – Formation of the Ni–CrOx/MgO and Ni/MgO Catalysts for Carbon Dioxide Reforming of Methane

Temperature-programmed reduction by hydrogen, temperature-programmed desorption of O2, local X-ray spectral analysis, and scanning electron microscopy are used to study redox processes occurring on the Ni–Cr2O3/MgO and Ni/MgO catalysts for carbon dioxide reforming of methane. The reduction of Ni/MgO leads to the formation of nickel clusters distributed over the surface of MgO. During the reduction of NiO?Cr2O3/MgO, chromates are transformed into chromites, and then nickel is formed by the reduction of spinel NiCr2O4. Reoxidation leads to the oxidized structures NiO, NiCr2O4, and NiCrO4.
V. Yu. Bychkov, V. N. Korchak, O. V. Krylov, O. S. Morozova, T. I. Khomenko, Kinetics and Catalysis, Vol. 42, No. 4, 2001, pp. 561–573

B2856 – Changes in the Composition, Structure, and Activity of Catalysts in Hydrogenation of Diene Hydrocarbons of the C5 C9 Fraction of Pyrolysis Naphtha

A comparative study was performed of changes in the composition, structure, and catalytic activity of catalysts in selective hydrogenation of C5!C9 fraction of pyrolysis naphtha. The main reasons for catalyst deactivation in the course of industrial exploitation were considered
A. A. Lamberov, R. G. Romanova, E. Yu. Sitnikova, Kh. Kh. Gilmanov, S. V. Trifonov, Russian Journal of Applied Chemistry, Vol. 76, No. 2, 2003, pp. 229 233

B2853 – Effect of the Support and the Reduction Temperature on the Formation of Metallic Nickel Phase in Ni/Silica Gel Precursors of Vegetable Oil Hydrogenation Catalysts

Ni/SiO2 materials with identical composition (SiO2/Ni = 1.0) have been synthesized by precipitation of Ni(NO3)2 · 6H2O solution with Na2CO3 solution on the silica gel, obtained at three different pH values. The present investigation was undertaken in an endeavor to study the effects of the silica gel support type and the reduction temperature on the formation and dispersion of the metallic nickel phase in the reduced Ni/SiO2 precursors of the vegetable oil hydrogenation catalyst. The physicochemical characterization of the unreduced and reduced precursors has been accomplished appropriately by powder X-ray diffraction, infrared spectroscopy, temperature programmed reduction and H2-chemisorption techniques. It can be stated that the texture peculiarities of the silica gels used as supports influence on the crystalline state and distribution of the deposited Ni-containing phases during the preparation of the precursors, on the reduction temperature of the investigated solids as well as on the bulk size and surface dispersion of the arising metallic nickel particles. It was shown that two types of Ni2+-species are formed during the synthesis procedure, namely basic nickel carbonate-like and Ni-phyllosilicate with different extent of presence, location and strength of interaction. The different location of these species is supposed to result in various strength of Ni–O and Ni–O–Si interaction, thus determining the overall reducibility of the precursors. It was specified that the Ni2+-species are strongly bonded to the surface of the silica gel obtained at neutral pH value and weakly bonded to the surface of those prepared in acidic and alkaline conditions. It was established that the precursor, derivates from the silica gel obtained at alkaline conditions, demonstrates both significant reduction of the Ni2+ ions at 430°C and finely dispersed metallic nickel particles on its surface. High dispersion of the metallic nickel might be the crucial reason for achieving of high activity in the vegetable oil hydrogenation.
M. Gabrovska, J. Krsti, P. Tzvetkov, K. Tenchev, M. Shopska, N. Vukeli, D. Jovanovic, Russian Journal of Physical Chemistry A, 2011, Vol. 85, No. 13, pp. 2392–2398

B2852 – Microcalorimetry in the identification and characterization of the most reactive active sites of heterogeneous catalysts

The microcalorimetric technique has been applied to investigate the strongest active sites of zeolites, heteropolyacids and perovskites. The differential heats of adsorption of carbon monoxide, ammonia and oxygen were determined. The results imply that the method is very useful in the identification and characterization of the most reactive active sites of solid catalytic materials.
Vesna Rakic, Vera Dondur, Ubavka Mioc, Dusan Jovanovic, Topics in Catalysis Vol. 19, Nos. 3–4, May 2002

B2849 – Glycerol Valorization: Dehydration to Acrolein Over Silica-Supported Niobia Catalysts

The catalytic dehydration of glycerol to acrolein is investigated over silica-supported niobia catalysts in a continuous fixed-bed gas-phase reactor. Various supported niobia catalysts are prepared and characterized using surface analysis and spectroscopic methods (XRD, UV–Vis, XPS, N2 adsorption), as well as with ammonia adsorption microcalorimetry. Good results are obtained with initial glycerol conversions of over 70% and with 50–70% selectivity to acrolein. We investigate the influence of changing the catalyst acid strength by varying the niobia content and catalyst calcination temperature. Glycerol conversion and acrolein selectivity depend on the surface acid strength. Catalyst deactivation by coking is also observed, but simple oxidative treatment in air restores the activity of the catalysts completely.
N.R. Shiju, D. R. Brown, K. Wilson, G. Rothenberg, Top Catal (2010) 53, 1217–1223

B2839 – Characterization of monofunctional ZrO2–MoO3 catalysts for methylcyclopentane conversion

A series of ZrO2–MoO3 catalysts with different molybdenum loadings (0–18.7 at.% Mo) prepared by co-precipitation were characterized and evaluated for their performance for methylcyclopentane (mcp) conversion. The dependence of Mo content on the crystallinity, surface area, and acidic properties of ZrO2–MoO3 is studied and evaluated as a function of molybdenum loading. The monoclinic phase is observed at low Mo loadings, with the tetragonal polymorph of ZrO2 effectively stabilized at higher Mo loadings. The surface area of ZrO2–MoO3 increases with molybdenum content to a maximum value of 124m2 g?1 at a loading of 15.8 at.% Mo, followed by a decrease at higher Mo loadings. Isothermal CO2 adsorption and ammonia TPD results indicate the strength of basic sites and specific NH3 desorption decreases with increasing molybdenum content, while TPR indicates ZrO2–MoO3 catalysts are more easily reduced with increasing molybdenum loading. The most active catalyst for mcp conversion (36% conversion) corresponds to a molybdenum loading of 3.2 at.% Mo, which has the highest acidity per surface area of the ZrO2–MoO3 catalysts studied
Carolyn Kenney, Yadollah Maham, Alan E. Nelson, Thermochimica Acta 434 (2005) 55–61

B2771 – The Heats of Exchange of Transition Metal Ions on the Na Form of Clinoptilolite

Direct calorimetric measurements were used to determine the heats of exchange of the Mn2+, Co2+, Cu2+, and Ni2+ cations on the Na form of clinoptilolite over the entire range of solid phase fillings with sorbed cations. In parallel, ion exchange isotherms for the systems were measured by the sorption-analytic method. The integral free energies and entropies of ion exchange were calculated. It was shown that the solution phase of the clinoptilolite–electrolyte solution two-phase system contributed significantly to the total thermodynamic characteristics of ion exchange. The differentiation of the dependence of the integral enthalpy on the degree of filling was performed to show that the clinoptilolite structure contained at least two types of exchange sites having different interaction energies with transition metal ions.
Yu. I. Tarasevich, D. A. Krysenko, V. E. Polyakov, E. V. Aksenenko, Russian Journal of Physical Chemistry A, 2008, Vol. 82, No. 9, pp. 1506–1511

B2770 – The reaction of oxygen with CO complexes on calcium oxide and magnesium oxide

The heat evolved during the adsorption and oligomerization of CO on outgassed CaO and MgO has been determined with a heatflow calorimeter. The chemisorbed complexes formed include highly-conjugated (CO)2?n anions which impart colour to the oxides. The reaction of these complexes with oxygen has been quantified calorimetrically and correlated with changes observed spectroscopically
Michael Bailes, Frank S. Stone, Topics in Catalysis 11/12 (2000) 213–222

B2767 – Acidities and catalytic activities of persulfonated poly(styrene-co-divinylbenzene) ion-exchange resins

A series of macroporous sulfonated poly(styrene-co-divinylbenzene) ion-exchange resins with varying levels of sulfonation have been prepared. The acidities of these resins have been measured calorimetrically by ammonia sorption. Catalytic activities have been measured in two liquid-phase reactions: the dehydration of 1-hexanol under flow conditions and the hydration of propene as a batch process. The molar enthalpies of ammonia sorption show that the strength of the acid sites increases as the level of sulfonation is increased; catalytic activities follow the same trend. The most active resins are those that have been sulfonated at levels above one sulfonic acid group per aromatic ring (“persulfonated”). These persulfonated resins also show higher thermal stabilities than conventional resins (sulfonated at just below one acid group per aromatic ring).
M. Hart, G. Fuller, D.R. Brown, C. Park, M.A. Keane, J.A. Dale, C.M. Fougret, R.W. Cockman, Catalysis Letters Vol. 72, No. 3-4, 2001

B2763 – Preparation of Mesoporous V–Ce–Ti–O for the Selective Oxidation of Methanol to Dimethoxymethane

Mesoporous V–Ce–Ti–O oxides were synthesized through the combination of sol–gel and hydrothermal methods and were characterized by different techniques. N2 adsorption showed that the mesoporous oxides with 0–20 wt.% V2O5 possessed the surface areas of about 160 m2 g-1 with narrow pore size distribution centered around 4–5 nm. Vanadium species were highly dispersed in the samples, as confirmed by the wide angle XRD and Raman spectroscopy. The surface acidity of the materials was determined by the microcalorimetric adsorption of NH3. Temperature programmed reduction and O2 chemisorption were used to probe the redox property of the materials. It was found that the mesoporous V–Ce–Ti–O possessed bifunctional characters of acidic and redox properties that catalyzed the oxidation of methanol to dimethoxymethane (DMM). These bifunctional characters were further enhanced by the addition of V2O5 and SO4 2- onto V–Ce–Ti–O simultaneously. Such supported catalysts exhibited excellent performance for the selective oxidation of methanol to DMM. Specifically, 72% conversion of methanol with 85% selectivity to DMM was achieved at 423 K over a SO4 2-–V2O5/V–Ce–Ti–O catalyst.
Jingwei Liu, Qing Sun, Yuchuan Fu,,Hongying Zhao, Aline Auroux, Jianyi Shen, Catal Lett (2008) 126,155–163

B2756 – Role of B5-Type Sites in Ru Catalysts used for the NH3 Decomposition Reaction

A series of activated carbon supported Ru catalysts have been reduced at different temperatures under hydrogen flow, and in some cases under ammonia flow, in order to modify the morphology and the particle size of the metallic active sites. CO chemisorption and transmission electron microscopy have been applied to follow the variations of these particles. The samples have been tested in the ammonia decomposition reaction, where systematic differences in catalytic activities as consequence of the support modification as well as due to the changes in the Ru particle sizes have been detected. Furthermore when potassium is added as catalyst promoter the sintering of Ru particles is significantly diminished and thus the changes in catalytic activities are inhibited. The electronic states of the Ru particles have been evaluated by determination of the chemisorption heats of the CO probe molecule. A part of other promoter or support effects it seems to exit a critical mean size for Ru particles on where maximum of catalytic activity is achieved. This behavior can be rationalized by the presence of surface highly active B5 sites, which consist of an arrangement of three Ru atoms in one layer and two further Ru atoms in an internal layer. These especial surface sites are expected to be in a higher proportion over Ru crystallites of those critical sizes, namely for Ru diameter sizes in the rage of 3–5 nm.
F. R. Garc?a-Garc?a, A. Guerrero-Ruiz, I. Rodr?guez-Ramos, Top Catal (2009) 52, 758–764

B2755 – Surface sites on carbon-supported Ru, Co and Ni nanoparticles as determined by microcalorimetry of CO adsorption

The adsorption of CO on carbon-supported metal (Ru, Co and Ni) catalysts was studied by microcalorimetry. A correlation of the results thus obtained with those reported for monocrystals or with other studies available in the scientific literature for supported metal catalysts, including infrared spectroscopy data, enables the determination of the type of exposed crystalline planes and/or of the different types of CO adsorbed species. The results obtained suggest that the energetic distribution of the surface sites depends on the carbon support material and on the applied reduction treatment. In this way, the use of a high surface area graphite (clean of surface oxygen groups) leads to an electron density enrichment on the small metal particles (Ru) and, in general, to a higher heterogeneity of the active surface sites. The elimination of surface oxygen functional groups (with the reduction treatment at the higher temperature) of the carbon molecular sieve support leads to changes in the surface structure of the metal particles and, consequently, to higher CO adsorption heats, particularly for Ru and Co.
M. Cerro-Alarcona, A. Maroto-Valiente, I. Rodr?guez-Ramos, A. Guerrero-Ru?z, Thermochimica Acta 434 (2005) 100–106

B2754 – Changes in the selective hydrogenation of citral induced by copper addition to Ru/KL catalysts

Bimetallic Ru–Cu catalysts supported on KL zeolite have been prepared by coimpregnation with ionic precursors and characterized by several methods, such as temperature-programmed reduction, CO and hydrogen chemisorption, nitrogen adsorption, infrared spectroscopy of chemisorbed CO and microcalorimetry of CO adsorption. The catalytic behavior of the samples was analyzed in the selective hydrogenation of citral in the liquid phase, at 323 K and 5 MPa. The presence of bimetallic entities as well as of segregated copper species was recognized by the TPR measurements. The CO-FTIR and microcalorimetry results evidence that the higher the Cu/Ru atomic ratio the larger the surface heterogeneity, with formation of Cu?+ species. Bimetallic catalysts are more active than the monometallic ruthenium catalyst in the hydrogenation of citral, but this activity decreases with the increasing of copper concentration. In addition, selectivity towards citronellal decreases as the copper content increases, in opposite trend to the selectivity toward geraniol and nerol. For low copper loading (Cu/Ru 0.4) formation of a surface alloy is discussed. This surface structure is particularly active for hydrogenation of the conjugated C=C double bond of citral. For Cu/Ru = 0.8 and Cu/Ru = 1.2 samples, three-dimensional islands of segregated copper seem to cover, in part, the surface alloy. This latter surface structure is less active than the preceding one for hydrogenation of the C=C double bond, but more selective for hydrogenation of the C=O group of citral.
J. Alvarez-Rodr?guez, A. Guerrero-Ruiz, I. Rodriguez-Ramos, A. Arcoya, Microporous and Mesoporous Materials 110 (2008) 186–196

B2753 – Study of CO chemisorption on graphite-supported Ru–Cu and Ni–Cu bimetallic catalysts

The adsorption of CO on graphite-supported monometallic catalysts (Ni and Ru) and bimetallic catalysts (Ru–Cu and Ni–Cu) reduced at different temperatures was studied by microcalorimetry. The calorimetric profiles obtained over these two bimetallic systems provides information about the different types of interaction (bridged, linear or subcarbonyl species) that could exist in the bimetallic system when Cu was introduced in the Ru and Ni monometallic catalysts.
E. Asedegbega-Nieto, A. Guerrero-Ru?z, I. Rodr?guez-Ramos, Thermochimica Acta 434 (2005) 113–118

B2750 – Calculation of Contact Angle for Hydrophobic Powders Using Heat of Immersion Data

Heat of immersion (¢Him) data are frequently used to investigate the surface characteristics of solids. In this study, the relationship between the heat of immersion and the contact angle is established from first principles for hydrophobic powders. The heat of immersion of three fluorinated carbons in water is obtained by extrapolating the ¢Him data obtained for dilute mixtures of 1-propanol and water to the point of pure water. The ¢Him values for pure water are then used to calculate the contact angle associated with the hydrophobic powders.
David A. Spagnolo, Yadollah Maham, and Karl T. Chuang, J. Phys. Chem. 1996, 100, 6626-6630

B2747 – Alkylation of phenols and naphthols on silica-immobilized triflate derivatives

Immobilized triflate derivatives (LaðOTf Þ3, AgOTf, tert-butyldimethylsilyltrifluoro-methanesulfonate), and triflic acid were found to be effective in the alkylation of phenol and naphthols with tert-butanol. The acidic strength and type of acidity (Lewis or Brønsted) are key factors controlling the conversion and product distribution.
Bogdan C. Gagea, , Andrei N. Parvulescu, Vasile I. Parvulescu, Aline Auroux, Paul Grange, Georges Poncelet, Catalysis Letters Vol. 91, Nos. 1–2, November 2003

B2746 – Can alkane isomers be separated? Adsorption equilibrium and kinetic data for hexane isomers and their binary mixtures on MFI

In this study we present a global overview of the adsorption behavior of hexane isomers on MFI. With an experimental approach that couples a manometric technique with Near Infrared (NIR) spectroscopy, which has been recently developed, we did address adsorption kinetic properties of n-hexane, 2-methylpentane, 2,2-dimethylbutane and 2,3-dimethylbutane, and their binary mixtures. The adsorption equilibrium properties of the binary mixtures were also assessed using the same technique. Whereas the adsorption isotherms and heats of adsorption for single components have been studied by a manometric technique coupled with a micro calorimeter. The differential heats of adsorption of n-hexane increase slightly with loading, on the other hand the heat of adsorption of branched hexanes exhibits a decrease with loading. The diffusion rates on MFI of n-hexane, 2-methylpentane and 2,3-dimethylbutane are in the same order of magnitude. However, the diffusion rate of 2,2-dimethylbutane is two orders of magnitude lower than rates of the other isomers. In the binary mixtures the components interact and the difference between the diffusion rates of the components decreases. TheMFI zeolite presents equilibrium selectivity towards the less branched isomers. In conclusion, a separation process for linear/mono-branched alkanes + double-branched alkanes, has to be based on its equilibrium properties and not based on adsorption kinetics.
Alexandre F.P. Ferreira, Marjo C. Mittelmeijer-Hazeleger, Alfred Bliek, Adsorption (2007) 13, 105–114

B2743 – Effect of sulfation on the acid-base properties of tetragonal zirconia. A calorimetric and IR spectroscopic study

The RT adsorption of CO2 was studied in order to compare the surface acid-base properties of yttria-stabilized tetragonal ZrO2, either plain or variously sulfated. The nature of the species formed upon CO2 adsorption, as well as their stability upon outgassing, was monitored by IR spectroscopy, whereas the population of the sites and their energy distribution was studied by microcalorimetry. The effect of sulfation on the basicity of cus Zr4+/O2ÿ pairs and on the Lewis acidic strength of cus Zr4þ cations, as well as the influence of calcination on the amount and nature of surface sulfates were studied and correlated with the catalytic activity of SZ systems.
Vera Bolis, Giuliana Magnacca, Giuseppina Cerrato, Claudio Morterra, Topics in Catalysis Vol. 19, Nos. 3–4, May 2002

B2742 – Entrapping molecules in zeolites nanocavities: a thermodynamic and ab-initio study

Adsorption enthalpies of Ar, N2, CO, H2O, CH3CN and NH3 on H-BEA and H-MFI zeolites and on Silicalite, have been measured calorimetrically at 303K in order to assess the energetic features of dispersive forces interactions (confinement effects), H-bonding interactions with surface silanols and specific interactions with Lewis and Brønsted acidic sites. The adsorption of the molecular probes with model clusters mimicking surface silanols, Lewis and Brønsted sites has been simulated at ab-initio level. The combined use of the two different approaches allowed to discriminate among the different processes contributing to the measured (??adsH). Whereas CO and N2 single out contributions from Lewis and Brønsted acidic sites, Ar is only sensitive to confinement effects. For H2O, CH3CN and NH3 the adsorption on Brønsted sites is competitive with the adsorption on Lewis sites. The energy of interaction of H2O with all considered zeolites is surprisingly higher than expected on the basis of ??adsH vs PA correlation.
V. Bolis, A. Barbaglia, M. Broyer, C. Busco, B. Civalleri, P. Ugliengo, Origins of Life and Evolution of the Biosphere 34, 69–77, 2004

B2741 – Ni-based xero- and aerogels as catalysts for nitroxidation processes

Porous nanocomposites made out of nickel dispersed on silica or alumina matrices were prepared as prospective catalysts for the nitroxidation of hydrocarbons in the form of aerogel or xerogel by adopting either a supercritical or a conventional gel drying procedure. The structural and textural features of the materials were investigated by X-ray diffraction, transmission electron microscopy and N2 physisorption and combined to the acid/base and reducibility data as deduced by adsorption microcalorimetry and temperature programmed reduction (TPR) profiles. The alumina-based samples are made out of nanocrystalline nickel aluminate and are mesoporous, although the aerogel has larger pore volumes and surface area than the xerogel. On the other hand, in the silica-based samples nickel oxide nanocrystals are dispersed on amorphous silica, the size of the nanocrystals being around 5 nm in the microporous xerogel and 14 nm in the mainly mesoporous aerogel. TPR data point out that the alumina-based samples have similar reducibility, whereas significant differences were observed in the silica-supported composites, the NiO–SiO2 aerogel exhibiting improved reducibility at low temperature. The NO-catalyst interaction was monitored by temperature programmed NO reaction coupled to mass spectrometry and preliminary tests on the use of the NiO–SiO2 xerogel and aerogel nanocomposites for the catalytic nitroxidation of 1-methyl-naphthalene to 1-naphthonitrile were obtained in a fixed-bed continuous-flow reactor. The data indicate that the aerogel exhibits larger selectivity than the corresponding xerogel, pointing out the importance of tuning the sol–gel parameters in the design of porous composite materials for catalytic applications
Maria Giorgia Cutrufello, Elisabetta Rombi,,Italo Ferino, Danilo Loche, Anna Corrias, Maria Francesca Casula, J Sol-Gel Sci Technol (2011) 60, 324–332

B2740 – Acid-base properties of zirconium, cerium and lanthanum oxides by calorimetric and catalytic investigation

The combined use of calorimetric and catalytic methods for the investigation of the acid-base properties of oxide systems is discussed with reference to the authors’ work on pure and doped zirconia samples, ceria-zirconia and ceria-lanthana solid solutions. Adsorption microcalorimetry of ammonia and carbon dioxide had been used to characterize the samples, whose chemical and thermal history was taken into account. The catalytic behavior of these samples in the conversion of 4-methylpentan-2-ol, route to 4- methylpent-1-ene (starting product for the manufacture of polymers of superior technological properties), had also been studied. On the basis of the calorimetric data, a rationale for interpreting the data for the transformation of 4-methylpentan-2-ol is formulated, which takes into account the role of the concentration and strength of the sites in governing the competition among the various mechanisms for dehydration and dehydrogenation.
M.G. Cutrufello, I. Ferino, R. Monaci, E. Rombi, V. Solinas, Topics in Catalysis Vol. 19, Nos. 3–4, May 2002

B2739 – Mise au point d’un dispositif couplé manométrique-calorimétrique pour l’étude de l’adsorption de fluides supercritiques dans des milieux microporeux et mésoporeux

Au cours de ce travail, un dispositif de mesure couplé manométrique-calorimétrique a été développée pour déterminer simultanément les isothermes et les enthalpies d’adsorption dans des intervalles élevés de pression et température. Ce dispositif couplé comprend un calorimètre Calvet C80 (de setaram) associé à un dispositif manométrique développé in-situ. Il permet d’étudier les phénomènes d’adsorption de gaz sur des solides poreux pour des températures comprises entre 303.15K à 423.15K et des pressions comprises entre 0 et 2.5MPa. Dans un premier temps, une description complète de l’appareillage et des protocoles expérimentaux sont exposés. Dans un second temps, la fiabilité et la reproductibilité de ce dispositif a été testée en réalisant des mesures sur un échantillon poreux benchmark (Filtrasorb F400) `a 318.15K. Les mesures ont été complétées, à différentes températures, avec celles obtenues par méthode gravimétrique afin d’établir des informations à haute température et haute pression. Ces dispositifs ont permis d’étudier l’adsorption de fluide supercritique (azote N2, méthane CH4, dioxyde de carbone CO2) dans des charbons actifs et des silices microporeuse ou mésoporeuse. L’adsorption du méthane dans une roche de type (TGR) a été également étudiée. Ces résultats expérimentaux sont utilisés pour l’étude des interactions fluide/substrat `a prendre en compte dans la simulation moléculaire ou la théorie DFT.
Adil Mouahid, Thèse Université de Pau et des Pays de l’Adour, 2010

B2738 – Catalytic Reforming of Methane by Carbon Dioxide over Nickel-Exchanged Zeolite Catalysts

A series of nickel-exchanged catalysts based on ZSM-5, USY, and Mordenite zeolites has been prepared by the ionic exchange method. The NiZeol catalysts have been characterized by XRD and BET. The exchange levels and nickel contents of the catalysts have been determined by chemical analysis. The acidity of the zeolite supports has been investigated using NH3 adsorption microcalorimetry. The number of acidic sites was found to decrease according to the following sequence: HUSY > HZSM-5 > HMOR. The temperature programmed reduction studies showed that the most reducible catalyst is NiZSM-5. The Ni-exchanged zeolites presented good catalytic performance in the methane reforming by CO2. At a temperature of 650°C , CH4 conversions of 71 and 54% were achieved on NiUSY and NiZSM-5 respectively. At 400°C, CO2 FTIR adsorption has shown that CO2 decomposes into CO and oxygen on NiZSM-5 which explains its reactivity at such a low temperature, while no decomposition of this probe molecule was observed on the NiUSY catalyst. The catalytic performance was found to vary in the following sequence at 650°C: NiUSY > NiZSM-5 > NiMOR. Moreover, the catalytic performances were found to depend strongly on the CO2 /CH4 ratio in the feed and were markedly improved for CO2/CH4 greater than 1.
D. Halliche, O. Cherifi, Y. B. Taarit, A. Auroux, Kinetics and Catalysis, 2008, Vol. 49, No. 5, pp. 667–675

B2737 – Adsorption Equilibrium of Light Mercaptans on Faujasites

Both thermogravimetry and manometry coupled to calorimetry techniques were used to determine the adsorption equilibrium of ethyl mercaptan in pure and extruded NaX zeolites. Sorption isotherms were investigated from 298 to 373 K, and over a large range of pressure from 10?4 to 100 hPa. Adsorption heats were measured at 298 K. Reversible adsorption-desorption isotherms are type I shaped and characterize a very high adsorption affinity of NaX zeolites for ethylmercaptan. The sulfur compound entirely probes NaX zeolite ?-cages at micropore saturation. The presence of the mineral binder for the extruded zeolite does not affect the adsorption phenomenon. Adsorption data were well fitted using the Polanyi-Dubinin model. Calorimetric and isosteric heats do not change very much with loading, indicating that NaX zeolite is energetically homogeneous for the adsorption of ethyl mercaptan. Additional information concerning state of adsorbed phase were obtained from isosteric molar entropy curves. Therefore, the NaX faujasite appeared as a powerful potential candidate for industrial desulfurization of natural gas by adsorption process.
Guy Weber, Jean-Pierre Bellat, Frederic Benoit, Christian Paulin, Sophie Limborg-Noetinger, Michel Thomas, Adsorption 11, 183–188 (2005)

B2736 – Acid-base properties of alumina-supported M2O3 (Mÿÿ B, Ga, In) catalysts

The acid-base properties of -Al2O3 and alumina-supported B2O3, Ga2O3 and In2O3 have been determined by microcalorimetry of ammonia and sulfur dioxide adsorption. From the adsorption of NH3, it was found that the addition of B2O3 on alumina leads to an increase of the number of acid sites, while Ga2O3 and In2O3 additives caused a decrease in the acidity of alumina. Using SO2 as a probe molecule to study the basicity, the number of surface basic sites on alumina was found to be strongly decreased by the addition of boron oxide, while it was only slightly affected by the addition of gallium oxide and decreased by the addition of indium oxide. The differential heats of adsorption are discussed as a function of the coverage by the probe molecules. The electronic properties of the oxides are examined in order to explain the acid-base properties of the supported oxides.
A.L. Petre, J.A. Perdigon-Melon, A. Gervasini, A. Auroux, Topics in Catalysis Vol. 19, Nos. 3–4, May 2002

B2735 – The nature of the internal acid solution in sulfonated poly(styrene-co-divinylbenzene) resins

The acidities of a series of fully hydrated sulfonated poly(styrene-co-divinylbenzene) resins with varying levels of sulfonation from 0.80 to 5.25 mequiv g-1 have been characterized. Enthalpies of neutralization with aqueous NaOH have been measured by titration calorimetry. The degrees of acid dissociation ( ) have been measured using FT-Raman spectroscopy, based on the intensity of the –SO3- stretching band at 1033 cm-1. The same measurements have been made on aqueous solutions of p-toluenesulfonic acid ( p-TsOH), on the basis that these solutions are analogs of the internal solutions in the hydrated resin gels. For resins with low levels of sulfonation, and therefore relatively dilute internal acid solutions, the internal and the equivalent p-TsOH solutions are similar. However, significant differences are seen in highly sulfonated resins where the internal solution concentration is above 4.0 mol kg-1. At these concentrations, p-TsOH solutions show essentially complete dissociation and enthalpies of neutralization typical of a strong, fully dissociated acid in aqueous solution. In contrast, the acid groups in hydrated resins are largely undissociated and exhibit numerically higher enthalpies of neutralization, and catalytic activity measurements indicate that these acid groups are stronger than normal. It is proposed that this acidity enhancement is associated with networks of sulfonic acid groups which form in highly sulfonated resins. Although such networks have been previously proposed in dehydrated resins, this paper reports the first evidence for their existence in resins under conditions of full hydration.
S. Koujout, B.M. Kiernan, D.R. Brown, H.G.M. Edwards, J.A. Dale, S. Plant, Catalysis Letters Vol. 85, Nos. 1–2, January 2003

B2734 – The influence of solvent on the acidity and activity of supported sulfonic acid catalysts

The acid strengths and catalytic activities of sulfonic acids supported on polystyrene resins and ordered mesoporous HMS and SBA-15 silicas are compared. Acid strengths are measured by acid–base titration calorimetry in terms of the molar enthalpies of neutralisation with either NaOH or n-butylamine in water, acetonitrile and cyclohexane. Catalytic activities (turnover numbers) are reported in model reactions in water, 1,2-dichlorobenzene and anisole, and compared with acid strengths. In water, sulfonated resins are both stronger acids and more active catalysts than sulfonated silicas. Catalytic activities in water correlate well with these measured acid strengths. In acetonitrile the order of acid strengths is reversed and the sulfonated silicas are the stronger acids. Catalytic measurements in 1,2-dichlorobenzene, a similar dipolar aprotic solvent, show the same reversed order of activities. In the non-polar solvent cyclohexane (where only macroporous sulfonated resins show measurable acidity) the sulfonated silicas are again the stronger acids but by a larger margin. Catalytic activities in anisole, which is also only very weakly solvating towards sulfonic acid groups, show a similar trend. The results illustrate the role of the solvent in controlling the acid strength of solid acid catalysts, and the importance of taking this into account when designing acid catalysts for liquid phase processes.
S. Koujout, D.R. Brown, Catalysis Letters Vol. 98, No. 4, December 2004

B2733 – Microcalorimetric and FTIR Study of the Adsorption of Carbon Dioxide on Alkali-Metal Exchanged FER Zeolites

Adsorption of CO2 on alkali-metal exchanged (Li?, Na?, K?) FER zeolites was investigated by means of microcalorimetry and FTIR spectroscopy. The adsorption enthalpies strongly depend on coverage for all investigated materials and they are also influenced by concentration of Al in the framework. Especially, samples of Na- and K-FER with lower Si/Al ratio (8.6) exhibited substantially larger initial interaction energy than samples with Si/Al 27.5. Differences in zero-coverage adsorption energy of zeolites with different cation concentration (Si/Al ratio) are 9 and 7.2 kJ/mol for Na- and K-FER zeolites respectively. This phenomenon is attributed to formation of bridged CO2 adsorption complexes formed between two cations, which are characterized by IR absorption band of m3 stretching vibration mode at 2370 and 2357 cm-1 for Na- and K-FER respectively.
Roman Bulanek, Karel Frolich, Eva Frydova,,Pavel Cicmanec, Top Catal (2010) 53,1349–1360

B2731 – Catalytic Performance of Activated Carbon Supported Tungsten Carbide for Hydrazine Decomposition

Activated carbon (AC) supported tungsten carbide was reported for the catalytic decomposition of hydrazine for the first time. It was found that the WCx/AC- H catalyst prepared by a carbothermal hydrogen reduction process exhibited excellent catalytic performances both in the microreactor and in a 1 Newton hydrazine microthruster. The XRD, TEM and microcalorimetry results suggest that the formation of well crystallized W2C phase, the restraining of the carbon deposition, as well as the prohibiting of the methanation should be responsible for the high activity and stability of the WCx/AC-H catalyst in the hydrazine decomposition reaction.
Jun Sun, Mingyuan Zheng, Xiaodong Wang, Aiqin Wang, Ruihua Cheng, Tao Li, Tao Zhang, Catal Lett (2008) 123,150–155

B2727 – Microcalorimetric, infrared spectroscopic and DFT studies of ethylene adsorption on Ru, Ru/Sn and Ru/Cu catalysts

Microcalorimetric measurements of the adsorption of H2, CO and C2H4 were conducted on silica-supported Ru, Ru/Sn, Ru/Cu and Cu catalysts; infrared spectroscopic measurements were made of adsorbed CO and C2H4. The adsorption of C2H4 leads to formation of di-¾-adsorbed ethylene and ethylidyne species on Ru/SiO2 at 300 K, with an initial heat of 160 kJ/mol. Ethylene adsorption at 203 K leads to the formation of di-¾-adsorbed ethylene, ethylidyne species and weakly adsorbed ¼-bonded ethylene. The initial heats are 110, 95 and 75 kJ/mol on Ru/SiO2, 5Ru/Sn/SiO2 and Ru/Cu/SiO2, respectively. Lower heats of CO and C2H4 adsorption are measured on Ru/Cu/SiO2, primarily as a result of these adsorbates binding on both Cu and Ru. Quantum chemical calculations employing density functional theory were performed using (0001) slabs of Ru and Ru/Sn. The results of these calculations indicate that Sn weakens the interaction of ¼-bonded ethylene, di-¾-bonded ethylene and ethylidyne species with Ru by 41, 23 and 15 kJ/mol, respectively. This behavior is in contrast to the effect of adding Sn to Pt and Pd, for which Sn preferentially weakens the bonding of ethylidyne species to the surface.
Josephine M. Hill, Rafael Alcala, Ramchandra M. Watwe, Jianyi Shen, James A. Dumesic, Catalysis Letters 68 (2000) 129–138

B2726 – Activation of Amberlyst-70 for Alkene Oligomerization in Hydrophobic Media

We have observed that pretreating Amberlyst-70 with a C9 ketone improves, up to five times, the rate of alkene oligomerization. Physical characterization of Amberlyst-70 reveals minimal changes to the particle dimensions upon exposure to 5-nonanone. Diffuse reflectance infrared spectroscopy indicates an interaction between the ketone and the acid sites within the catalyst. While the total number of acid sites is similar before and after treatment with nonanone, microcalorimetric studies of butene adsorption and temperature programmed desorption studies of butene desorption reveal that both adsorption and desorption of butene occur more rapidly in the catalyst treated with 5-nonanone, indicating that pretreatment of the catalyst with the ketone decreases the barrier for butene transport by 5–6 kJ/mol. The peak temperature for TPD spectra of butene desorption are observed to shift from 360 K for nonanone-treated Amberlyst-70 to 376 K in the case of untreated sample. The catalytic effect of the treatment with nonanone decreases slowly with time-on-stream, but remains after 200 h on stream (with the rate still being a factor of 2 higher than for the untreated sample); however, catalytic activity can be recovered upon additional treatment with ketone.
David Martin Alonso, Jesse Q. Bond,,Dong Wang, James A. Dumesic, Top Catal (2011) 54, 447–457

B2725 – Gas/surface titration microcalorimetry. Energetics of oxygen adsorption on supported iridium catalysts

Measurements of the heat of adsorption of hydrogen on Ir/Al2O3 catalysts of different metal particle size were made by employing adsorption microcalorimetry. The values of this quantity were different for each sample and the results also indicated the heterogeneity of the iridium surface. In contrast to this, the heat of adsorption of oxygen measured on the same samples in the same manner was practically the same for all of them. The heat of oxygen adsorption as presented in the differential calorimetric isotherms was constant up to half the monolayer coverage for all the samples. This result is unexpected and in contradiction to the presence of surface heterogeneity in the iridium crystallites, as revealed by hydrogen adsorption. To clarify these anomalies the energetics of oxygen adsorption was determined using a different method. Titration experiments with hydrogen of preadsorbed oxygen were carried out. The heat of adsorption of oxygen was calculated from these results by means of adopting a thermochemical cycle. The values of heat of adsorption obtained as a function of the amount adsorbed unveiled the heterogeneity of the iridium surface. The differences found between the samples can be correlated to both the different particle size and degree of sintering of the samples
Jose M. Guil, Josefa E. Herrero Garc?a, Anselmo Ruiz Paniego, Jose M. Trejo Menayo, Topics in Catalysis Vol. 19, Nos. 3–4, May 2002

B2724 – Microcalorimetric, reaction kinetics and DFT studies of Pt–Zn/X-zeolite for isobutane dehydrogenation

Microcalorimetric measurements of the adsorption of H2 and C2H4 were carried out at 300 K on a Pt–Zn/X-zeolite catalyst (Pt : Zn atomic ratio equal to 1 : 1). The initial heats of H2 and C2H4 adsorption were equal to 75 and 122 kJ/mol, respectively, and these values are weaker than the values of 90 and 155 kJ/mol typically observed for supported Pt catalysts. Reaction kinetics measurements for isobutane dehydrogenation over the Pt–Zn/X-zeolite catalyst were carried out at temperatures from 673 to 773 K, at isobutane pressures from 0.01 to 0.04 atm, and at hydrogen pressures from 0.1 to 0.7 atm. The catalyst shows high activity and selectivity for dehydrogenation of isobutane to isobutylene. The reaction kinetics can be described with a Horiuti–Polanyi reaction scheme. DFT calculations were carried out for the adsorption of ethylene on slabs of Pt(111), Pt3Zn(111) and PtZn(011). Results from these calculations indicate that addition of Zn to Pt weakens the binding energies of ?-bonded ethylene, di-?-bonded ethylene, and ethylidyne species on atop, bridged, and three-fold Pt sites, respectively. These effects are most significant for the bonding of ethylidyne species, and they are least significant for ?-bonded ethylene species. Results from DFT calculations for the adsorption of formaldehyde show that addition of Zn to Pt weakens the di-?-bonding at Pt–Pt sites; however, this weakening effect of Zn on formaldehyde adsorption is less significant than the effect on ethylene adsorption. Moreover, the preferred location for adsorption of formaldehyde on PtZn(011) is a Pt–Zn site, whereas the preferred location for adsorption of ethylene is a Pt–Pt site. Thus, formaldehyde is adsorbed more strongly by 53 kJ/mol on PtZn(011) compared to the di-?-adsorption of ethylene, whereas formaldehyde and ethylene adsorb in the di-?-forms with comparable energies on Pt(111). This preferred adsorption of formaldehyde compared to ethylene on PtZn(011) may be at least partially responsible for the enhanced selectivity of Pt–Zn-based catalysts for hydrogenation of C=O groups compared to C=C bonds in ?,?-unsaturated aldehydes.
Joaquin Silvestre-Albero, Marco A. Sanchez-Castillo, Rong He, Antonio Sepúlveda-Escribano, Francisco Rodríguez-Reinoso, J.A. Dumesic, Catalysis Letters Vol. 74, No. 1–2, 2001

B2668 – Mesoporous silica synthesis: Energetics of interaction between framework and structure directing agent

The thermodynamics of mesoporous silicas (MCM-41, MCM-48, SBA-15, and SBA-16) were studied by solution calorimetry at 323 K in 25% aqueous HF. The enthalpies of formation were determined for calcined mesoporous silica (MS) and organic structure-directing agent (SDA) occluded samples (SDA: n-hexadeciltrimethylammonium bromide or CTAB, Pluronic P123, and Pluronic F127). The following are the measured interaction enthalpies between the MS and SDA: MCM-41/CTAB, ÿ6.1 kJ/mol SiO2; MCM-48/CTAB, ÿ12.3 kJ/mol SiO2; SBA-15/P123, ÿ19.7 kJ/mol SiO2; SBA-16/F127, ÿ19.9 kJ/mol SiO2. Per unit surface area, these interactions are ÿ0.08, ÿ0.15, ÿ0.43, and ÿ0.40 J/m2, respectively. Though these SDA–frame- work interaction energies are still small in magnitude, they are somewhat more exothermic than those in silica zeolite formation, reflecting the greater metastability of the MS materials and the role of the long chain SDA in stabilizing and space-filling the large pores. The cubic MS (SBA) show stronger SDA interactions than the hexagonal (MCM). The interaction energies confirm a complex landscape of many competing structures of similar energy; with the role of SDA kinetic in selecting a specific structure rather than energetic in strongly stabilizing a given state, as has already been noted for zeolites. The enthalpies of the calcined MS relative to quartz determined by HF solution calorimetry in this study are in excellent agreement with those determined previously by high temperature oxide melt solution calorimetry.
Olga Trofymluk, Andrey A. Levchenko, Alexandra Navrotsky, Microporous and Mesoporous Materials 149 (2012) 119–125

B2667 – Physical characterization of activated carbons with narrow microporosity by nitrogen (77.4 K), carbon dioxide (273 K) and argon (87.3 K) adsorption in combination with immersion calorimetry

In order to get more insight into the characterization of nanoporous carbons by gas adsorption, the use of different probe molecules has been compared. A series of activated carbons with ranging porosity (burn-off) have been prepared from olive stones using CO2 as activating agent and characterized using nitrogen and argon adsorption at low temperature (77.4 K for N2 and 87.3 K for Ar) together with CO2 adsorption at 273 K and immersion calorimetry into liquids of different molecular dimensions. Experimental results show that argon adsorption in narrow carbon micropores takes place at a higher relative pressure compared to nitrogen due to a weaker effective adsorption potential (lower strength of dis- persion forces), including the absence of specific interactions of argon with the adsorbent surface.We show further that application of advanced theoretical approaches based on the density functional theory (NLDFT and QSDFT) provides an accurate description of the pore-size distribution (PSD). The PSD obtained from the argon adsorption data at 87.3 K is in good agreement with immersion calorimetry measurements. Our results demonstrate that argon adsorption at 87.3 K in combination with the application of advanced DFT methods (e.g. QSDFT) allows for a reliable characterization of the narrow microporosity in highly heterogeneous activated carbons.
J. Silvestre-Albero, A. Silvestre-Albero, F. Rodr?guez-Reinoso, M. Thommes, Carbon 50 (2012) 3128-3133

B2656 – Study of adsorption sites heterogeneity in zeolites by means of coupled microcalorimetry with volumetry

Adsorption of CO2 as probe molecule on alkalimetal zeolites of MFI structure was investigated by joint volumetry–calorimetry. Consideration was given to the interpretation of the heat evolved when a probe molecule is adsorbed on the surface. In particular, the number and the strength of adsorption sites are discussed as functions of zeolite structure, concentration, and nature of extraframework cation. The adsorption heats (qiso) of CO2 interaction with alkali-metal cations decrease for MFI zeolite with high Si/Al in the sequence Li+>Na+>K+ from 54 kJ/mol to 49 and 43 kJ/mol, respectively. In addition, the adsorption heats are influenced by concentration of Al in the framework. This phenomenon is attributed to formation of bridged CO2 adsorption complexes formed between two cations. On the base of quantitative analysis of adsorption processes, presence of geminal adsorption complexes was suggested for adsorption at higher equilibrium pressures.
Roman Bulanek, Karel Frolich, Eva Frydova,,Pavel Cicmanec

B2655 – Thermodynamics of CO probe molecule adsorption on Cu–FER-zeolite comparison of TPD, FTIR, and microcalorimetry results

The existence of the new type of the adsorption complexes of carbon monoxide, where CO molecule interacts simultaneously with both copper and potassium cation, formed on so-called heterogeneous dual adsorption sites was detected by the FTIR spectroscopy and temperature programmed desorption technique (TPD) in the Cu, K–FER zeolite samples. The time-resolved IR spectroscopy and TPD experiments also proved their lower stability in the comparison with the classical monodentate adsorption complexes. The TPD curves of these materials exhibited low temperature desorption peak which was ascribed to these sites. The energetic parameters (i.e., energy and entropy of adsorption) as well as distribution of all present Cu? sites were obtained by the fitting of TPD data to the phenomenological model. Obtained results suggest that the heterogeneous dual sites are special form of the adsorption sites localized on the wall of channels destabilized due to significantly higher change of the entropy of adsorption. Direct microcalorimetric measurement proved energetic equality of single and heterogeneous dual sites together with the validity of the adsorption energy values obtained from TPD.
Pavel Cicmanec, Roman Bulanek, Karel Frolich, J Therm Anal Calorim (2011) 105, 837–844

B2647 – Thermochemistry of proton containing borosilicate, aluminosilicate and gallosilicate zeolite beta

The thermochemistry of proton containing borosilicate, aluminosilicate and gallosilicate zeolites with beta topology (B-BEA, Al-BEA and Ga-BEA) is described. Thermogravimetry and differential scanning calorimetry on these materials indicate the substitution of Al by Ga or B in the beta framework reduces the decomposition temperature. Water adsorption calorimetry directly measured the hydration enthalpies of these samples. B-BEA and Ga-BEA have less exothermic hydration enthalpies than Al-BEA. High temperature oxide melt solution calorimetry was performed to derive the formation enthalpies of hydrated samples (8.9–18.8 kJ/mol relative to oxides on TO2 molar basis). The formation enthalpies of dehydrated phases (33.2–55.1 kJ/mol relative to oxides on TO2 molar basis) were calculated from the formation enthalpies of hydrated phases and the hydration enthalpy.
Wei Zhou, Pingping Sun, Peng Zhang, Alexandra Navrotsky, Microporous and Mesoporous Materials, 142 (2011) 749–753

B2645 – n-Butane adsorption on Cu3(btc)2 and MIL-101

The n-butane adsorption capacity and heat of adsorption for the metal–organic frameworks Cu3(btc)2 (btc = benzene-1,3,5-tricarboxylate) and MIL-101 was determined at three different temperatures (293, 303, and 313 K) under dynamic conditions at atmospheric pressure with a micro-balance combined with a Tian-Calvet micro-calorimeter. The adsorption rate was studied at the adsorption temperature of 293 K. The n-butane adsorption properties were compared with activated carbon Sorbonorit 3. For low n-butane concentration the microporous Cu3(btc)2 has a higher storage capacity than the mesoporous material MIL-101. For high n-butane concentrations it is vice versa. The saturation capacity at 293 K for Cu3(btc)2 is 3.7 mmol g?1 and for MIL-101 remarkable 11.2 mmol g?1. The storage capacity and adsorption rate depends on the alkane concentration. For higher n-butane concentration MIL-101 has a higher adsorption rate than Cu3(btc)2 independent on the amount of adsorbed n-butane
Nicole Klein, Antje Henschel, Stefan Kaskel, Microporous and Mesoporous Materials, 129 (2010) 238–242

B2586 – Enthalpy–entropy compensation for n-hexane adsorption on HZSM-5 containing transition metal ions

In this work, the values of entropy changes related to n-hexane adsorption onto ion-exchanged ZSM-5 zeolites were calculated from differential heats, obtained from microcalorimetric experiments. The existence of enthalpy–entropy compensation effect, evidenced by the linearity of ÿDH vs. ÿDS plots and characteristic for all investigated ZSM-5 zeolites, was found. In the case of ZSM-5 structure, modifying the zeolite structure by ion-exchange gives rise to changes in the heats of adsorption and adsorption entropy in the same manner. The factors that can influence the appearance of entropy–enthalpy compensation were discussed. It was found that compensation effect is governed by ion-induced dipole interaction between highly polarizing cationic centres in zeolite and nonopolar n-hexane molecules, and hence, depends on the size, charge and electron configuration of the cation. It was found also that the compensation temperature is in correlation with the number of zeolites’ strong acid centres. Contrary to the adsorption of n-hexane on ZSM-5 zeolites, compensation effect was not found for the adsorption of the same gas on faujasite-type zeolites.
R. Hercigonja, V. Rac, V. Rakic, A. Auroux, J. Chem. Thermodynamics 48 (2012) 112–117

B2585 – Selective oxidation of gas phase ammonia over copper chromites catalysts prepared by the sol–gel process

Selective gas phase oxidation of ammonia at atmospheric pressure was studied over a series of undoped and doped (Mn, Ag) copper chromites prepared by sol–gel process (SG). The catalysts were characterized by elemental analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and by adsorption microcalorimetry (AMC). A comparative study was made with a commercial copper chromite catalyst. The surface of the sol–gel undoped catalyst was found to be enriched in high valence chromium species with respect to the commercial one (Cr6+/Cr3+=0.56 versus 0.39 for commercial catalyst). From XPS, the Cu2+/(Cu°+Cu+) ratio was the same (ca. 5) in both catalysts but the sol–gel sample, contained twicemore surface copper species (8.3 at.%) than the commercial one (17.6 at.%). Ammonia AMC experiments showed both a higher ammonia uptake and a wider strength distribution of adsorption sites on the sol–gel-prepared sample than on the commercial one. Improved catalytic performance in selective oxidation of ammonia at low temperature was obtained by simultaneous addition of silver and manganese to the sol–gel-prepared copper chromite.
A. Kaddouri, N. Dupont, P. Gélin, A. Auroux, Catalysis Communications 15 (2011) 32–36

B2584 – Acid–base properties of niobiumzirconium mixed oxide catalysts for glycerol dehydration by calorimetric and catalytic investigation

The acid–base properties of fresh and used niobiumzirconium mixed oxide catalysts, used for the dehydration of glycerol to acrolein, have been characterized by various techniques. These techniques include ammonia thermoprogrammed desorption (TPD), infrared spectroscopy of absorbed pyridine, and adsorption microcalorimetry of ammonia and sulfur dioxide. Relationships between the catalytic properties and the acid–base properties of fresh catalysts have been investigated. The most efficient catalysts were shown to be those for which the zirconia support had a better niobium oxide species covering, but no specific relationship could be established between the acid–base, and the selectivity to acrolein. Characterization of the used catalysts showed that the acidic properties of the catalysts had changed considerably with the time spent on stream. No further strong acid sites, and only weak or very weak acid sites were detected. A linear relationship between the total quantity of remaining acidic sites and the rate of glycerol conversion was determined, taking into account an intrinsic activity of the stronger sites, which is more than ten times that of the weaker ones. The deactivation of the catalysts as a function of time on stream has been related to the formation of cyclic molecules, produced by the reaction of acrolein with byproducts resulting from the decomposition of hydroxyacetone and also possibly acrolein and glycerol.
P. LauriolGarbey, G. Postole, S. Loridant, A. Auroux, V. Belliere-Baca, P. Rey, J.M.M. Millet, Applied Catalysis B: Environmental 106 (2011) 94– 102

B2582 – Influence of surface acid–base properties of zirconia and titania based catalysts on the product selectivity in gas phase dehydration of glycerol

Acid–base properties of zirconia and titania basedmaterialswere investigated by adsorption microcalorimetry of NH3 and SO2 probemolecules. Catalytic performance of the catalystswas also tested in the gas phase dehydration of glycerol with the intention of finding correlations between catalytic activity and surface acid–base features. Results show that the number of basic sites directly affects the selectivity in gas phase dehydration of glycerol to produce acrolein. Therefore, in order to realize the target reaction it is necessary to control not only the strength and the amount of the desired sites (acidic ones), but also to hinder as much as possible the number/strength/action of the undesired ones (basic ones).
Dušan Stoši?, Simona Bennici, Jean-Luc Couturier, Jean-Luc Dubois, Aline Auroux, Catalysis Communications 17 (2012) 23–28

B2581 – CeO2–Nb2O5 mixed oxide catalysts: Preparation, characterization and catalytic activity in fructose dehydration reaction

In this work, ceria–niobia mixed oxides have been prepared by coprecipitation. The structural, textural, and surface properties of these materials have been fully characterized using appropriate techniques (lowtemperature adsorption–desorption of nitrogen, thermogravimetric analysis, Xray diffraction analysis (XRD), Xray photoelectron spectroscopy (XPS), Raman spectroscopy and temperatureprogrammed reduction/oxidation (TPR/O)). The acid–base properties were estimated by the adsorption of appropriate probe molecules – NH3 or SO2 were used to estimate the population, strength and strength distribution of acid or basic sites, by means of adsorption microcalorimetry. The nature of acidic sites was determined through the adsorption/desorption of pyridine, studied by infrared spectroscopy. New phases between the oxides were not formed, while there is evidence of interaction between them, as revealed by XRD and Raman spectroscopy. All investigated mixed oxide samples are amphoteric and possess redox centers on their surface. Both redox and acid–base properties are dependent on the ratio of ceria to niobia in the samples. Both Lewis and Brönsted acid sites are present on the surface of the mixed oxides. In order to check catalytic abilities of these materials, reaction of fructose dehydration has been performed. All the investigated materials are catalytically active in fructose dehydration; conversion of fructose and selectivity to 5hydroxymethylfurfural (5HMF) improved with increasing content of niobia in the samples.
Dusan Stosic, Simona Bennici, Vesna Rakic, Aline Auroux, Catalysis Today (2011)

B2579 – Investigation of the WO3/ZrO2 surface acidic properties for the aqueous hydrolysis of cellobiose

A series of WOx/ZrO2 with various tungsten oxide loadings (1–20) wt.% was prepared by co-precipitation. The catalysts were characterized by XRD, BET, XPS, Raman spectroscopy, TPR, ammonia adsorption microcalorimetry and pyridine FT-IR spectroscopy. XRD and Raman results showed that the ZrO2 support is predominantly present in the monoclinic phase when the WO3 loading was less than 5 wt.% and predominantly in the tetragonal phase above 10 wt.%. No formation of bulk WO3 was detected for the catalysts calcined at 700 °C, which is also the case for the highest loaded samples. TPR results revealed that isolated WO3 species are easier to reduce than amorphous WOx. The ammonia adsorption microcalorimetric study evidenced acid sites with adsorption heats in the range 90bQdiffb130 kJ.mol?1, in amounts which increase with increasing WO3 loading until reaching the monolayer. Concerning the acid site nature, a progressive increase of the amount of Brønsted sites with the WO3 loading was observed. The catalytic reaction of cellobiose disaccharide hydrolysis showed a better catalytic performance on the highest WO3 loaded catalysts, associated to the presence of Zr-stabilized WOx clusters and a strong protonic acidity.
R. Kourieh, S. Bennici, M. Marzo, A. Gervasini, A. Auroux, Catalysis Communications 19 (2012) 119–126

B2553 – Relationship between adsorption properties of Pt–Cu/SiO2 catalysts and their catalytic performance for selective hydrodechlorination of 1,2-dichloroethane to ethylene

Microcalorimetric adsorption technique was employed to study the interaction of the reactants and product in the 1,2-dichloroethane hydrodechlorination over Pt/SiO2, Cu/SiO2 and Pt–Cu/SiO2 catalysts in order to understand the high selectivity towards C2H4 on the Pt/SiO2 catalyst modified by Cu. When the adsorption properties of the reactants and product on bimetallic catalysts were compared with those on monometallic counterparts, significant differences in the strength and number of adsorption sites concerning the reactants and product were evidenced. The adsorption properties of the bimetallic catalysts could be attributed to the change in Pt surface structure modified by Cu, studied by the microcalorimetry and FTIR of CO adsorption. Relating the adsorption properties with high ethylene selectivity on bimetallic catalysts, we inferred that high ethylene selectivity on bimetallic catalysts could be attributed to the moderate adsorption and activation of reactants and product. This work gave the direct evidence of high C2H4 selectivity in 1,2-dichloroethane hydrodechlorination reaction on the Pt–Cu/SiO2 catalysts from the energetic point of view.
Lin Li, Xiaodong Wang, Aiqin Wang, Jianyi Shen, Tao Zhang, Thermochimica Acta, 494 (2009) 99-103

B2497 – Calorimetric study of the reversibility of CO pollutant adsorption on high loaded Pt/carbon catalysts used in PEM fuel cells

A major obstacle to the broader use of fuel cells is the poisoning of supported Pt catalysts by the CO present in virtually all feeds. In this paper, the microcalorimetry technique was employed to study and compare the CO adsorption properties of different commercial carbon-supported platinum catalysts with high Pt loading, aimed to be used in proton exchange membrane fuel cells (PEMFCs) applications. Combined with other techniques of characterization, such as BET, XRD, TPD-MS and TPR, adsorption microcalorimetry has permitted a better understanding of the studied systems. The pore architecture of Pt/C catalysts was found to influence the kinetics of heat release during CO adsorption. The accessibility of CO molecules to the adsorption sites increased with the mesoporosity of the catalyst. The degree of catalyst poisoning by CO upon successive air/H2/CO cycles varied between 2 and 30% for the different studied samples. These results confirm that the surface chemistry of the catalyst, and in particular the Pt deposition method, affects the surface site energy distribution and consequently the adsorptive properties towards H2 and CO. It was found that both H2 and CO are chemisorbed on the investigated samples. Pt/C powders exhibit higher differential heats of carbon monoxide adsorption in comparison with hydrogen adsorption. A reaction between pre-adsorbed H2 and CO from the gas phase takes place on Pt/C catalysts as a result of competitive adsorption
Georgeta Postole, Simona Bennici, Aline Auroux, Applied Catalysis B: Environmental 92 (2009) 307–317

B2488 – Thermal analysis of sulphur impregnated activated carbons with mercury adsorbed from the vapour phase

Activated carbons (AC), particularly those containing sulphur, are effective adsorbents for mercury (Hg) vapour at elevated temperatures. Activated carbon-based technologies are expected to become a major part of the strategy for controlling mercury emission from coal-fired power plants. Understanding the mechanism of mercury adsorption on sulphur impregnated activated carbons (SIAC) is essential to optimizing activated carbons for better mercury removal efficiency and to developing technologies for the handling of the spent AC. In this work thermal analysis before and after mercury uptake was carried out for the SIAC prepared under various conditions from oil-sand petroleum coke using a simultaneous differential thermal analyzer. Samples were heated at 20°C min–1 under nitrogen in the temperature range from ambient to 1000°C. The DSC curves suggest both endothermic and exothermic changes during heating. The endothermic processes were attributed to evaporation of moisture and other volatile components. The exothermic processes existed in a wide temperature range of 150–850°C likely due to the oxidation reactions between carbon and adsorbed oxygen, oxygen-containing surface groups. The enthalpies of liquid mercury interaction with SIAC at different Hg/AC mass ratio were also measured at 30, 40 and 50°C using a differential scanning calorimeter. The combination of thermal analysis and calorimetry techniques enabled confirmation that the interaction of mercury with SIAC involves both physical and chemical processes
Irina V. Bylina, S. Tong, C. Q. Jia, Journal of Thermal Analysis and Calorimetry, Vol. 96 (2009) 1, 91–98

B2483 – Thermal hazard evaluation procedure for detoxifying system of hazardous gases by using of reaction calorimeter

The thermal behaviors of hazardous gas adsorbents were observed using a C80 calorimeter in order to develop a comprehensive thermal hazard evaluation procedure for a hazardous gas detoxifying system. Newly modified cells for the C80 were used to simultaneously monitor the pressure and the heat flow. The cells were also available for adsorbed gas switching. Adsorption/desorption experiments showed various thermal behaviors of the different gas-adsorbent combinations. The accidental incorporation of air into the cartridges proved to be a potential risk for heat generation. In addition, two kinds of experimental results in different states, static pressure and gas-circulation, were compared. As a result, the experimental apparatus used in this study exhibited the capability of evaluating the thermal hazards under the situation of accidental contamination by either air or other undesirable gases as well as normal adsorption.
K. Yuasa, M. Kumasaki, T. Mizutani, M. Arai, Journal of Thermal Analysis and Calorimetry, Vol. 93 (2008) 1, 41–45

B2479 – Knoevenagel condensation reaction over acid–base bifunctional nanocrystalline CexZr1-xO2 solid solutions

Highly thermally stable three-dimensional spongelike mesoporous CexZr1-xO2 solid solutions consisting of nanometer size particles with different Ce/Zr compositions were synthesized by a modified sol–gel procedure using a triethanolamine/water mixture as a solvent to be used in liquid Knoevenagel condensation reaction. These materials were investigated in detail by means of X-ray diffraction (XRD), Raman spectroscopy, chemical analysis, X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), UV–Vis spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and adsorption microcalorimetry. The XRD, HRTEM and XPS studies proved the presence of nanocrystalline CexZr1-xO2 solid solutions. These solid solutions showed excellent chemoselectivity in the classical Knoevenagel reaction. The large pore sizes (around 10 nm) highlight the possibility of using CexZr1-xO2 as a support material for versatile catalytic systems. The results obtained from NH3 and SO2 adsorption microcalorimetry experiments successfully demonstrated the incorporation of ZrO2 into the CeO2 lattice resulting in both acidic and basic surface sites in a mixed oxide matrix.
Georgeta Postole, Biswajit Chowdhury, Bikash Karmakar, Kumari Pinki, Julie Banerji, Aline Auroux

B2477 – The back titration of chemisorbed atmic oxygen on copper by carbon monoxide investigated by microcalorimetry and transient kinetics

The back-titration of atomic oxygen chemisorbed on metallic copper using carbon monoxide is investigated by microcalorimetry. Results from simulations based on a microkinetic model of the back-titration are used for processing of microcalorimetric data. In addition, surface oxidation of copper by nitrous oxide is investigated by microcalorimetry. The results are compared with results obtained by nitrous oxide reactive frontal chromatography and by static oxygen adsorption studied by microcalorimetry. The heat of adsorption of nitrous oxide on copper amounts to 304 kJ mol–1, and the heat of adsorption of carbon monoxide on surfaceoxidized copper is in the range from 120 to 70 kJ mol–1.
R. Naumann d’Alnoncourt, B. Graf, X. Xia, M. Muhler, Journal of Thermal Analysis and Calorimetry, Vol. 91 (2008) 1, 173–179

B2475 – Preparation and characterization of V-Ag-O catalysts for the selective oxidation of toluene

V-Ag-O complex oxide catalysts with relatively high surface areas of 13–21m2/g could be prepared by the heterogeneous azeotropic distillation (HAD) method. Specifically, V2O5 and AgNO3 were dissolved in aqueous solution of H2O2, followed by evaporation and drying in n-butanol at 353 K. Silver vanadates with highly dispersed nano silver particles in the layered structures of VOx might be formed during the preparation process, which were then turned into Ag0.68V2O5 and metallic silver during the reaction of selective oxidation of toluene at 573 K. Characterizations with microcalorimetric adsorption of NH3, temperature programmed reduction and isopropanol probe reactions showed that the V-Ag-O catalysts exhibited weaker surface acidity but stronger redox ability than the VOx, and therefore the better performance for the selective oxidation of toluene to benzaldehyde and benzoic acid. In addition, the V-Ag-O catalysts prepared by the HAD method exhibited much higher activity than its counterpart prepared by the co-precipitation for the conversion of isopropanol and the selective oxidation of toluene to benzaldehyde and benzoic acid in air.
Mingwei Xue, Hui Chen, Huiliang Zhang, Aline Auroux, Jianyi Shen, Applied Catalysis A: General 379 (2010) 7–14

B2474 – Surface and catalytic properties of V2O5–TiO2/SO4 2- catalysts for the oxidation of methanol prepared by various methods

The influence of the preparationmethod on the surface and catalytic properties of sulfated vanadia–titania catalysts has been studied. V2O5–TiO2/SO4 2? (VTiS) catalysts with 25 wt% V2O5 and 0.2–6.5 wt% S were prepared by co-precipitation, sol–gel and mechanical grinding methods and calcined at 723K in air. The structural properties were characterized by O2 chemisorption and laser Raman spectroscopy (LRS). The surface acidity was determined by the techniques of NH3 adsorption microcalorimetry and pyridine adsorption infrared spectroscopy (FT-IR). Catalytic tests of oxidation of methanol to dimethoxymethane (DMM)were performedat atmospheric pressure inafixed-bedmicro-reactor. TheRamanspectra revealed that vanadia existed in the form of a crystalline V2O5 phase. The results of ammonia adsorption of microcalorimetry showed a much lower heat of adsorption for samples with high content of SO4 2?. Meanwhile, pyridine adsorption of FT-IR showed that both Lewis and Brønsted acid sites were present on the surface of all VTiS catalysts. The catalytic performance was also influenced by the preparation methods. VTiS-CP catalyst, prepared by co-precipitation, exhibited the highest DMM yield with a DMM selectivity of 86% for 61% methanol conversion at 423 K
H. Zhao, S. Bennici, J. Shen, A. Auroux, Journal of Molecular Catalysis A: Chemical 309 (2009) 28–34

B2473 – Effect of vanadia loading on the acidic, redox and catalytic properties of V2O5–TiO2 and V2O5–TiO2/SO4 2- catalysts for partial oxidation of methanol

V2O5/TiO2 and V2O5/TiO2–SO4 2- catalysts with various vanadia loadings (5, 15 and 25 wt% V2O5) were prepared by successive incipient wetness impregnations and the effect of doping with SO4 2- was studied. The catalysts were characterized by XRD, BET, XPS, Raman spectroscopy, redox cycles (TPR1/TPO/TPR2), ammonia adsorption microcalorimetry and tested in the selective oxidation of methanol to dimethoxymethane (DMM). The Raman spectra revealed the formation of crystalline V2O5 particles when the vanadia coverage was higher than 15 wt%. Redox cycles revealed that the monomeric vanadia species were easier to reduce butmore difficult to oxidize than the polymeric and crystalline species. The supported vanadia species were found to be composed of stoichiometric V2O4 and V2O5, as shown by XPS. The ammonia adsorption microcalorimetric study evidenced acid sites with adsorption heats Qdiff > 110 kJ mol 1, in amounts which increased upon the addition of SO4 2- but decreased with increasing vanadia loading. Furthermore, the results of the methanol oxidation reaction suggest that the addition of SO4 2- on highly dispersed supported vanadia catalysts promoted the catalytic activity.
H. Zhao, S. Bennici, J. Cai, J. Shen, A. Auroux, Catalysis Today 152 (2010) 70–77

B2472 – Influence of the host oxide of sulfated-titania catalysts on partial oxidation methanol reaction

A series of sulfated binary titania-based (MxOy–TiO2–SO4 2?, Mx = Cr, Mn, Fe, Co or Mo) catalysts were prepared by co-precipitation and tested for partial oxidation of methanol. The structural properties were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The acidic and redox properties were examined using ammonia adsorption calorimetry and temperature-programmed reduction coupled with mass spectrometry (TPR–MS) techniques, respectively. The surface Mx species were essentially 100% dispersed on catalysts, as confirmed by XRD and Raman spectroscopy characterization. XPS results indicated the oxidation state of surfaceMx species. In addition, Ti and S species were present in their fully oxidized states for all the samples. The results of ammonia adsorption calorimetry showed a surface reaction between chromium oxide and ammonia. The addition of MxOy host oxide not only enhanced the redox properties of sample TiS but also brought changes in the sulfate reduction process, as investigated by TPR–MS. The best catalytic performance was obtained for sampleMoO3–TiO2–SO4 2? with high activity. Furthermore, the distribution of reaction products was examined to provide information about the surface acidity and redox properties simultaneously.
Hongying Zhao, Simona Bennici, Jianyi Shen, Aline Auroux, Applied Catalysis A: General 385 (2010) 224–231

B2471 – Acidic and adsorptive properties of SBA-15 modified by aluminum incorporation

In this work, Al-SBA-15 samples with different Si/Al ratios were synthesized; Al was incorporated in the mesoporous SBA-15 structure either using the direct synthesis method, with tri-block copolymer P123 as surfactant, or by the post-synthesis method. The porous solids were characterized using different techniques, such as: XRD, pore size distribution, 27Al MAS NMR, and XPS. Acidic properties were estimated by adsorption and titration microcalorimetry, respectively. Ammonia and pyridine were used as probe molecules in the first case, while aniline in n-decane was used in the second one. FT-IR of pyridine adsorption and XPS of ammonia adsorption completed the characterization of acid properties. The increase of acidity with the incorporation of aluminum was evidenced; lower Si/Al ratios led to higher acidity of the sample. Microcalorimetry was also used to test the adsorption properties of these mesoporous materials toward pollutants such as methyl ethyl ketone, propionaldehyde and acetonitrile (in gas phase) and nicotine (in aqueous phase). The ketone was better retained in comparison to the other two molecules. Regarding nicotine, its adsorption was strongly influenced by the aluminum content in the solids; the higher the quantity of aluminum, the lower the adsorption of nicotine.
B. Dragoi, E. Dumitriu, C. Guimon, A. Auroux, Microporous and Mesoporous Materials 121 (2009) 7–17

B2470 – Calorimetric study of the acidic character of V2O5–TiO2/SO4 2- catalysts used in methanol oxidation to dimethoxymethane

The surface acidic properties of sulfated vanadia–titania catalysts prepared by various methods were investigated by adsorption microcalorimetry, using ammonia as probe molecule. The acidic characteristics of the samples were shown to be strongly affected by the preparation method, calcination temperature, and sulfur content. The samples prepared by sol–gel and mechanical grinding exhibited higher acidity than co-precipitated samples. Moreover, increasing the calcination temperature of coprecipitated samples resulted in a decrease in surface area from 402 to 57 m2 g-1 and sulfur content from around 4 to 0.2 mass%, but up to a certain point generated a stronger acidity. The optimal calcination temperature appeared to be around 673 K.
H. Zhao, S. Bennici, J. Shen, A. Auroux, J Therm Anal Calorim (2010) 99:843–847

B2469 – Nature of surface sites of V2O5—TiO2/SO2- 4 catalysts and reactivity in selective oxidation of methanol to dimethoxymethane

The selective oxidation of methanol to dimethoxymethane (DMM) over sulfated vanadia–titania catalysts, prepared by co-precipitation and calcined at different temperatures, was studied in the 393–473 K interval under steady state conditions. The catalysts were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller isotherms (BET), inductively coupled plasma optical emission spectroscopy (ICP–OES), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. The redox and acidic properties were examined using temperature programmed reduction (TPR), isopropanol probe reaction, ammonia adsorption calorimetry, and pyridine adsorption FTIR techniques. As evidenced by pyridine adsorption FTIR, some Brönsted acid sites transformed to Lewis sites upon removal of sulfate species by washing the samples with deionized water. A high sulfur content increased the number of Brönsted acid sites but reduced their strength. The best catalyst revealed the presence of amorphous polymeric VOx species with terminal V@O bonds, and both redox and Brönsted acid sites, resulting from an adequate balance between the calcination temperature and the sulfate concentration. These are the key parameters for optimizing the DMM production.
Hongying Zhao, Simona Bennici, Jianyi Shen, Aline Auroux, Journal of Catalysis 272 (2010) 176–189

B2468 – Study of acidic commercial WOx/ZrO2 catalysts by adsorption microcalorimetry and thermal analysis techniques

In this work we report about the characterization of the acidic and redox properties of four different commercial tungstated zirconia catalysts with W loadings of about 12–13 mass%. The samples have been characterized in terms of their micro-structural and surface properties by BET, X-ray diffraction, temperature programmed reduction, elemental chemical analysis and adsorption microcalorimetry of NH3. Improved acidity has been detected upon addition of WO3 to zirconia and differences between the samples were pointed out thanks to the results obtained by the complementary physicochemical techniques used in this study.
R. Kourieh, S. Bennici, A. Auroux, J Therm Anal Calorim (2010) 99:849–853

B2426 – Equilibrium desorption isotherms of water, ethanol, ethyl acetate, and toluene on a sodium smectite clay

Desorption isotherms for water, ethanol, ethyl acetate and toluene from a sodium smectite clay have been determined by both dynamic vapor sorption (DVS) measurements and Knudsen thermogravimetry (KTGA), at the exception of toluene that was measured only by the DVS method. The results obtained using these two methods were in satisfactory agreement, providing reliable insight into the desorption process, with certain lack of precision for ethyl acetate. The observed desorption behaviour suggests a liquid like phase at high volatile load, and a sorbed state in which molecules interact with the counter ions, at low volatile contents. However, the isotherms for water determined at various temperatures nearly superposed when plotted as a function of water activity, indicating the strength of the interactions in the clay–water system to remain of the same order of magnitude as that in bulk water, consistent with previous ab initio calculations.
Pascal Clausen, Marco Signorelli, Andreas Schreiber,,Eric Hughes, Christopher J. G. Plummer, Dimitrios Fessas, Alberto Schiraldi, Jan-Anders E. Manson, J Therm Anal Calorim (2009) 98:833–841

B2423 – Adsorption of CO2 on Hydrotalcite-Derived Mixed Oxides: Sorption Mechanisms and Consequences for Adsorption Irreversibility

Magnesium-aluminum double oxides derived from the thermal treatment of layered hydroxides (hydrotalcites) have been tested for CO2 adsorption. The effects of various preparation parameters, such as the incorporated cation (K or Na), the mode of addition of magnesium and aluminum precursors, the presence of sonication, and the calcination temperature, on the adsorption capacity under mild conditions were studied using thermogravimetry and calorimetry. Calorimetric and FTIR data were used to explain the adsorption mechanisms leading to the undesirable irreversible adsorption. This adsorption was related to the formation of unidentate CO2-adsorbent species with the strongest adsorption sites, whereas bidentate and surface bicarbonates lead to highly reversible adsorption. In conclusion, preparation procedures that lead to an increase in the strength of basic sites do not lead to significant increases in the adsorption capacity, but rather lead to more difficult regeneration of the saturated support.
Marta Leon, Eva D?az, Simona Bennici, Aurelio Vega, Salvador Ordonez, Aline Auroux, Ind. Eng. Chem. Res. 2010, 49, 3663–3671

B2422 – Influence of the metal oxide support on the surface and catalytic properties of sulfated vanadia catalysts for selective oxidation of methanol

The selective oxidation of methanol to dimethoxymethane (DMM) was performed over a series of binary vanadia-based oxides (V2O5-TiO2, V2O5-ZrO2, V2O5-Al2O3 and V2O5-CeO2) and the corresponding sulfated catalysts. The physicochemical properties of catalysts were characterized by BET, Raman, XPS, TPR–MS, ammonia adsorption calorimetry and sulfate TPD–MS techniques. The strength of the sulfate-support interaction depends on the nature of the oxide support and increases in the following order CeO2 > Al2O3 > ZrO2 > TiO2. The catalytic reactivity was correlated with the nature of VAO-support bonds. Sample V2O5-TiO2 exhibits the highest intrinsic activity of methanol oxidation. With the addition of sulfate, the selectivity to DMM was enhanced whereas the turnover frequency (TOF) value of vanadium sites decreased, with a rate depending on the strength of sulfate-support bonds. The best catalyst (V2O5-TiO2-SO42-) with higher DMM yield presented higher reducibility, proper acidity and moderate strength of sulfate species.
Hongying Zhao, Simona Bennici, Jingxuan Cai, Jianyi Shen, Aline Auroux, Journal of Catalysis 274 (2010) 259–272

B2421 – Activated carbon porosity tailoring by cyclic sorption / decomposition of molecular oxygen

Activated-carbon pore size tailoring is usually achieved by pore size reduction, pore size widening or more rarely by direct activation. Successive widening cycles composed of an initial molecular oxygen sorption step, followed by a carbonization step under nitrogen, have been applied to three different materials in order to study their gradual pore size modifications. For years, the whole microporosity obtained after several cycles is known to present better pore size distribution than those inherited from conventional activations. Moreover, as shown in the present paper, the gradual obtained microporosities cover a wide and valuable range of porous textures highly dependent on the initial material origin and initial activation. Gradual mean pore size evolutions of 1 or 2 A° per cycle were observed linked to a simultaneous increase in microporous specific volume in the case of pitch-based and coconut activated carbons, respectively. Comparatively, the microporous specific volume of a commercial coconut carbon molecular sieve was increased by 26% without modification of its mean pore size and therefore of its sieving effect. Those results have been used to test a simple textural model of activated carbon porosity proposed in the recent literature.
X. Py, A. Guillot, B. Cagnon, Carbon 41 (2003) 1533–1543

B2416 – Adsorption of organic pollutants over microporous solids investigated by microcalorimetry techniques

This work is focused on the gas and liquid-phase adsorption of pollutants: propanol, 2-butanone, phenol and nicotine onto zeolites (H-BETA, H-ZSM-5, H-MCM-22, and clinoptilolite). Textural properties and origin of zeolites were taken into account as criteria of adsorbents selection. The aldehyde and the ketone were adsorbed in the gas phase using microcalorimetry linked to a volumetric line to evaluate adsorption. Adsorptions in water were carried out for phenol and nicotine and the evolved heats during adsorption were measured by a differential heat flow reaction calorimeter with stirring. Results are discussed in relation with the pore sizes and various interactions which could occur between the adsorbent and the adsorbate.
B. Dragoi, V. Rakic, E. Dumitriu, A. Auroux, J Therm Anal Calorim (2010) 99, 733–740

B2415 – The investigation of phenol removal from aqueous solutions by zeolites as solid adsorbents

This work reports results on phenol adsorption from aqueous solutions on synthetic BEA ( ) and MFI (ZSM-5) zeolites, studied by heat-flow microcalorimetry. For the sake of comparison, the adsorption was performed on activated carbon, a solid customarily used for removal of phenol from water. The obtained values of heats evolved during phenol adsorption indicate the heterogeneity of active sites present on the investigated systems for the adsorption of phenol. In addition, the amounts of adsorbed pollutant were determined and presented in the form of adsorption isotherms, which were interpreted using Langmuir, Freundlich, Dubinin–Astakov and Sips’ equations. The latter was found to express high level of agreement with experimental data. The results obtained in this work reveal that the adsorption of phenol on zeolites depends on both Si/Al ratio and on the pore size. Hydrophobic zeolites that possess higher contents of Si show higher affinities for phenol adsorption. Among investigated zeolites, zeolite possesses the highest capacity for adsorption of phenol. The possibility of regeneration of used adsorbents was investigated by thermal desorption technique. It has been shown that in the case of zeolite the majority of adsorbed phenol is easily released in the low temperature region.
Ljiljana Damjanovic, Vesna Rakic, Vladislav Rac, Dusan Stosic, Aline Auroux, Journal of Hazardous Materials 184 (2010) 477–484

B2414 – The adsorption of nicotine from aqueous solutions on different zeolite structures

The present work is focused on the adsorption of nicotine from aqueous solutions. Based on the data available in the literature, serious concern is claimed regarding the appearance of nicotine in ground, surface and municipal wastewaters. In order to investigate the possibility of abatement by adsorption, three different types of zeolites (BEA, MFI and HEU) have been applied as adsorbents. In addition, the adsorption was performed on activated carbon, a solid customarily used for removal of pollutants from water. The adsorption of nicotine was studied by isothermal microcalorimetry, which provided the heats evolved as a result of adsorption. The values of these heats revealed that the investigated solids are energetically heterogeneous for the adsorption of nicotine from aqueous solution. Additionally, the amounts of adsorbed pollutant were determined and presented in the form of adsorption isotherms. The obtained adsorption isotherms were interpreted using Langmuir, Freundlich, and Sips equations; the latterwasfound to express high level of agreement with experimental data of nicotine adsorption on the investigated solids. The possibilities to regenerate the adsorbents were examined by means of thermogravimetry coupled with mass spectrometry. From all obtained results, it was possible to distinguish zeolite BEA as a material which possesses the capacity for adsorption of nicotine comparable to that of activated carbon
Vesna Rakic, Ljiljana Damjanovic, Vladislav Rac, Dusan Stosic, Vera Dondur, Aline Auroux, Water Research 44 (2010) 2047-2057

B2400 – Heterogeneous catalysis on solids

It is a readily accepted fact that surface heterogeneity leads to a heterogeneous population of active sites on the surface of a catalyst. It is very often discussed but very seldom taken into account in practical cases, simply because there are very few tools with which to study the heterogeneity of active sites in catalysis. Most attempts to do so have been based upon the use of selective poisons. However, thanks to the improved sensitivity of calorimeters and to the development of refined data analysis techniques, adsorption calorimetry can make a significant contribution to the characterization of a catalytic surface [1]. In particular, the surface properties of a solid can be conveniently investigated by studying the adsorption of suitably chosen probe molecules. The amount of heat evolved during the adsorption process is closely related to the adsorbate – substrate bond strength. Furthermore, the differential heat of adsorption is often dependent on the surface coverage of the adsorbate, due to the lateral adsorbate – adsorbate interactions or due to the surface heterogeneity. So the role of the probe is one of the most decisive parameters in the determination of heats of adsorption. Moreover many catalytic reactions are structure sensitive, and proceed at a rate that depends on the detailed geometric structure of the surface atoms of the catalyst
Ljiljana Damjanovic, Aline Auroux, Handbook of Thermal Analysis and Calorimetry, Vol.5, Recent advances, techniques and applications, Chapter 11, 2008

B2396 – Acidity and Basicity:Determination by Adsorption Microcalorimetry

We review the use of adsorption microcalorimetry for the determination of the surface acidity and basicity of various types of zeolites and related materials, as well as the relationship between the information gathered by this technique and catalytic activity.
Aline Auroux, Molecular Sieves, Springer-Verlag Berlin Heidelberg 2006

B2386 – Heat of adsorption for NH3, NO2 and NO on Cu-Beta zeolite using microcalorimeter for NH3 SCR applications

Microcalorimetry is a powerful technique with which to measure the heat of adsorption (DH), producing values that are very important when developing kinetic models. The method provides a way of determining these parameters independently. For kinetic models describing NH3 SCR it is critical to be able to accurately describe the storage of ammonia and NOx in order to simulate rapid transients occurring in the experiments. The objective of our study is to measure the heat of adsorption of NH3, NO2 and NO on Cu-Beta. An ammonia TPD experiment was conducted at 150°C using the microcalorimeter, resulting in the observation of an exotherm when introducing ammonia due to adsorption. This resulted in an average heat of adsorption of 100 kJ/mol. A good reproducibility was found when using a second sample, resulting in 97 kJ/mol. In order to investigate the coverage dependence of the heat of adsorption, an ammonia stepwise experiment was conducted. First, the catalyst was exposed to NH3 at 500°C, resulting in the adsorption of strongly bound ammonia and obtaining a heat of adsorption of 110 kJ/mol. Thereafter, the catalyst was cooled in Ar and at 400 8C, NH3 was again introduced. Due to that the temperature is lower the ammonia that adsorbed was weaker. The procedure was repeated at 300, 200 and 100°C, resulting in a coverage dependent activation energy for ammonia desorption (if assuming zero activation for adsorption) according to the following formula: Edesorption,NH3 = 120.0 (1 - 0,38?NH3 ) where ?NH3 is the coverage of ammonia on the surface. The NO and NO2 adsorption and desorption were investigated using NO and NO2 TPD experiments, respectively. For the NO2 TPD experiment, approximately three NO2 were stored for each NO produced, corresponding to the disproportionation mechanism. This resulted in DH of 65 kJ/mol per NO2 consumed. The NO TPD experiment resulted in that only small amounts of NO was adsorbed.
Norman Wilken, Krishna Kamasamudram, Neal W. Currier, Junhui Li, Aleksey Yezerets, Louise Olsson, Catalysis Today 151 (2010) 237–243

B2378 – The use of a heat-flow differential scanning calorimeter as a plug-flow fixed bed reactor in heterogeneous catalysis

Some aspects of the use of a heat-flow differential scanning calorimeter for studying catalysts are described in this study. The DSC is coupled to a mass spectrometer in order to analyse the gas mixture that leaves the catalyst bed in the DSC reactor. DSC is a physical means of analysis: it does not disturb the reaction. Attention is focused on the calibration of the DSC with a probe on the basis of the so-called Joule effect. The calibration is carried out over a large temperature range of 300-700 K both in the absence of flow and under flow conditions.
J.J.P. Biermann, P.P. Coelen, H. Den Daas, F.J.J.G. Janssen, Thermochimica Acta, 144 (1989) 329-337

B2377 – Base adsorption calorimetry for characterising surface acidity: a comparison between pulse flow and conventional “static” techniques

A pulsed flow adsorption microcalorimeter (pulse-FMC) has been developed by modifying a Setaram 111. It is tested in comparison with a conventional pulsed static adsorption microcalorimeter (pulse-SMC) for characterising surface acidity of solid acid catalysts. Small pulses of 1% ammonia in helium are delivered to an activated catalyst sample and its surface acidity is differentially profiled in terms of the molar enthalpy of ammonia adsorption ( ?Ho ads) using a combination of differential scanning calorimeter (DSC) and a downstream thermal conductivity detector (TCD). The pulsing action and its sequences are controlled by in-house developed software and the TCD output also is logged into a PC. Thus, the pulse-FMC is fully automated. Two sulfonated polystyrene resin-type catalysts, Amberlyst 15 and Amberlyst 35, a zeolite of the type H+-ZSM-5 (CT 410) and an acid activated clay (Fulcat 220) are characterised at appropriate temperatures using both the new technique and the conventional static base adsorption method. ( ?Ho ads) versus surface coverage profiles of all the four catalysts obtained from both pulse-FMC and the conventional method are found to be comparable. Results are interpreted in terms of the extent to which NH3 adsorption on the catalysts surface is under thermodynamic control in the two methods.
S.P. Felix, C. Savill-Jowitt, D.R. Brown, Thermochimica Acta 433 (2005) 59–65

B2376 – Calorimetric methods for catalytic investigations of novel catalysts based on metallized S-layer preparations

The contribution will show the first results from calorimetric screening of novel catalysts. Biotemplated platinum nanoclusters were prepared on the basis of S-layer—bacterial surface proteins—on different supports. Methods were contrived and examined, permitting both the investigation of catalytic bulk material, and the investigation of sensory interesting coatings. The calorimetric measurements were carried out using conventional calorimetric technique (DSC 111, firm SETARAM) and miniaturized calorimetric systems (integrated circuit calorimeter – IC-calorimeter and a sensor platform). The results of the calorimetric investigations to the selected model reactions (oxidation of hydrogen, carbon monoxide and propane) demonstrate the interesting characteristics of these new catalysts
R. H¨utt, F. Ullrich, G. Wolf, A. Kirchner, M. Mertig, W. Pompe, Thermochimica Acta 440 (2006) 13–18

B2285 – Preparation by atomic layer deposition and characterization of active sites in nanodispersed vanadia/titania/silica catalysts

The dispersion, acidity, reducibility and adsorption capacities of nanostructured, atomic layer deposited (ALD) V2O5/TiO2/SiO2 catalysts were examined by BET, XRD, FTIR and Raman spectroscopy, XPS, H2-TPR and microcalorimetry. TiO2-supported and standard liquid-phase impregnated catalysts were characterized for comparison, and the influence of the catalyst properties on their performance was probed in a test reaction of o-xylene selective oxidation. Gas-phase deposited, isolated vanadia species were highly dispersed independently of the support nature, whereas crystalline vanadia was detected in the impregnated catalysts with submonolayer coverage of titania. Likewise, the reducibility of the ALD catalysts was enhanced in relation to the corresponding impregnated catalysts. The activity of the ALD and impregnated catalyst increased with the decrease in number of strong surface Lewis acid and o-xylene adsorption sites. o-Xylene conversion was greater on the highly dispersed ALD catalysts on TiO2, and on TiO2/SiO2 supports with high titania content, than on their impregnated counterparts.
J. Keränen, P. Carniti, A. Gervasini, E. Iiskola, A. Auroux, L. Niinistö, Catalysis Today 91-92 (2004) 67-71

B2281 – Synthesis and catalytic behaviour of heterogenized rhodium catalysts on modified clays

Rhodium catalysts were synthesised by hydrogen reduction at atmospheric pressure of a cationic organometallic rhodium complex (using [Rh(Me2CO)x(NBD)]ClO4 as the metal precursor species, in which (NBD) is 2,5-norbornadiene and (Me2CO)x is acetone) and anchored onto modified clays: laminar and zeolitic products. The zeolitic products were synthesised under different treatment conditions and in different media, distilled water and seawater; the laminar products consisted of one pillared clay sample and homogenised montmorillonite. The rhodium catalysts were applied in the transformation of acetone. The reaction was carried out at atmospheric pressure and low temperature, after activation at different temperatures. Activity, selectivity and durability depend on the nature of the support used in the preparation of the catalyst. The acidic centres of the pillared montmorillonite favored the formation of methyl isobutyl ketone (MIBK), whereas the other heterogeneous catalysts favored greater selectivity towards isopropanol (IPA). Except the homogenised montmorillonite, the products used as supports in the heterogeneous catalysts showed catalytic activity, although much lower than those prepared by anchoring rhodium on them.
R. Ruiz, C. Pesquera, F. Gonzalez, C. Blanco, Applied Catalysis A: General 257 (2004) 165-175

B2256 – Ca-doped chromium oxide catalysts supported on alumina for the oxidative dehydrogenation of isobutane

The oxidative dehydrogenation (ODH) of isobutane has been investigated on Ca-doped chromium oxide catalysts supported on gamma-Al2O3. The effect of Ca loading on the micro-structural properties of chromia catalysts was investigated by chemical analysis, X-ray diffraction (XRD), scanning electron microscopy with elemental mapping (SEM-EDX), UV-Vis diffuse reflectance spectroscopy (DRS), temperature programmed reduction (TPR), and micro-calorimetry of adsorbed NH3. Cr3+ and Cr6+ species dispersed on alumina, as well as alpha-Cr2O3 and CaCrO4 crystallites, were found on the catalysts surface. The relative amount of the chromium species depends on the Ca loading. The Cr3+/Cr6+ ratio decreases on increasing the Ca loading due to the preferred formation of bulk chromate species. The Ca loading affects the reducibility of the Cr6+ species and the acid sites strength distribution of the catalysts. The catalytic activity in the ODH reaction of isobutane is enhanced in the presence of amounts of calcium <2 wt.%, then it decreases with a further increase in the Ca content. The selectivity to isobutene follows the same trend showing a maximum (57% at 7% isobutane conversion) on the sample promoted with 2 wt.% of calcium. The reported data suggest that the activity and selectivity to isobutene are due to well-dispersed Cr6+ species on the alumina surface, whereas bulk chromates are less active and give mainly COx. On the basis of micro-structural and catalytic results we proposed that the alkali promoter plays different roles depending on the Ca/Cr ratio. Besides causing changes in surface acidity, calcium increases the amount of well-dispersed Cr6+ species in the range of low Ca/Cr ratios, enhancing the catalytic properties, whereas, at higher Ca/Cr ratios, it acts as a poison promoting the formation of the less active and selective bulk chromate species.
G. Neri, A. Pistone, S. De Rossi, E. Rombi, C. Milone, S. Galvagno, Applied Catalysis A: General 260 (2004) 75-86

B2255 – Fries rearrangement of aryl esters catalysed by heteropoly acid: catalyst regeneration and reuse

Heteropoly acid H3PW12O40 (PW) supported on silica and its salt Cs2.5H0.5PW12O40 (CsPW), previously found as active solid acid catalysts in the liquid-phase Fries rearrangement of aryl esters, have been studied for the rearrangement of phenyl acetate and naphthyl acetate in a batch reactor. During the reaction even in nonpolar solvents such as dodecane, PW leached from the silica support. No leaching was found for CsPW in polar (nitrobenzene) or nonpolar (dodecane) solvents. Significant coking was observed for the high-porous PW/SiO2 (6-13 wt.% carbon), whereas the low-porous CsPW built only about 2 wt.% carbon. Both catalysts could be separated by filtration and, after a simple workup (washing with dichloroethane), reused, albeit with reduced activity. The reusability of CsPW improved when the workup included air calcination at 350°C, followed by steaming at 200°C. Doping CsPW with Pd (ca. 2%) allowed full regeneration of catalyst activity and selectivity in phenyl acetate (PhOAc) rearrangement by the air calcination and steaming.
E.F. Kozhevnikova, E. Rafiee, I.V. Kozhevnikov, Applied Catalysis A: General 260 (2004) 25-34

B2246 – Surface acidities and catalytic activities of acid-activated clays

Two commercially available acid-activated montmorillonite clay catalysts, K5 and K10, have been characterised by ammonia adsorption microcalorimetry at 150°C. The adsorption capacities and molar enthalpies of adsorption have been interpreted in terms of the concentration and strength of surface acid sites. Clays exchanged with Al3+, Fe3+ and Na+ have been examined. Catalytic activities have also been measured, in liquid phase reactions in swelling and non-swelling solvents, and in reactions catalysed by Bronsted and by Lewis acid sites. The relationships between ammonia adsorption characteristics and catalytic activities have been determined. It has been shown that anhydrous ammonia is able to access all acid sites on the clay surface, including those in the residual clay interlayer regions which would normally only be accessible in the presence of a swelling solvent. Ammonia adsorption on clays exchanged with Fe3+, where Lewis acidity is maximised, is more extensive and with a higher molar enthalpy of adsorption than on clays maximised for Bronsted acidity. It is concluded that ammonia can be satisfactorily used as a probe of surface acidity when Bronsted acidity dominates but, if there is significant Lewis acidity, ammonia adsorption data is difficult to interpret.
M.P. Hart, D.R. Brown, Journal of Molecular Catalysis A: Chemical 212 (2004) 315-321

B2245 – Steam reforming of methanol to H2 over nonreduced Zr-containing CuO/ZnO catalysts

Zr-containing CuO/ZnO catalysts are examined for their use in the reaction of methanol with water to produce hydrogen. Catalyst samples with varying compositions were prepared by means of a coprecipitation method, and the effect of different pretreatment conditions was examined. Activity testing shows that the catalysts do not require prereduction to obtain good activity for the steam reforming of methanol, although prereduction with diluted H2 increases activity in some cases. The catalysts were characterized using BET surface area analysis, Cu surface area analysis, temperature-programmed reduction (TPR), temperature-programmed desorption (TPD), thermo-gravimetric analysis with differential scanning calorimetry (TGA/DSC), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Characterization suggests that the most active steam-reforming catalysts initially consist of CuO, ZnO, and a high surface area amorphous phase of zirconia that contains carbonates; however, partial reduction of surface copper during the reaction is apparent from XPS results.
P.H. Matter, D.J. Braden, and U.S. Ozkan, Journal of Catalysis 223 (2004) 340-351

B2244 – OsHCl(CO)(PiPr3)2 as catalyst for ring-opening metathesis polymerization (ROMP) and tandem ROMP-hydrogenation of norbornene and 2,5-norbornadiene

Complex OsHCl(CO)(PiPr3)2 catalyzes the ring-opening metathesis polymerization (ROMP) of norbornene and 2,5-norbornadiene to give poly(norbornene) and poly(norbornadiene), respectively. In both cases the resulting polymers have a high cis (74-95%) content. The stereoregularity or tacticity of the cyclopentane and cyclopentene ring sequences in poly(norbornene) and poly(norbornadiene) estimated from the 13C{1H} NMR spectra of the hydrogenated derivatives was found to be syndiotactic. Complex OsHCl(CO)(PiPr3)2 is also active in tandem ROMP-hydrogenation of norbornene and 2,5-norbornadiene. At 40°C and 3 atm of H2, poly(norbornene) is fully hydrogenated in 48 h, while poly(norbornadiene) is fully hydrogenated in 48 h at 75°C and 3 atm of H2. The complex RuHCl(CO)(PiPr3)2 is also active in ROMP and tandem ROMP-hydrogenation of norbornene, obtaining trans-poly(norbornene) and hydrogenated poly(norbornene), respectively.
N. Cobo, M.A. Esteruelas, F. Gonzalez, J. Herrero, A.M. Lopez, P. Lucio, and M. Olivan, Journal of Catalysis 223 (2004) 319-327

B2231 – A calorimetric study of the acidity of bulk and silica-supported heteropoly acid H3PW12O40

The acid strength of bulk and SiO2-supported (10-60 wt%) H3PW12O40 (PW) is characterised by differential scanning calorimetry of ammonia adsorption in a gas-solid system and by microcalorimetry of pyridine adsorption in a liquid-solid system (cyclohexane slurry). In both systems, the strength of PW in terms of the heat of adsorption of NH3 or pyridine increases with increasing PW loading on silica, the bulk PW being the strongest acid. The temperature and the heat of NH3 desorption are shown to indicate the acid strength, in full agreement with the heats of NH3 adsorption. Attempts to measure the acidity of PW included in a sol-gel silica matrix have failed due to a large amount of water present in such systems.
E.F. Kozhevnikova and I.V. Kozhevnikov, Journal of Catalysis 224 (2004) 164-169

B2230 – Effect of surface acidity on the behaviour of Fe-MFI catalysts for benzene hydroxylation to phenol

FTIR and microcalorimetric analysis of adsorbed pyridine has been employed for the characterisation of a set of Fe-MFI zeolite catalysts with different Si/Al and Si/Fe ratios, used for the gas phase hydroxylation of benzene to phenol by N2O. Catalysts behaviour in terms of activity and deactivaton rate is discussed in relation to the nature, concentration and strength of their surface acid sites. Surface acidity, though not involved directly in the hydroxylation reaction, plays a major role in determining catalyst lifetime. Coke formation, leading to catalyst deactivation, is triggered by further undesired reactions of phenol and is favoured by the strong adsorption of the latter on Lewis acid sites, restraining its diffusion out of the zeolite pores.
E. Selli, I. Rossetti, D. Meloni, F. Sini, L. Forni, Applied Catalysis A: General 262 (2004) 131-136

B2219 – Effect of MgO additive on catalytic properties of Co/SiO2 in the dry reforming of methane

The dry reforming of methane to syngas was studied in the temperature range 500-800°C on a series of Co/SiO2 catalysts modified by MgO (5-35 wt.%). The materials have been prepared by successive incipient wetness impregnation and characterised by BET, XRD, H2-TPR, CO2 adsorption and in situ-DRIFT. The formation of a silicate adlayer Mg2SiO4 is observed at high MgO content (30-35 wt.%), which corresponds to a much improved catalytic stability under the severe dry reforming conditions. This phase favours the development of small metallic cobalt particles, preventing their coalescence under reaction conditions. A bi-functional mechanism is proposed which combines the accumulation of oxidizing agents like carbonates and hydrogeno-carbonate adspecies on the catalyst support due to a medium basicity of the layer and the reactivity of small metal particles for methane activation. This concerted process tends to limit coke formation and therefore contribute to the observed catalytic stability.
R. Bouarab, O. Akdim, A. Auroux, O. Cherifi, C. Mirodatos, Applied Catalysis A: General 264 (2004) 161-168

B2209 – Toluene ammoxidation on alpha-Fe2O3-based catalysts

The catalytic behaviour of alpha-Fe2O3-based catalysts in the toluene ammoxidation reaction was investigated in a continuous fixed-bed microreactor at 673 K, under atmospheric pressure. Catalysts were prepared and characterized by chemical analysis, N2 adsorption/desorption at 77 K, X-ray diffraction (XRD), temperature-programmed reduction (TPR) and adsorption microcalorimetry of ammonia. Differences in the reducibility of the surface sites were found between the pure Fe2O3 and the Na silicate containing catalysts. Doping by addition of V2O5, Sb2O5 or Cr2O3 did not lead to a significant modification of the reduction behaviour. On the contrary, the acidic properties of iron oxide were significantly affected by the presence of both Na silicate and V, Sb or Cr metal oxides. The addition of these minor components resulted in the improvement of the catalytic performance of the pure alpha-Fe2O3.
E. Rombi, I. Ferino, R. Monaci, C. Picciau, V. Solinas, R. Buzzoni, Applied Catalysis A: General 266 (2004) 73-79

B2198 – A Ce-promoted Ni-B amorphous alloy catalyst (Ni-Ce-B) for liquid-phase furfural hydrogenation to furfural alcohol

A Ce-doped Ni-B amorphous catalyst (Ni-Ce-B) was prepared by chemical reduction of mixed NiCl2 and CeSO4 with KBH4 in aqueous solution. During liquid-phase hydrogenation of furfural (FFR), all the as-prepared Ni-Ce-B amorphous catalyst exhibited excellent selectivity to furfural alcohol (FFA) owing to the unique amorphous structure and the electronic interaction between the metallic Ni and the alloying B. With the increase of the Ce dopant, the activity first increased and then decreased. The optimum Ce/(Ce + Ni) molar ratio (XCe) was determined as 1.28%. The X-ray photoelectron spectroscopy (XPS) spectra revealed that most of the Ce species in the Ni-Ce-B sample were present in the form of Ce2O3. On one hand, the Ce2O3 might serve as a support for the Ni-B amorphous alloy particles, resulting in the higher surface areas (SBET). On the other hand, the Ce2O3 might serve as a Lewis acid which could strongly adsorb and further polarize the CMO group in the FFR molecule. These two factors could successfully account for the promoting effect of the Ce dopant on the hydrogenation activity of the Ni-B amorphous alloy. Very high content of the Ce dopant (XCe>1.28%) resulted in the decrease of the hydrogenation activity because too many Ni active sites were covered by Ce2O3 species. Treatment of the Ni-Ce-B catalyst at high temperature also caused a decrease in activity due to the transformation from the amorphous structure to the crystalline structure and the loss of the surface area.
H. Li, S. Zhang, H. Luo, Materials Letters 58 (2004) 2741-2746

B2194 – Surface study of rhodium nanoparticles supported on alumina

Two rhodium catalysts supported on alumina (metal loading 1 and 3 wt.%) were comparatively studied by H2 and CO adsorption microcalorimetry and by infrared spectroscopy of the chemisorbed CO. The correlation of the results obtained from these two techniques with the n-butane hydrogenolysis reaction test provides useful information about the type and distribution of the surface active sites. The energetic distribution of surface sites has been shown to depend slightly on the metal loading and it can be modified by the pretreatment conditions. The obtained results also reveal the presence of partially reduced Rh atoms stabilized by Cl ions remaining from the precursor. On the other hand, the increased density on Rh (1 1 1) planes on the sample with 3 wt.% Rh treated with water, detected from CO adsorption experiments, can be related with enhanced both activity for the hydrogenolysis reaction and selectivity towards ethane.
A. Maroto-Valiente, I. Rodriguez-Ramos, A. Guerrero-Ruiz, Catalysis Today 93-95 (2004) 567-574

B2185 – The use of microcalorimetry to assess the size exclusion properties of carbon molecular sieves

Carbon molecular sieves (CMSs) for separating gaseous mixtures have been prepared through chemical vapour deposition (CVD) of benzene on activated carbon fibres (ACFs) obtained from Nomex aramid fibres. The effect of the CVD treatment on the porous texture of the ACFs has been followed by immersion calorimetry into liquids of different molecular sizes (dichloromethane, benzene and cyclohexane). Both the kinetics of the immersion process and the equilibrium immersion enthalpies have been studied. Besides, the derived specific surface areas accessible to the different liquids employed have been calculated. The results show that the carbon deposition has taken place mainly at the pore entrances and the CVD treatment has succeeded to introduce selectivity without a significant loss of capacity.
S. Villar-Rodil, R. Denoyel, J. Rouquerol, A. Martinez-Alonso, J.M.D. Tascon, Thermochimica Acta 420 (2004) 141-144

B2179 – Surface characteristics and activity in selective oxidation of o-xylene of supported V2O5 catalysts prepared by standard impregnation and atomic layer deposition

Alumina-, silica-, and titania-supported vanadium oxide systems with V2O5 loadings ranging from 3 to 12 wt.%, corresponding to 0.02- 0.09 V/(Al,Si,Ti) atomic ratios, were prepared by atomic layer deposition (ALD) and compared with the corresponding impregnated catalysts. The surface acidic properties of the supports and catalysts were investigated using ammonia adsorption microcalorimetry to determine the number and strength of the surface acid sites. Deposition of V2O5 on alumina and titania supports gave rise to catalysts with lower amounts of acid sites than the respective supports, while for the samples prepared on silica, an increase of the number of acid sites was observed after V2O5 deposition. As a common trend, the surface acid strength was greater for the ALD catalysts than for the impregnated ones, suggesting a stronger interaction of the VO species with the support centers, which act as electron attractor centers creating Lewis-like vanadium species. Redox cycles were performed, involving temperature programmed reduction (TPR) analyses separated by an oxidation treatment (TPO). The results evidenced the good reversibility of the redox behavior of the vanadium centers in every case, while significant differences were observed when comparing the temperatures of reduction (Tmax). Lower Tmax values were observed for the better dispersed vanadia catalysts. After reduction, the V centers had a final formal average oxidation state corresponding to +3 or less (+2.5 to +2). The reactivity of the vanadia systems was examined by measuring their performance for the oxidation of o-xylene to phthalic anhydride. Activity tests indicated the superior selectivity of the V2O5 systems based on the more acidic supports (Al2O3 and TiO2). The nature of the support governed the activity, and the more concentrated catalysts gave rise to improved selectivity to phthalic anhydride.
A. Gervasini, P. Carniti, J. Keränen, Lauri Niinistö, A. Auroux, Catalysis Today 96 (2004) 187-194

B2178 – Sol-gel synthesis, characterization and catalytic properties of Fe-Ti mixed oxides

Fe2O3-TiO2 solid acid catalysts have been prepared by a sol-gel route, characterized and tested in the isomerization of a-pinene oxide. The textural, morphological and microstructural characterization of the catalysts was carried out by BET surface area measurements, X-ray diffraction (XRD) and scanning electron microscopy with elemental X-ray analysis (SEM-EDX). Characterization data have shown that, on the pure TiO2 catalyst, titania is mainly in the anatase phase. On the contrary the rutile phase and/or Fe2TiO5, amorphous iron-titanium mixed oxides and hematite were found on the Fe-promoted TiO2 catalysts, depending on the Fe content. Temperature programmed desorption (TPD), microcalorimetry and FT-IR spectroscopy of adsorbed probe basic molecules (ammonia or pyridine) have shown that addition of iron to titania favours formation of new acid sites having a stronger Lewis character. Fe2O3-TiO2 catalysts show a higher activity compared to pure titania in the isomerization of a-pinene oxide to campholenic aldehyde. The products distribution was also influenced by the composition of the catalysts. A correlation between the selectivity to campholenic aldehyde and the amount of Lewis acid sites on the catalysts was found. Based on the characterization and catalytic results, Fe-Ti-O mixed structures were proposed to be the active sites for the selective isomerization of a-pinene oxide to campholenic aldehyde.
G. Neri, G. Rizzo, S. Galvagno, G. Loiacono, A. Donato, M.G. Musolino, R. Pietropaolo, E. Rombi, Applied Catalysis A: General 274 (2004) 243-251

B2173 – Surface study of graphite-supported Ru-Co and Ru-Ni bimetallic catalysts

Several graphite-supported Ru-Co and Ru-Ni bimetallic catalysts were comparatively studied by X-ray diffraction (XRD) and CO adsorption microcalorimetry. The correlation of the results thus obtained from these techniques with those on the n-butane hydrogenolysis reaction test, provides useful information about the type and distribution of the surface active sites. The CO adsorption microcalorimetry technique provides, in some cases, information that allows identification and quantification of the surface sites of the metallic nanoparticles. Thus, these data may be used to identify specific catalytic properties (activity and selectivity) in the n-butane/hydrogen test, and how such properties are modified on the different surface sites. Also, comparison with the parent monometallic catalysts allows to envisage the contribution of each individual metal to the total surface composition or else of the formation of alloys or bimetallic surface clusters. The results so obtained suggest the formation of surface Ru-Co and Ru-Ni alloys on these bimetallic catalysts, their contribution to the surface composition depending on the relative atomic ratio (Ru/M) and on the pre-treatment (reduction) conditions.
M. Cerro-Alarcon, A. Maroto-Valiente, I. Rodriguez-Ramos, A. Guerrero-Ruiz, Applied Catalysis A: General 275 (2004) 257-269

B2164 – Cracking and aromatization properties of some metal modified ZSM-5 catalysts for light alkane conversions

ZSM-5 (HZ) was prepared by hydrothermal synthesis and, zinc and gallium incorporated ZSM-5 catalysts were prepared by adopting incipient wet impregnation (ZnHZ, GaHZ) and co-synthesis methods (Zn-Al-Si and Ga-Al-Si). The acidity and strength distribution of acid sites were measured by micro-calorimetric ammonia adsorption, where Zn-Al-Si and Ga-Al-Si exhibited lower acidity values when compared to the HZ, ZnHZ and GaHZ samples. The n-heptane aromatization activity of the catalysts is in the order of Zn-Al-Si > Ga-Al-Si > ZnHZ ~ GaHZ > HZ. The Zn-Al-Si catalyst exhibited the lowest acidity but highest aromatization activity with stable performance in the studied period of 360 min. The catalyst exhibited greater than 80% conversions with 50-65 wt.% selectivity to aromatics for the conversion of various industrial feedstocks namely NGC, light naphtha and raffinate. The major byproduct in this reaction is 21-33 wt.% LPG that makes the catalyst promising for industrial application.
N. Viswanadham, G. Muralidhar, T.S.R. Prasada Rao, Journal of Molecular Catalysis A: Chemical 223 (2004) 269-274

B2162 – Mechanochemically synthesized nano-dimensional iron-cobalt spinel oxides as catalysts for methanol decomposition

Iron-cobalt spinel oxide nanoparticles with different Fe/Co ratios have been prepared by the combination of chemical precipitation with simultaneous ultrasonic treatment and subsequent mechanical milling. For comparison, their analogues obtained by thermal synthesis were also studied. Phase composition and structural properties of iron-cobalt oxides are investigated by X-ray diffraction and Moessbauer spectroscopy. Their catalytic behavior in methanol decomposition to CO and methane is tested. A well-defined effect of the preparation method and Fe/Co ratio on the reduction and catalytic properties of iron-cobalt samples is established.
E. Manova, T. Tsoncheva, D. Paneva, I. Mitov, K. Tenchev, L. Petrov, Applied Catalysis A: General 277 (2004) 119-127

B2161 – Performance of PtSn catalysts supported on MAl2O4 (M: Mg or Zn) in n-butane dehydrogenation: characterization of the metallic phase

The Sn(0.3 or 0.5 wt.%) addition to Pt(0.3 wt.%)/ZnAl2O4 and Pt(0.3 wt.%)/MgAl2O4 catalysts leads to an increase of the activity and selectivity to olefins in the n-butane dehydrogenation reaction. Slight differences in the catalytic behaviour were found between 0.3 and 0.5 wt.% of Sn added to Pt in both catalyst series. Besides, the bimetallic catalysts also show a good stability through the five successive reaction-regeneration cycles, mainly the PtSn/MgAl2O4 one. The mono- and bimetallic catalysts were characterized by using different techniques: tests reactions of the metallic phase (cyclohexane dehydrogenation and cyclopentane hydrogenolysis), temperature programmed reduction, X-ray photoelectron spectroscopy, H2 chemisorption, microcalorimetric measurements of the propylene adsorption and XRD. Results show that the nature of the metallic phase in monometallic samples appears to be different for the two supports. Thus, metallic particles with a very low concentration of hydrogenolytic sites (steps, corners and edges) would exist in the Pt/ZnAl2O4 catalyst in contrast with the structure of the metallic phase of the Pt/MgAl2O4 one, where the existence of an important concentration of hydrogenolytic sites is clearly observed (according to the cyclopentane hydrogenolysis results). The modification of Pt by the Sn addition clearly improves the catalytic behaviour in n-butane dehydrogenation due to important changes in the structure of the metallic phase. Thus, when Sn is added to Pt/ZnAl2O4 and Pt/MgAl2O4 catalysts the metallic surface structure seems to be more complex. In fact, results would indicate not only a partial formation of PtSn alloys or intermetallic compounds between Pt° and a fraction of Sn(0), but also a surface enrichment in Sn, dilution effects as well as the presence of tin stabilized on the support, probably as Sn(II/IV) oxides and SnCl2 species.
S.A. Bocanegra, A. Guerrero-Ruiz, S.R. de Miguel, O.A. Scelza, Applied Catalysis A: General 277 (2004) 11-22

B2124 – Acid properties of semicrystalline zeolitic mesoporous UL-ZSM-5 materials

UL-ZSM-5 materials have been prepared by templated solid-state crystallization of zeolites starting from the amorphous mesostructured aluminosilicate Al-Meso. Microcalorimetry and FTIR have been employed to characterize their surface acidity. In good agreement with 27Al MAS NMR data, UL-ZSM-5 displayed an improved density and strength of Brönsted acid sites, as compared to Al-Meso, owing to the incorporation of aluminium in a tetrahedral environment similar to that of zeolite ZSM-5. Moreover, they showed an enhanced Brönsted/Lewis relative acid ratio. However, Al-Meso showed the highest concentration of strong Lewis acid sites due to its largest amount of aluminium in extraframework positions.
A. Ungureanu, H.V. Thang, D. Trong On, E. Dumitriu and S. Kaliaguine, Journal of Thermal Analysis and Calorimetry 87 (2007) 417-422

B2103 – Catalytic nitroxidation of 1-methylnaphthalene I. Preparation, characterisation and NO-surface interactions of chromia/alumina-based catalysts

In view of their use in the nitroxidation of 1-methylnaphthalene into 1-naphthonitrile, chromia/alumina and K-containing chromia/alumina catalysts were prepared. They were characterised by X-ray diffraction, scanning electron microscopy, nitrogen physical adsorption, UV-vis diffuse reflectance spectroscopy, adsorption microcalorimetry of ammonia and carbon dioxide, temperature-programmed reduction. The interaction of NO with the catalyst surface was investigated by temperature-programmed methods. Both Cr(III) and Cr(VI) species were found on the catalysts, the content of the latter increasing along with the K loading. A bichromate phase was detected in the K-containing catalysts. Cr(VI) species underwent (incomplete) reduction under hydrogen atmosphere. The reduction extent was higher at the higher K loadings, though higher energy barriers needed to be overcome for its occurrence. All the catalysts were able to dissociate NO into atomic nitrogen and oxygen and also to convert NO into N2O and O2 in the temperature range 623-657 K. NO disproportionation occurred on the K-containing chromia/alumina catalysts even at relatively low temperatures (372-407 K), but not on chromia/alumina. Chromia/alumina showed an acidic as well as a basic character, the acid features being however predominant. At the lowest K content acidity appeared remarkably lowered and basicity significantly increased. Further addition of K originated a catalyst somewhat balanced in its (weak) acid-base character. At the highest K loadings the original acidic and basic features of chromia/alumina were completely lost. Such different redox and acid-base features, as well as the different interaction modes with NO, are expected to influence deeply the catalytic behaviour in 1-methylnaphthalene nitroxidation.
E. Rombi, M.G. Cutrufello, S. De Rossi, M.F. Sini, I. Ferino, Journal of Molecular Catalysis A: Chemical 247 (2006) 171-181

B2091 – Adsorption and differential heats of adsorption of normal and iso-butane on zeolite MFI

Adsorption of n- and i-butane on zeolite MFI (silicalite type) at different temperatures has been investigated using a manometric technique combined with a micro-calorimeter. The Langmuir model can describe the isotherms for both components. The derived thermodynamic properties are in agreement with the literature data from other techniques. The differential heats of adsorption when plotted against loading present an initial plateau; followed by a slow rise, which can be attributed to adsorbate-adsorbate interactions. For i-butane these adsorbate-adsorbate interactions give rise to a sharp peak in heat of adsorption versus loading, at 0.6 mmol/g. A decrease at higher loadings on the heat of adsorption is observed for both isomers, this is attributed to surface adsorption.
A.F.P. Ferreira, M.C. Mittelmeijer-Hazeleger, A. Bliek, Microporous and Mesoporous Materials 91 (2006) 47-52

B2076 – Acid site accessibility in sulfonated polystyrene acid catalysts: Calorimetric study of NH3 adsorption from flowing gas stream

Calorimetric pulsed NH3 adsorption measurements from a flowing carrier gas have been made on sulfonated poly(styrene-co-divinylbenzene) resin acid catalysts to characterise surface acidity in general and acid site accessibility in particular. The adsorption and enthalpy profiles associated with each pulse of NH3 show distinct features associated with relatively weak and reversible adsorption of NH3 followed by strongly exothermic reaction with sulfonic acid sites and irreversible adsorption. The rate at which NH3 diffuses from its initial adsorption site to an acid site is shown to depend on catalyst particle size, adsorption temperature and the proportion of unreacted acid sites. By varying the contact time of NH3 with the catalyst the reversibility of the initial NH3 adsorption is demonstrated and an increasing number of the acid sites within the polymer matrix are shown to become completely inaccessible to NH3 as the contact time is reduced.
P.F. Siril, D.R. Brown, Journal of Molecular Catalysis A: Chemical 252 (2006) 125-131

B2070 – Acylation of 2-methoxynaphthalene with acetic anhydride over silica-embedded triflate catalysts

Silica sol-gel immobilized triflate compounds like La(OTf)3, tert-butyldimethylsilyl trifluoromethanesulfonate (BDMST) and triflic acid (HOTf) were tested in the acylation of 2-methoxynaphthalene with acetic anhydride, leading to 1-acetyl-2-methoxynaphthalene as the major product. The reaction only proceeded with good yields on BDMST and HOTf catalysts, while La(OTf)3 presented a low activity. For BDMST in solvent-free conditions, the resulting TOF was superior to that reported in literature for other heterogeneous catalysts and even for homogeneous triflates. The rates of reactions in various solvents strongly depend on the donor number of these solvents.
A.N. Pârvulescu, B.C. Gagea, V.I. Pârvulescu, D. De Vos, P.A. Jacobs, Applied Catalysis A: General 306 (2006) 159-164

B2068 – Kinetic and calorimetric study of the adsorption of dyes on mesoporous activated carbon prepared from coconut coir dust

Mesoporous activated carbon has been prepared from coconut coir dust as support for adsorption of some model dye molecules from aqueous solutions. The methylene blue (MB) and remazol yellow (RY) molecules were chosen for study of the adsorption capacity of cationic and anionic dyes onto prepared activated carbon. The adsorption kinetics was studied with the Lagergren first- and pseudo-second-order kinetic models as well as the intraparticle diffusion model. The results for both dyes suggested a multimechanism sorption process. The adsorption mechanisms in the systems dyes/AC follow pseudo-second-order kinetics with a significant contribution of intraparticle diffusion. The samples simultaneously present acidic and basic sites able to act as anchoring sites for basic and acidic dyes, respectively. Calorimetric studies reveal that dyes/AC interaction forces are correlated with the pH of the solution, which can be related to the charge distribution on the AC surface. These AC samples also exhibited very short equilibrium times for the adsorption of both dyes, which is an economically favorable requisite for the activated carbon described in this work, in addition to the local abundance of the raw material.
J. de Souza Macedo, N. Bezerra da Costa Junior, L.E. Almeida, E. Fragoso da Silva Vieira, A.R. Cestari, I. de Fatima Gimenez, N.L.V. Carreño, L.S. Barreto, Journal of Colloid and Interface Science 298 (2006) 515-522

B2050 – Effect of Sn addition to Pt/CeO2-Al2O3 and Pt/Al2O3 catalysts: An XPS, 119Sn Mössbauer and microcalorimetry study

The effect of adding Sn to Pt/CeO2-Al2O3 and Pt/Al2O3 catalysts was studied with X-ray photoelectron spectroscopy (XPS), 119Sn Mössbauer spectroscopy, and adsorption microcalorimetry of CO at room temperature. Catalysts were reduced in situ at 473 (non-SMSI state) and 773 K (SMSI state). 119Sn Mössbauer and XPS results indicated that the presence of cerium in bimetallic catalysts inhibited reduction of tin, and that tin facilitated the reduction of cerium(IV) to cerium(III). Microcalorimetric analysis indicated that adding cerium caused the appearance of a more heterogeneous distribution of active sites, whereas adding tin led to a higher homogeneity of these sites. Reduction at 773 K decreased the Pt surface area as measured by CO chemisorption for all catalysts used in this study. Adding tin to Pt/Al2O3 and Pt/CeO2-Al2O3 also decreased the Pt surface area due to formation of PtSn and possibly Pt-SnOx species. Adding cerium to Pt/Al2O3 caused a loss of Pt surface area only when the catalyst was reduced at 773 K, presumably due to migration of the reduced cerium onto Pt particles. Adding cerium to Pt/Al2O3 caused an increase in the catalytic activity for crotonaldehyde hydrogenation, whereas adding Sn to Pt/Al2O3 decreased the activity of Pt/Al2O3 catalysts. Higher reduction temperatures caused an increase in the initial catalytic activity for crotonaldehyde hydrogenation for all catalysts studied. Selectivity enhancements for crotyl alcohol formation in crotonaldehyde hydrogenation were observed for the Ce- and Sn-promoted catalysts after reduction at 773 K.
J.C. Serrano-Ruiz, G.W. Huber, M.A. Sanchez-Castillo, J.A. Dumesic, F. Rodriguez-Reinoso, A. Sepulveda-Escribano, Journal of Catalysis 241 (2006) 378-388

B2033 – From molecule to material: Mg2Sn as hydrogenation catalyst

The liquid-phase hydrogenation of citral has been studied for the first time over an ionogenic Zintl phase, Mg2Sn. By using this unsupported alloy, citral conversion was 20% at 448 K and the product mixture was mainly comprised of geraniol, nerol, citronellal and citronellol. The product ratio of the formation of unsaturated allyl-type alcohols to the formation of citronellal + citronellol is similar to that obtained with the unsupported alloy Ru3Sn7 and a silica supported Ru-Sn catalyst. The results clearly indicate that the polar character of active sites is a prerequisite for the chemisorption of the polar C=O group and, thus, must be a key factor in controlling the selectivity of the hydrogenation of alpha,beta-unsaturated aldehydes.
P. Claus, F. Raif, S. Cavet, S. Demirel-Gülen, J. Radnik, M. Schreyer, T. Fässler, Catalysis Communications 7 (2006) 618-622

B2025 – Adsorption of benzothiophene on Y zeolites investigated by infrared spectroscopy and flow calorimetry

Diffuse reflectance infrared spectra of benzothiophene adsorbed on different Y zeolites reveal that the cations and protons in the zeolites are the sites responsible for the adsorption of benzothiophene. On NaY, benzothiophene was molecularly adsorbed on the cations through the electrophilic interaction between the cations and the thiophenic rings. On the transition metal ion exchanged NiY and CuY zeolites, because of the presence of the d-electrons in the cations, the thiophenic rings interact with the cations to form the pi-complexes through the sigma-pi electron donations. In the presence of hydroxyl species in the zeolites, the adsorbed sulfur compounds attach to the protons molecularly via the electrophilic interaction and undergo the opening of the thiophenic rings depending on the acidity of the zeolites and the adsorption amount. The apparent heat of adsorption of benzothiophene in normal octane on the Y zeolites determined by flow calorimetry shows that the adsorption strength based on the measured heat for each mole sulfur adsorbed on the Y zeolite is in the order of CuY > NiY > NaY ~ USY. For USY, due to the endothermic breakage of the thiophenic ring of benzothiophene induced by the acid sites of the zeolite, the apparent heat of adsorption is similar to that obtained from the adsorption on NaY. This work demonstrates that the transition metal ion exchanged zeolites exhibit excellent properties for sulfur adsorption because of the formation of the pi-complexes and that the acidity of the zeolites is not advantageous for sulfur removal due to the strong adsorption and decomposition of the adsorbed species.
M. Jiang, F.T.T. Ng, Catalysis Today 116 (2006) 530-536

B2022 – Effect of preparation technique on the properties of platinum in NaY zeolite: A study by FTIR spectroscopy of adsorbed CO

Two platinum-containing zeolites were studied by XPS, TPR and IR spectroscopy of adsorbed CO. The sample Pt-NaY was prepared by ion-exchange and the Pt/NaY sample, by impregnation. XP spectra indicate a higher heterogeneity of platinum on the impregnated sample and enrichment of its outer surface in platinum, compared to the exchanged sample. Accessible platinum in both activated samples is in the form of metal. However, oxidation of Pt-NaY with a NO+O2 mixture results in creation of cationic sites. Adsorption of CO on the sample thus treated leads to formation of different platinum carbonyls: (i) Pt3+(CO)2 species (2204 and 2168 cm-1) which are decomposed without production of monocarbonyls, (ii) two kinds of Pt2+-CO species (2155 and 2141 cm-1), (iii) Pt+(CO)2 dicarbonyls (2127 and 2091 cm-1) and (iv) linear Pt0-CO species (2080-2054 cm-1). In contrast, almost no cationic sites were produced after the attempts to oxidize the impregnated sample. In both samples Chini-complexes were formed after interaction with CO at 373 K. However, the process was much easier with the impregnated sample. This indicates that exchanged cations, interacting more strongly with the zeolite matrix, are not suitable for preparation of anionic carbonyls. The effect of the preparation technique is discussed and the results are compared with the results on platinum in other zeolites.
K. Chakarova, K. Hadjiivanov, G. Atanasova, K. Tenchev, Journal of Molecular Catalysis A: Chemical 264 (2007) 270-279

B2013 – Effect of the reduction-preparation method on the surface states and catalytic properties of supported-nickel particles

Several high surface area graphite-supported Ni catalysts were prepared and reduced by different methods. Samples were prepared by impregnation of the support and then submitted to traditional H2 flow reduction at high temperature or to reduction with aqueous hydrazine at low temperature, and compared with a sample prepared by the deposition-precipitation method by means of the reduction of the dissolved Ni precursor by hydrazine at low temperature. The surface of these catalysts was characterised by means of CO adsorption microcalorimetry and by X-ray photoelectron spectroscopy (XPS), and a correlation of the results obtained with those on the selective hydrogenation of citral can be done. In this sense, only Ni° sites were detected at the surface of the Ni catalysts prepared by reduction with hydrogen leading to high catalytic activities and selectivity towards citronellal formation, while Ni oxidised species are also present (and are major) for catalysts prepared by reduction with hydrazine, what leads to an enhanced selectivity towards the formation of the unsaturated alcohols, geraniol and nerol. The oxidation of these latter catalysts seems to be only superficial, as suggested by the absence of H2 consumption peaks in the TPR experiments. The presence of Ni° sites over these latter catalysts was not detected by XPS, thus our study proves that CO adsorption microcalorimetry is a very powerful tool for surface characterisation of heterogeneous catalysts.
M. Cerro-Alarcon, B. Bachiller-Baeza, A. Guerrero-Ruiz, I. Rodriguez-Ramos, Journal of Molecular Catalysis A: Chemical 258 (2006) 221-230

B2012 – Effect of acidity and porosity changes of dealuminated mordenites on n-hexane isomerization

A series of dealuminated mordenite samples was prepared and tested for their activity in n-hexane hydroisomerization reaction. The samples were thoroughly characterized by XRD, microcalorimetry, and adsorption measurement to obtain surface area, pore volume and pore size distribution. Both strong acidity ( ?H NH3 > 100 kJ/mol) and micropore volume (0-20 Å) of the mordenite were increased during the initial stage of dealumination. Further dealumination caused very little or negligible improvement in the catalytic properties. Among the various catalysts prepared, the catalyst dealuminated by steaming at 673 K, followed by acid leaching with 2N HNO3 (S2-HM) exhibited highest amount of strong acidity and isomer yields in n-hexane conversion. The selectivity to di-branched isomers was continuously increased with dealumination.
N. Viswanadham, Lalji Dixit, J.K. Gupta, M.O. Garg, Journal of Molecular Catalysis A: Chemical 258 (2006) 15-21

B1996 – Cu hydrotalcite-like compounds: Morphological, structural and microstructural properties

Copper containing mixed oxides are widely employed as catalysts for the synthesis of methanol, higher alcohol, hydrocarbons from syngas at low temperature and pressure, and for NiOx reduction. In this work, a series of Mg-Al-Cu, as hydrotalcite-like compounds (Cu-HTlcs) precursors of mixed oxides were synthesized by direct coprecipitation. The effect of pH, Cu content and mechanical milling on the structure and texture of these materials was investigated. The obtained materials were characterized by X-ray diffraction, differential scanning calorimetry, scanning and transmission electron microscopy and BET surface area measurements. The results showed that the materials were nanocrystalline powders. The Cu-HTlcs has a hexagonal unit cell. The a and c parameters increased as a function of the Cu content in both milled and non-milled samples. Crystallite size also increased with Cu content in both cases and smaller for non-milled samples. In contrast, microstrain values were greater for milled samples. BET area decreased with Cu content and showed that materials synthesized were mesoporous type. Mechanical milling did not destroy the morphology of the samples.
D.R. Suarez, B.H. Zeifert, M.H. Garduno, J.S. Blasquez, A.R. Serrano, Journal of Alloys and Compounds 434-435 (2007) 783-787

B1971 – Surface acidity of niobium phosphate and steam reforming of dimethoxymethane over CuZnO/Al2O3-NbP complex catalysts

Dimethoxymethane (DMM) is nontoxic and of high hydrogen content and may be used as a H2 storage material for small H2 sources. Steam reforming of DMM requires a bifunctional catalyst composed of an acidic component and a traditional copper catalyst, on which DMM is hydrolyzed on the acidic sites to methanol and formaldehyde, which are then further reformed to H2 and CO2 on metallic copper sites. In this work, samples of niobium phosphate with high surface areas were synthesized, characterized, and tested for the hydrolysis of DMM and used as acidic components for the reforming of DMM to produce H2. The structure and surface areas of these samples were characterized, and the activity for the hydrolysis of DMM was correlated with the surface acidities. It was found that all of the niobium phosphate samples exhibited high activity for the hydrolysis of DMM. The one with a high surface area (394 m2/g) was highly acidic with mainly Bronsted acid sites and thus was the most active for the hydrolysis of DMM among the niobium samples studied in this work. Mixing the niobium phosphate with CuZnO/Al2O3 did not affect the activity of CuZnO/Al2O3 for the reforming of methanol. The activity and selectivity to H2 were low for the steam reforming of DMM over traditional CuZnO/Al2O3 alone. Mechanically mixing niobium phosphate with CuZnO/Al2O3 greatly enhanced the conversion of DMM (e.g., 100% at 493 K) with high selectivity to H2. This indicates that niobium phosphate is an effective acidic component for the hydrolysis of DMM and can be used with CuZnO/Al2O3 for reforming DMM to produce H2.
Q. Sun, A. Auroux, J. Shen, Journal of Catalysis 244 (2006) 1-9

B1966 – Acid strengths and catalytic activities of sulfonic acid on polymeric and silica supports

The acidic and catalytic properties of sulfonic acids supported on polystyrene, on silica (via propyl and phenyl tethers) and on a fluorinated hydrocarbon polymer (Nafion) are compared. Surface acidities are characterised using ammonia adsorption calorimetry under flow conditions in which pulses of ammonia are introduced to the sample from a flowing carrier stream. The extent of adsorption and molar enthalpies of ammonia adsorption (?Hads°) are interpreted in terms of the abundance, accessibility and strength of surface acid sites. Catalytic activities are measured for the isomerisation of alpha-pinene. The Nafion catalysts show the highest ?Hads°(NH3) and the highest catalytic activities. Although both silicasupported and polystyrene-supported sulfonic acids show lower specific activities and lower ?Hads°(NH3) values, the correlation between activity and ?Hads°(NH3) is relatively poor for these supported forms of the acid. It appears that while ?Hads°(NH3) is certainly sensitive to the strength of acid groups on which ammonia is adsorbed, it can only be used to compare acid strengths in a meaningful way for structurally similar catalysts.
P.F. Siril, A.D. Davison, J.K. Randhawa, D.R. Brown, Journal of Molecular Catalysis A: Chemical 267 (2007) 72-78

B1964 – Influence of modifiers on the performance of Ru-supported catalysts on the stereoselective hydrogenation of 4-acetamidophenol

Ruthenium-supported catalysts modified by the addition of Mg, Na or Ce were studied in the selective hydrogenation of paracetamol (4- acetamidophenol) to cis- and trans-4-acetamidocyclohexanol. In both series, catalysts supported on carbon or on alumina, the modified catalysts were more selective to the trans isomer than the corresponding monometallic catalysts. However, the modified catalysts, particularly the supported on carbon, were less active. Moreover, there is a reduction in the hydrogenolysis reaction of the OH group on carbon-supported catalysts. The enhancement observed in the stereoselectivity for the modified catalysts may be explained by an alteration in the acid-base properties of the catalyst surface, which eventually control the mode of adsorption of the molecule of paracetamol and probably the tautomeric equilibrium of the 4- acetamidocyclohexene-1-ol intermediate. The optimum amount of promoter to improve the stereoselectivity seems to depend on the inherent acid- base characteristics of both the modifier and the support. Therefore, the proper adjustment or fine tuning of these parameters is crucial for obtaining the best results in terms of stereoselectivity.
B. Bachiller-Baeza, A. Guerrero-Ruiz, I. Rodriguez-Ramos, Applied Surface Science 253 (2007) 4805-4813

B1961 – Aromatics reduction of pyrolysis gasoline (PyGas) over HY-supported transition metal catalysts

The hydrodearomatization of pyrolysis gasoline (PyGas) over bifunctional catalysts, based on noble metals (Pt, Pd, Ir, Ni) supported on a HY zeolite, has been studied in a fixed-bed reactor. The surface structures of the catalysts were determined by CO chemisorption, photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR) and temperature-programmed desorption of H2 (H2-TPD). Catalyst acidity was assessed by ammonia desorption measured by differential scanning calorimetry (DSC-NH3) and Fourier transform infrared spectroscopy of adsorbed pyridine (FTIR-Py). The kinetic performance and product selectivity of the catalysts were discussed in terms of the data provided by surface characterization techniques. Kinetic interpretation was carried out by using individual step conversion, i.e. hydrogenation and ringopening. The results under mild ring-opening (MRO) conditions indicate a strong dependence of the hydrogenation activity on the metal used. Operating under severe ring-opening (SRO) conditions, a linear dependency of conversion and n-alkane yield on total acidity of the catalyst was observed.
P. Castano, B. Pawelec, J.L.G. Fierro, J.M. Arandes, J. Bilbao, Applied Catalysis A: General 315 (2006) 101-113

B1936 – Investigation of the water sorption properties of Mars-relevant micro- and mesoporous minerals

Encouraged by recent results of the Mars Odyssey spacecraft mission and the OMEGA team (Mars Express) concerning water in equatorial latitudes between ±45° on Mars and the possible existence of hydrated minerals, we have investigated the water sorption properties of natural zeolites and clay minerals close to martian atmospheric surface conditions as well as the properties of Mg-sulfates and gypsum. To quantify the stability of hydrous minerals on the martian surface and their interaction with the martian atmosphere, the water adsorption and desorption properties of nontronite, montmorillonite, chabazite and clinoptilolite have been investigated using adsorption isotherms at low equilibrium water vapor pressures and temperatures, modeling of the adsorption equilibrium data, thermogravimetry (TG), differential scanning calorimetry (DSC), and proton magic angle spinning nuclear magnetic resonance measurements (1H MAS NMR). Mg-sulfate hydrates were also analyzed using TG/DSC methods to compare with clay mineral and zeolites. Our data show that these microporous minerals can remain hydrated under present martian atmospheric conditions and hold up to 2.5-25 wt% of water in their void volumes at a partial water vapor pressure of 0.001 mbar in a temperature range of 333-193 K. Results of the 1H MAS NMR measurements suggest that parts of the adsorbed water are liquid-like water and that the mobility of the adsorbed water might be of importance for adsorption-water-triggered chemistry and hypothetical exobiological activity on Mars.
J. Jänchen, D.L. Bish, D.T.F. Möhlmann, H. Stach, Icarus 180 (2006) 353-358

B1933 – Catalytic activity of Bronsted acid sites in zeolites: Intrinsic activity, rate-limiting step, and influence of the local structure of the acid sites

The catalytic activity of Bronsted acid sites in zeolites was studied by the monomolecular conversion of propane over zeolites with varying framework topologies and Si/Al ratios. The rates and apparent activation energies of cracking and dehydrogenation were determined. The activity of the Bronsted acid sites depends on the rate-limiting step of the reaction. In the cracking reaction, the protonation of the alkane is the rate-limiting step, and the heat of reactant adsorption dominates the differences in the observed activity. The similar intrinsic activities over the different zeolites show that the ability of zeolitic Bronsted acid sites to transfer a proton to an alkane does not vary significantly, suggesting that the acid sites that participate in the reaction have very similar strengths. In the dehydrogenation reaction, the rate-limiting step is the desorption of the alkoxide species. The rate is determined by the stability of the alkoxide species, which is influenced by the local geometric and electronic structure of the Bronsted acid site and is affected by zeolite structure and Si/Al ratio. Implications of these conclusions are related to other reactions, such as catalytic cracking and alkylation.
B. Xu, C. Sievers, S.B. Hong, R. Prins, J.A. van Bokhoven, Journal of Catalysis 244 (2006) 163-168

B1921 – Surface and structural effects in the hydrogenation of citral over RuCu/KL catalysts

Four 2 wt% Ru/KL catalysts, doped with copper, were prepared by successive impregnation of a KL zeolite with Ru3(CO)12 and Cu(NO3)2 . 3H2O aqueous solutions in an adequate concentration to obtain 0, 0.5, 1 and 1.5 wt% of copper. The samples Ru/KL, RuCu0.5/KL, RuCu1.0/KL and RuCu1.5/KL were characterized by X-ray diffraction, temperature-programmed reduction, chemisorption of CO and H2, BET surface area, infrared spectroscopy of adsorbed CO and microcalorimetry of CO adsorption. Catalytic activity measurements in the selective hydrogenation of citral, at 323 K and 5 MPa in the liquid phase, showed that copper inhibits the overall hydrogenation activity of Ru/KL catalysts, the higher the copper concentration the larger the activity reduction, without significant modification of the hydrogenation turnover frequencies. Selectivity toward unsaturated alcohols decreases as the copper content increases in favor of that of citronellal. The presence of bimetallic entities on the doped catalysts was suggested by the TPR measurements and the occurrence of hydrogen spillover phenomenon evidenced by the results of the chemisorption measurements of hydrogen and CO. The catalyst behavior is consistent with both, decoration/encapsulation of ruthenium by copper particles and occlusion of Ru inside the zeolite pores. This is suggested by the strong decrease of CO chemisorption capacity of the catalysts in the order Ru/KL > RuCu0.5/KL > RuCu1.0/KL > RuCu1.5/KL and strengthened by the CO-FTIR and microcalorimetry results.
J. Alvarez-Rodriguez, A. Guerrero-Ruiz, I. Rodriguez-Ramos, A. Arcoya-Martin, Microporous and Mesoporous Materials 97 (2006) 122-131

B1910 – Adhesion of solid particles to gas bubbles. Part 2: Experimental

In slurry bubble columns, the adhesion of solid catalyst particles to bubbles may significantly affect the G-L mass transfer and bubble size distribution. This feature may be exploited in design by modifying the hydrophilic or hydrophobic nature of the particles used. Previously we have proposed a generalised model, describing the adhesion of particles to G-L interface under stagnant conditions. In this work, we studied the adhesion of particles characterised by different degree of hydrophobicity and porosity: non-porous polystyrene and glass beads, unmodified and hydrophobised mesoporous silica, and activated carbon particles. Images recorded at high optical magnification show the particles adhering to gas bubbles individually or as aggregates. In aqueous media, higher liquid surface tension and particle surface hydrophobicity increase the adhesion strength and the tendency of particles to agglomerate, in agreement with the model. The adhesion of non-porous rough-surface particles to gas bubbles can be characterised by the receding contact angle. The advancing contact angle represents better the adhesion of the same particles to liquid droplets. We found that the "effective" contact angle of porous particles is much lower than an "intrinsic" contact angle calculated from the heat of immersion in water, or measured by sessile drop method. An equivalent contact angle derived from the Cassie rule explains the wetting behaviour of particles having the pores filled with liquid.
F. Omota, A.C. Dimian, A. Bliek, Chemical Engineering Science 61 (2006) 835 - 844

B1901 – Competition of FAU and LTA in the synthesis system (TMA,Na)2O-Al2O3-SiO2-H2O

Eight initially clear solutions (with a general formula based on molar ratios of the components, xNaOH:(5.86 x)TMAOH:1.0- Al2O3:3.40SiO2:370H2O:19.6EtOH:6.0iso-PrOH, x = 0.06-0.86) with various sodium concentrations were prepared for synthesis of FAU/LTA zeolites at 98.0 C. The synthesis process was studied using in situ calorimetry and the solid products were characterized using XRD, SEM and TG-DSC. At low sodium concentration (x = 0.06), the product is nearly pure FAU while with increasing x from 0.06 to 0.86, LTA gradually becomes dominant. In addition, the sodium concentration has a strong influence on crystal size but limited influence on the chemical composition of the resulting zeolite(s). At x = 0.86, the conversion yields of both silica and alumina are about 50%. When x decreases from 0.86 to 0.06, both conversion yields rapidly decrease to only about 4%. In contrast, the conversion yield of sodium remains at a much higher level (75-100%). There appears to be a maximum crystallization rate at x = 0.16-0.26. Crystallization of both FAU and LTA zeolites is exothermic and the crystallization enthalpy for FAU is higher in magnitude than for LTA.
S. Yang, Q. Li, M. Wang, A. Navrotsky, Microporous and Mesoporous Materials 87 (2006) 261-267

B1900 – Characterisation of Al-rich microporous micelle-templated silicates. Part II: Spectroscopic and microcalorimetric study of the accessibility of exchanged alkali-cations to carbon dioxide

Two micelle-templated materials with Si/Al ratio = 2.5, exchanged at 43% with Li+ ions and at 82% with Na+ ions, respectively, have been characterized by means of CO2 adsorption followed by FT-IR spectroscopy and microcalorimetry, their texture and acidic properties having been studied in a previous paper [B. Bonelli, B. Onida, J.D. Chen, A. Galarneau, F. Di Renzo, F. Fajula, E. Garrone, Micropor. Mesopor. Mater. 67 (2004) 95]. CO2 adsorption shows that no strong basic sites (oxygen anions able to form carbonate-like species) occur at the surface, in contrast to findings with zeolites of comparable composition. CO2 interacts instead in a linear form with Lewis acidic sites, and reveals that only a part of Na or Li sites are accessible to the probe. The amorphous nature of the walls allows exchangeable alkali-cations to be partially "sunk" among surrounding oxygen anions: the majority of Na+ ions are not accessible to CO2, whereas only about one half of Li+ ions are so. A dramatic decrease in the differential heats of adsorption with coverage indicates that interaction with the CO2 ligand probably implies some extraction of the cations from the amorphous matrix. Na cations only form 1:1 adducts with CO2, whereas Li cations may form 1:2 species.
B. Bonelli, B. Onida, J.D. Chen, A. Galarneau, F. Di Renzo, F. Fajula, B. Fubini, E. Garrone, Microporous and Mesoporous Materials 87 (2006) 170-176

B1896 – Nanosized iron and iron-cobalt spinel oxides as catalysts for methanol decomposition

Nanosized iron and mixed iron-cobalt oxides supported on activated carbon materials and their bulk analogues prepared by thermal synthesis are studied by X-rays diffraction, Mo¨ssbauer spectroscopy, magnetic measurements and temperature programmed reduction. Their catalytic behavior in methanol decomposition to H2, CO and methane is tested. Phase transformations in the metal oxides affected by the reaction medium are also investigated. Changes in the reaction mechanism of the methanol decomposition after the metal oxides deposition on the support as compared to the bulk phases are discussed.
E. Manova, T. Tsoncheva, Cl. Estournès, D. Paneva, K. Tenchev, I. Mitov, L. Petrov, Applied Catalysis A: General 300 (2006) 170-180

B1890 – Investigation of the water sorption properties of Mars-relevant micro- and mesoporous minerals

Encouraged by recent results of the Mars Odyssey spacecraft mission and the OMEGA team (Mars Express) concerning water in equatorial latitudes between ±45° on Mars and the possible existence of hydrated minerals, we have investigated the water sorption properties of natural zeolites and clay minerals close to martian atmospheric surface conditions as well as the properties of Mg-sulfates and gypsum. To quantify the stability of hydrous minerals on the martian surface and their interaction with the martian atmosphere, the water adsorption and desorption properties of nontronite, montmorillonite, chabazite and clinoptilolite have been investigated using adsorption isotherms at low equilibrium water vapor pressures and temperatures, modeling of the adsorption equilibrium data, thermogravimetry (TG), differential scanning calorimetry (DSC), and proton magic angle spinning nuclear magnetic resonance measurements (1H MAS NMR). Mg-sulfate hydrates were also analyzed using TG/DSC methods to compare with clay mineral and zeolites. Our data show that these microporous minerals can remain hydrated under present martian atmospheric conditions and hold up to 2.5-25 wt% of water in their void volumes at a partial water vapor pressure of 0.001 mbar in a temperature range of 333-193 K. Results of the 1H MAS NMR measurements suggest that parts of the adsorbed water are liquid-like water and that the mobility of the adsorbed water might be of importance for adsorption-water-triggered chemistry and hypothetical exobiological activity on Mars.
J. Jänchen, D.L. Bish, D.T.F. Möhlmann, H. Stach, Icarus 180 (2006) 353-358

B1887 – FT-IR study of CO and NO adsorption on a VSiBEA zeolite

A VSiBEA zeolite containing 2.1 wt.% V has been prepared by a two-step post-synthesis method, which consists of first creating vacant T-sites by dealumination of the BEA zeolite with nitric acid and then impregnation of the SiBEA zeolite with an aqueous solution of ammonium metavanadate (NH4VO3), used as V5+ precursor. The sample has been studied by XRD analysis, FT-IR, TPR and diffuse reflectance UV-Visible spectroscopy. The disappearance of the IR band near 3520 cm 1 after impregnation of NH4VO3 indicates that a specific reaction has occurred between the vanadium precursor and silanol groups of vacant T-sites. As a result, tetrahedral V5+ ions connected with OH groups are incorporated in the framework. In addition, weakly bound extraframework V5+ species (tetrahedral and octahedral) exists. CO and NO were used as IR probes for establishing the state of reduced vanadium sites. It was found that NO was a better probe for this purpose, but CO provided valuable complementary information on the coordination state of the reduced vanadium sites. As expected, adsorption of both, CO and NO, was negligible on non-reduced sample. However, sample reduced with hydrogen at 673 K is characterised by a high concentration of V4+ and V3+ sites produced by the reduction of the extraframework sites. NO was found to form dinitrosyls with both V4+ and V3+ cations. The V4+(NO)2 species are characterised by ms at 1902 cm 1 and mas at 1755 cm 1. The dinitrosyls of V3+ were registered at 1830 (ms) and 1687 cm 1 (mas). Reduction at 773 K led to increase in amount of the V3+ species and formation of framework V4+ cations (respective dinitrosyl bands at 1900 and 1729 cm 1). The spectra of CO adsorbed on the reduced sample are complex. Evidence of tricarbonyl species was found. It was concluded that CO is a better probe than NO for testing the coordination state of V4+ and V3+ sites.
E. Ivanova, K. Hadjiivanov, S. Dzwigaj, M. Che, Microporous and Mesoporous Materials 89 (2006) 69-77

B1876 – Structural, redox and acid-base properties of V2O5/CeO2 catalysts

CeO2 supported V2O5 catalysts were prepared by the wetness impregnation technique and their surface structures were characterized by O2 chemisorption, X-ray diffraction (XRD) and Raman spectroscopy (LRS). The surface acidity and basicity were measured by using microcalorimetry and infrared spectroscopy (FTIR) for the adsorption of NH3 and CO2. Temperature programmed reduction (TPR) was employed for the redox properties. In particular, isopropanol probe reactions with and without the presence of O2 were employed to provide the additional information about the surface acidity and redox properties of the catalysts. Variation of loading of V2O5 and calcination temperature brought about the changes of surface structures of dispersed vanadium species, and hence the surface acidic and redox properties. Structural characterizations indicated that V2O5 can be well dispersed on the surface of CeO2. The monolayer dispersion capacity was found to be about 8 V/nm2, corresponding to about 10% V2O5 by weight in a V2O5/CeO2 sample with the surface area of 80m2/g. Vanadium species in the catalysts (673K calcined) with loading lower than 10% were highly dispersed and exhibited strong surface acidity and redox ability, while higher loading resulted in the formation of significant amount of surface crystalline V2O5, which showed fairly strong surface acidity and significantly weakened redox ability. Calcination of a 10% V2O5/CeO2 at 873K resulted in the formation of mainly CeVO4 on the surface, which showed low surface acidity and redox ability. The probe reaction seemed to suggest that the calcination at higher temperature might cause the decrease of surface acidity more than redox ability. Thus, the 10% V2O5/CeO2 catalyst calcined at 873K exhibited much higher selectivity to benzaldehyde as compared to other V2O5/CeO2 catalysts studied in this work, although its activity for the conversion of toluene was relatively low.
X. Gu, J. Ge, H. Zhang, A. Auroux, J. Shen, Thermochimica Acta 451 (2006) 84-93

B1859 – Pillared laponite clays-supported palladium catalysts for the complete oxidation of benzene

Zr-, Ce-, and Al-pillared laponite clays (Al-Lap, Ce-Lap, Zr-Lap) were prepared and used as supports of palladium catalysts for the complete oxidation of benzene. The pillared clays and the supported Pd catalysts were characterized by N2 adsorption/desorption, differential scanning calorimetry (DSC), hydrogen chemisorption and temperature-programmed reduction (TPR) techniques. The specific surface areas of the pillared clays exceed 430m2/g, and the pore diameters are greater than 4 nm. DSC analysis revealed that the pillared clays have higher thermal stability in comparison with the parent clay. Palladium catalysts supported on the pillared clays are much more active than those supported on conventional alumina. Pd/Zr-Lap, in particular, could catalyze the complete oxidation of benzene at a temperature as low as 210°C. The effect of calcination temperature on the catalytic activity was investigated. The optimal calcination temperature was found to be 400°C for Pd/Al-Lap catalysts, and 600°C for Pd/Zr-Lap and Pd/Ce-Lap catalysts. At optimal calcination temperatures, palladium crystallites of proper size could be formed in pillared clays and showed a higher activity than those calcined at other temperatures.
J. Li, Z. Jiang, Z. Hao, X. Xu, Y. Zhuang, Journal of Molecular Catalysis A: Chemical 225 (2005) 173-179

B1857 – Ruthenium-supported catalysts for the stereoselective hydrogenation of paracetamol to 4-trans-acetamidocyclohexanol: effect of support, metal precursor, and solvent

The influence of the support, the metal precursor, and the solvent on the selective hydrogenation of paracetamol (4-acetamidophenol) was studied over supported ruthenium catalysts. The catalysts supported on the oxidic supports Al2O3 and SiO2 gave the best results in terms of activity, selectivity for the acetamidocyclohexanols (99%), and stereoselectivity for the trans isomer (53 and 46%, respectively). Carbon-supported catalysts produced larger amounts of secondary compounds, mainly N-cyclohexylacetamide, which was derived from the hydrogenolysis reaction of the OH group. The use of a chloride precursor resulted in the enhancement of the formation of Ncyclohexylacetamide and partially hydrogenated products; the stereoselectivity also increased. Moreover, because of the acidity caused by residual Cl, condensation led to oligomers of paracetamol. In spite of the decrease in the selectivity for cyclohexanol derivatives when the more polar solvent ethanol was used instead of isopropanol or tetrahydrofuran the stereoselectivity for the trans isomer increased from 30 to 38%. The results confirm that the factors studied affect the mode of adsorption of the molecule of paracetamol on the catalyst in different ways. These effects determine the product distribution and the selectivity of the reaction.
B. Bachiller-Baeza, A. Guerrero-Ruiz, I. Rodriguez-Ramos, Journal of Catalysis 229 (2005) 439-445

B1856 – Carbon molecular sieve cloths prepared by chemical vapour deposition of methane for separation of gas mixtures

Microporous carbon molecular sieves for separating gaseous mixtures have been prepared through chemical vapour deposition (CVD) of methane on activated carbon cloth obtained from Nomex aramid fibre. The activated carbon fibres were subjected to CVD of methane for different periods of time. The textural characterization of the resulting materials was assessed by physical adsorption of gases (N2 and CO2) and vapours (dichloromethane, benzene and cyclohexane) as well as immersion calorimetry into the same liquids. A direct visualization of the changes induced by CVD on the micropore mouth structure of the activated carbon cloth was provided by scanning tunnelling microscopy (STM). The validity of the materials for separating CO2/CH4 and O2/N2 was tested by assessing the kinetics of adsorption of the corresponding gases. Carbon molecular sieves with good selectivity for CO2/CH4 separation and showing acceptable CO2 adsorption capacity were obtained.
S. Villar-Rodil, R. Navarrete, R. Denoyel, A. Albiniak, J.I. Paredes, A. Martinez-Alonso, J.M.D. Tascon, Microporous and Mesoporous Materials 77 (2005) 109-118

B1843 – Interaction between sulfated zirconia and alkanes: prerequisites for active sites-formation and stability of reaction intermediates

Two sulfated zirconia catalysts were prepared via sulfation and calcination of zirconium hydroxide at 873 K; the zirconium hydroxide had been aged at room temperature for 1 h (SZ-1) or aged at 373 K for 24 h (SZ-2). SZ-1 was active for n-butane isomerization at 373 K; SZ-2 reached a similar performance level only at 473 K. Both materials contained about 9 wt% sulfate and were tetragonal. Because of a lower BET surface area (105 vs. 148 m2/g) SZ-1 featured a higher sulfate density, and XRD and EXAFS analysis showed larger (ca. 10 nm) and more well ordered crystals than for SZ-2. n-Butane TPD on SZ-1 showed a butene desorption peak at low temperature, whereas no obvious butene desorption was observed with SZ-2, suggesting that SZ-1 has a higher oxidizing power at low temperature than SZ-2. The number of sites capable of dehydrogenation are less than 5 µmol/g, because the differential heats of n-butane adsorption as measured by microcalorimetry were 45-60 kJ/mol for higher coverages, indicating weak and reversible interaction. TAP experiments describe the adsorption and desorption behavior of n-butane at different activity states and are the basis for a simple adsorption model. Reactant pulses and purge experiments show that the active species, presumably formed in an oxidative dehydrogenation step, are stable at the surface under reaction conditions.
X. Li, K. Nagaoka, L.J. Simon, J.A. Lercher, S. Wrabetz, F.C. Jentoft, C. Breitkopf, S. Matysik, H. Papp, Journal of Catalysis 230 (2005) 214-225

B1835 – Dichloromethane transformation over bifunctional PtFAU catalysts. Influence of the acidobasicity of the zeolite

The catalytic oxidation of dichloromethane (DCM) was investigated over PtNaX and PtNaY catalysts with different amounts and dispersions of Pt under the following conditions: fixed bed reactor, 1000 ppm of DCMin wet air, space velocity of 20,000 h-1, temperature between 220 and 450°C. It is shown that Pt has only a limited effect on DCM conversion but causes a significant change in the product composition; the only role of Pt is to oxidise formaldehyde resulting from DCM hydrolysis on the zeolite support. DCM hydrolysis was carried out over a series of FAU zeolites: NaX, LiY, NaY, KY, CsY and USHY. The hydrolysis rate was shown to increase significantly with the zeolite basicity. A general reaction mechanism is proposed involving mainly the transformation of DCM species adsorbed on acido (H+, alcaline cation) basic (zeolite, framework oxygens) sites into chloromethoxy then hydroxymethoxy species.
L. Pinard, J. Mijoin, P. Magnoux, M. Guisnet, C. R. Chimie 8 (2005) 457-46

B1834 – Liquid-phase alkylation of phenol with t-butanol over various catalysts derived fromMWW-type precursors

Three types of MWW-based catalysts (MCM-22, MCM-36 and ITQ-2) were studied in the liquid-phase alkylation of phenol by tert-butanol (TBA). Ammonia adsorption calorimetry was applied to investigate the acid properties of zeolites with different framework topology and crystallinity. It was established that acid properties of MCM-22 family depend mainly of the solid Al-content (the Si/Al ratio varied from 9.1 to 46.0). Delamination of MCM-22 precursor (MCM-22(P)) leading to ITQ-2 results in the decrease of the total acidity and the increase of the intermediate acid sites concentration, while the pillaring process yielding MCM-36 affected mainly the total concentration of acid sites, the acid strength distribution being similar to the corresponding MCM-22 zeolite. The catalytic activity and selectivity of zeolite-based catalysts are discussed. The most active catalyst for the studied reaction was MCM-22 B (Si/Al ~ 15). The results obtained with MCM-22 as catalyst revealed that, despite the expectations due to the presence of 10-MR pores in the structure of this zeolite, no enhanced selectivity to p-tert-butyl phenol (p-TBP) is observed. This has been rationalized by the assumption that most of reactions occurring in this system take place on acid sites at or close to the external surface. This assumption is also supported by the similar catalytic selectivity of the MWWderived structures (viz. MCM-36 and ITQ-2), which expose a higher concentration of external pockets. However, it is noticeable the high catalytic activity of MCM-22 zeolites for the liquid-phase alkylation of phenol by TBA that is comparable to the gas-phase activity of large pore zeolites like as HY or HM.
E. Dumitriu, D. Meloni, R. Monaci, V. Solinas, C. R. Chimie 8 (2005) 441-456

B1831 – Synthesis and structural analyses of poly (1, 2-cyclohexene oxide) over solid acid catalyst

The polymerization of 1, 2-cyclohexene oxide was carried out at 20°Cin dichloromethane with an acid-exchanged montmorillonite as acid solid catalyst. The effect of the amount of catalyst, solvent, and temperature was studied. A typical reaction product (PCHO) was analyzed by infrared and nuclear magnetic resonance spectroscopy, as well as by gel-permeation chromatography and MALDI-TOF MS, Xray diffraction, and differential scanning calorimetry (DSC). The X-ray and DSC data show that PCHO is an amorphous substance. The mechanism of the polymerization appears to be cationic.
A. Yahiaoui, M. Belbachir, J.C. Soutif, Laurent Fontaine, Materials Letters 59 (2005) 759-767

B1825 – Sn-modified Ni catalysts for aqueous-phase reforming: Characterization and deactivation studies

The catalytic deactivation of R-NiSn catalysts was explored during hydrogen production by aqueous-phase reforming (APR) of ethylene glycol. X-ray photoelectron spectroscopy and CO and H2 adsorption microcalorimetry were combined with previous characterization to show that R-NiSn catalysts are composed of a Ni core surrounded by a Ni3Sn alloy after heat treatments above 533 K. Adsorption studies (CO, H2, and N2), XPS, X-ray diffraction, and thermogravimetric analysis show that R-Ni15Sn catalysts deactivate by interaction with water under APR reaction conditions, rather than coking or Ni(CO)4 formation. Over the first 48 h on stream, deactivation proceeds rapidly by the sintering of small Ni particles and by the formation of NiSn surface alloys with lower catalytic activity and higher selectivity for the production of hydrogen by APR of dilute feed solutions. After several days on stream, R-Ni15Sn catalysts deactivate at a slower rate because of oxidation and dissolution by water, leading to Ni effluent concentrations near 50 wppm after 240 h on stream. The first-order deactivation constant can be improved from kd = 0.0020 h-1 to less than 0.0001 h-1 between 140 and 240 h on stream with the use of rigorous heat treatments at 623 K in H2 to form resilient NiSn alloys prior to reaction and/or with the use of energy-efficient stoichiometric feeds (water/ethylene glycol = 2).
J.W. Shabaker, D.A. Simonetti, R.D. Cortright, J.A. Dumesic, Journal of Catalysis 231 (2005) 67-76

B1823 – Liquid-phase oxidation of alcohols by oxygen and nitrous oxide catalysed by Ru-Co oxide

Chemoselective catalysts in bulk or supported on y -Al2O3 binary oxides RuIV-CoIII (Ru/Co = 1:1-1:2), prepared by co-precipitation, were used for liquid-phase oxidation of saturated and unsaturated primary and secondary alcohols to aldehydes and ketones with O2 or N2O. The catalysts can be separated by filtration and reused. No leaching of Ru or Co in solution was observed. The oxidation is enhanced by the presence of hydration water in the Ru-Co catalyst, which indicates the participation of active RuIV hydroxo species in the reaction. From XRD and TGA, the Ru-Co oxide can be approximated as a hydrous binary oxide comprising the amorphous RuO2 and heterogenite- 3R cobaltic acid CoO(OH). The alcohol oxidation appears to occur by a nonradical mechanism, which may be viewed as an oxidative dehydrogenation of alcohols to form an aldehyde or ketone. H2-TPR shows that CoIII practically does not affect the oxidising ability of RuO2. This suggests that the cobalt is likely to enhance catalyst reoxidation by O2 rather than to play a significant role in the alcohol dehydrogenation. The alcohol oxidation by N2O exhibits a close similarity to the oxidation by O2 but is much less efficient. Much more active catalysts are required to make the oxidation with N2O synthetically useful.
T.L. Stuchinskaya, M. Musawir, E.F. Kozhevnikova, I.V. Kozhevnikov, Journal of Catalysis 231 (2005) 41-47

B1819 – Effect of the metal precursor on the surface site distribution of Al2O3-supported Ru catalysts: catalytic effects on the n-butane/H2 test

Several alumina-supported Ru catalysts prepared from different metal precursors were comparatively studied by H2 and CO adsorption microcalorimetry and by Fourier transformed-infrared spectroscopy (FT-IR) of the chemisorbed CO molecule. The correlation of the results thus obtained from these techniques with those on the n-butane/H2 reaction test, provides useful information about the type and distribution of the surface active sites on the supported metal crystallites. Also, the comparison of the results obtained from these complementary techniques with those reported for monocrystals or from other studies available in the scientific literature for supported Ru catalysts, enables the tentative attribution of the type of exposed crystalline planes. In this way, the energetic distribution of surface sites has been shown to depend on the mean metal particle size as well as on the Ru precursor involved in the preparation.
A. Maroto-Valiente, M. Cerro-Alarcon, A. Guerrero-Ruiz, I. Rodriguez-Ramos, Applied Catalysis A: General 283 (2005) 23-32

B1810 – CO adsorption on highly dispersed MoP/Al2O3 prepared with citric acid

Calorimetry of CO adsorption was used for the first time to study the surface properties of alumina-supported molybdenum phosphide (MoP/Al2O3). To increase the dispersion of MoP active sites, the sample was prepared by novel citric acid-temperature programmed reduction (CA-TPR) method. Fourier transform infrared spectroscopy (FT-IR) of CO adsorption confirmed the formation of MoP by CA-TPR method. The calorimetry results proved that the novel method increased the amounts of active sites and led to the formation of a highly dispersed aluminasupported MoP, but the adsorption heat and the active sites distribution were not much affected by the preparation method. Furthermore, the energetic distribution of active sites depended on the MoP loading.
R. Cheng, Y. Shu, L. Li, J. Sun, X. Wang, T. Zhang, Thermochimica Acta 450 (2006) 42-46

B1793 – Synthesis and characterization of Zn/Al and Pt/Zn/Al layered double hydroxides obtained by the sol-gel method

The influence of the nature of the Zn, Al and Pt precursors, and of the temperature of precipitation and aging have been studied in connection with the preparation of Zn/Al and Pt/Zn/Al layered double hydroxides (LDH) by the sol-gel method. Whatever the precursors the XRD analysis shows that LDH is formed at the expense of ZnO when the precipitation and aging temperatures decrease from 353 K to 273 K. Moreover, chemical composition and TG analysis suggest the presence of weak amounts of hydrozincite, hydrozincite-like and Al(OH)3 phases. When the precursors are Zn acetate-2-hydrate or Al acetylacetonate the amount of LDH reaches a maximum of 50 mol% at 273 K. At variance, about 90 mol% of LDH is obtained when using Zn acetylacetonate and Al isopropoxide as precursors, which are precipitated at 273 K. This proportion is slightly improved for the Pt-containing sample prepared under the same conditions. The specific surface areas of the different samples obtained after calcination at 723 K increase with their LDH content, reaching values of 110-120 m2 g 1. They make them particularly attractive for catalytic applications.
D. Tichit, O. Lorret, B. Coq, F. Prinetto, G. Ghiotti, Microporous and Mesoporous Materials 80 (2005) 213-220

B1778 – Synthesis, characterization and performance evaluation of Ni/Al2O3 catalysts for reforming of crude ethanol for hydrogen production

The effects of catalyst synthesis method (i.e. precipitation (PT), coprecipitation (CP) and impregnation (IM)), Ni loading and reduction temperature on the characteristics and performance of Ni/Al2O3 catalysts were evaluated for the reforming of crude ethanol for H2 production. The results showed that in the calcined PT catalysts, no NiAl2O4 species were observed whereas this was a major species in CP and IM catalysts. As a result, PT catalysts were more reducible than CP and IM catalysts. PT catalysts exhibited slightly lower crystallite sizes of NiO species than the corresponding CP catalysts. On the other hand, IM catalysts had extremely large crystallite sizes except IM10 (IM catalyst with 10% Ni loading) which had the smallest crystallite size. A combination of small crystallite size and high reducibility for PT catalysts resulted in higher crude ethanol conversions for the PT catalysts. In contrast, the IM catalysts with larger crystallite sizes and lower reducibility yielded the lowest crude ethanol conversions. Catalysts with 15% Ni loading gave the best crude ethanol conversions for each method of synthesis with PT15 giving the best overall crude ethanol conversion of 85 mol% again because of its smaller crystallite size and higher reducibility. In terms of H2 yield, CP15 was the optimum catalyst because of its higher H2 selectivity as compared to PT15 and IM15 catalysts. Coking was observed at the onset of the reaction but stabilized after 180 min TOS.
A.J. Akande, R.O. Idem, A.K. Dalai, Applied Catalysis A: General 287 (2005) 159-175

B1769 – Addition of hydrogen sulfide to methyl acrylate over solid basic catalysts

H2S was added to methyl acrylate in a batch reactor at 313 K, 450 rpm, 0.2 M (in decane) in methyl acrylate, 5.5 bar of hydrogen sulfide pressure in the presence of solid bases. The bases differed in their chemical composition, structural properties, and acid-base properties. The bases were cation-exchanged X-faujasites, magnesium oxide, alkaline- and alkaline-earth-doped magnesium oxides, and commercially available and synthesized mixed magnesium/aluminum oxides. All of these catalysts were shown to achieve, in terms of both activity and selectivity, the addition of H2S to methyl acrylate as compared with the patent literature. Catalytic runs have also been conducted on a fixed-bed continuous-flow reactor with performances, in terms of selectivity, better than those observed in batch mode, particularly with a Cs-exchanged X zeolite, which featured a selectivity level similar to that of modified ion-exchange resins. As previously assumed from kinetics and IR studies on H2S and methyl acrylate adsorption and co-adsorption, the prerequisite for the title reaction to occur is the dissociation of H2S into HS- and H+ species over weak acid/strong basic Lewis pair sites. This assumption is confirmed in this work and is in agreement with the HSAB principle; H2S is dissociated into a soft HS- nucleophilic species associated with a soft Mx+ acid, and the hard H+ species is associated with the hard O2- basic species.
E. Breysse, F. Fajula, A. Finiels, G. Frémy, D. Tichit, C. Moreau, Journal of Catalysis 233 (2005) 288-296

B1766 – Boron nitride: A high potential support for combustion catalysts

High surface area BN powders have been prepared from different precursors to be used as supports for noble metal catalysts. The more suitable boron nitride powders were obtained using polytrichoroborazine, pTCB, as precursor, leading to a surface area higher than 150m2/g. The BN powders were characterized by XRD, XPS, TG, SEM and adsorption microcalorimetry measurements (aniline and ammonia). The preliminary results showed a remarkable stability of the BN supports, even in the presence of moisture. Palladium impregnation of the BN powders was performed using a classical method and the obtained catalysts exhibited a high dispersion with Pd particles of about 4 nm.
G. Postole, M. Caldararu, N.I. Ionescu, B. Bonnetot, A. Auroux, C. Guimond, Thermochimica Acta 434 (2005) 150-157

B1765 – Microcalorimetry, TPR and XPS studies of acid-base properties of NiCuMgAl mixed oxides using LDHs as precursors

NiCuMgAl layered double hydroxides (LDHs) with hydrotalcite-like structure containing different proportions of Ni2+, Cu2+, Mg2+ and Al3+ cations have been prepared. Thermogravimetry and X-ray diffraction data indicate that the transformation of LDH into mixed oxides is effective after calcination at 450°C. The acid-base properties of these mixed oxides have been investigated using adsorption microcalorimetry and X-ray photoelectron spectroscopy with SO2 (for basicity) and NH3 (for acidity) as probe molecules. The basicity depends principally on the Ni/Cu ratio and increases with the Ni proportion. The strength (strong and medium) of the basic sites is particularly homogeneous. On the surface of the oxides, they are both Bronsted (-60%) and Lewis sites (-40%). The acidity (only Lewis type) is rather weak and dependant, as the basicity, of the Ni/Cu ratio. The observed heterogeneity of these sites can be related to the heterogeneity of the interactions between the nickel atoms and the other elements.
L. Dussault, J.C. Dupin, E. Dumitriu, A. Auroux, C. Guimon, Thermochimica Acta 434 (2005) 93-99

B1763 – Influence of cations on active sites of the alkaline earth salts of 12-tungstophosphoric acid: microcalorimetric study

The acidic properties of the alkaline earth salts of 12-tungstophosphoric acid were investigated using ammonia absorption microcalorimetry. The number and the strength of acid sites of these catalysts as well as differential heats of ammonia absorption were determined. As a result of substitution of two protons with one alkaline earth cation, the decrease of both the total number of acid sites and the number of the strongest acid sites characterized by differential heats higher then 150 kJ/mol, compared to the values found in the case of initial 12-tungstophosphoric acid, were noticed. While all protons seem accessible for ammonia in Mg, Ca and Ba salts, in the case of Sr salt less then stoichiometric ammonia sorption was detected which can be explained by steric effect of these divalent cations.
Lj. Damjanovic, V. Rakic, U.B. Mioc, A. Auroux, Thermochimica Acta 434 (2005) 81-87

B1762 – Application of calcined Mg-Al hydrotalcites for Michael additions: an investigation of catalytic activity and acid-base properties

Mg-Al hydrotalcite catalysts with different Mg/Al molar ratios (0.6, 1.4, 2.2, 3.0) were calcined and tested in liquid-phase Michael additions at room temperature. The catalysts and pure oxides (MgO and Al2O3) were characterized by XRD, XPS, N2 adsorption experiments, 27Al MAS NMR, and TG-DTA. The acid-base properties of the samples were investigated by (a) FTIR spectroscopy after pyridine and CO2 adsorption and (b) microcalorimetry with CO2 and benzoic acid. Both acid sites (Lewis) and base sites (Lewis and Bronsted) are present on the surface of calcined hydrotalcites. The calcined hydrotalcites (CHT) catalyzed the Michael additions of CH-acid compounds to methyl vinyl ketone to give high product yields with 100% selectivity; the Al-rich sample exhibited the highest activity.
H.A. Prescott, Z-J. Li, E. Kemnitz, A. Trunschke, J. Deutsch, H. Lieske, A. Auroux, Journal of Catalysis 234 (2005) 119-130

B1761 – Preparation, characterisation and activity of chromia-zirconia catalysts for propane dehydrogenation

Dehydrogenation catalysts based on chromia supported on ZrO2, containing about 10 wt.% of chromium and increasing amounts of potassium (up to 4 wt.%), were prepared and characterised by chemical analysis, N2 adsorption-desorption at 77 K, X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (DRS), temperature programmed reduction (TPR) and adsorption microcalorimetry of ammonia. IncreasingKamounts deeply modify the ammonia adsorption behaviour, with a progressive decrease in the acidic features, which are completely lost when the K content attains 1 wt.%. Reduction of Cr species seems rather easy for chromia-zirconia and K-containing chromia-zirconia samples with K contents up to 0.5 wt.%. The onset of reduction shifts to higher temperatures as the K concentration increases. Catalytic testing was performed under atmospheric pressure at 813 K. Pure zirconia is very poorly active in propane dehydrogenation; also virtually inactive are the samples with a K content >1 wt.%. Conversion decreases as the K amount increases up to 0.5 wt.%, propene selectivity being close to 100 mol%. An induction period is observed for all the active samples, which attains a maximum in conversion before being deactivated by coking
M.G. Cutrufello, S. De Rossi, I. Ferino, R. Monaci, E. Rombi, V. Solinas, Thermochimica Acta 434 (2005) 62-68

B1744 – Study of the influence of the In2O3 loading on y -alumina for the development of de-NOx catalysts

Alumina-supported indium oxide (In2O3) catalysts with In loadings between 2 and 22 wt% were prepared by impregnation and characterized for their main properties. Surface properties, such as the surface area; surface In content, measured by X-ray photoelectron spectroscopy (XPS); and acidity and basicity, measured both by adsorption microcalorimetry using ammonia and sulfur dioxide as probe molecules and by infrared spectroscopy of pyridine adsorption, were determined. Bulk properties, namely the crystallographic structure as determined by powder X-ray diffraction (XRD) analysis and the redox character of the In2O3-dispersed phase as determined by redox cycles performed both in a flow apparatus and in a thermobalance coupled with a differential scanning microcalorimeter (TG-DSC), were studied. The results obtained were interpreted in terms of In2O3 surface dispersion or aggregation. The catalysts tested in the reduction of NOx by ethene in an oxygen-rich atmosphere showed an interesting ability to selectively reduce NOx to N2, independently of the In loading. The weakness of the oxidative properties of the In2O3 phases limited the ethene combustion and made the catalysts able to reduce NOx even at high temperature (up to 550.C). The rates of nitrogen formation depended strongly on the In2O3 aggregation state; the In centers were very active even at low amounts.
J.A. Perdigon-Melon, A. Gervasini, A. Auroux, Journal of Catalysis 234 (2005) 421-430

B1743 – Modification of the catalytic behaviour of platinum by zinc in crotonaldehyde hydrogenation and iso-butane dehydrogenation

The effect of the presence of zinc on the catalytic behaviour of platinum in the vapour phase hydrogenation of crotonaldehyde (2-butenal) and in iso-butane dehydrogenation has been determined in activated carbon-supported catalysts prepared using H2PtCl6 and Zn(NO3)2 as the metal precursors. The catalysts have been characterised by temperature-programmed reduction (TPR), adsorption microcalorimetry of CO at room temperature and X-ray photoelectron spectroscopy after in situ reduction at 773 K. The bimetallic catalyst, with a bulk Zn/Pt atomic ratio of 13.7, showed a much higher initial activity in crotonaldehyde hydrogenation, although it deactivated more strongly with time on stream. Lower activation energy for this reaction was also obtained, as well as a higher selectivity towards the unsaturated alcohol. On the other hand, the catalytic behaviour for iso-butane dehydrogenation was greatly improved by the presence of zinc, the bimetallic catalyst being more active than its monometallic counterpart and showing 100% selectivity to iso-butene.
J. Silvestre-Albero, J.C. Serrano-Ruiz, A. Sepulveda-Escribano, F. Rodriguez-Reinoso, Applied Catalysis A: General 292 (2005) 244-251

B1736 – Partially hydrophobized silica supported Pd catalyst for hydrogenation reactions in aqueous media

The hydrophobic or hydrophilic nature of catalyst support materials may influence the reaction behaviour in three-phase catalytic oxidation or hydrogenation reactions in aqueous media. This may be attributed to the segregation or agglomeration behaviour of such support materials in water. We have systematically investigated the impact of surface hydrophobicity of silica supports during the catalytic hydrogenation of methyl acrylate in water. To this end, we deliberately varied the hydrophobicity of silica supported Pd catalysts by moderate silylation with dichlorodimethylsilane (DDMS). A range of materials was prepared in this way, with three-phase contact angles up to 908, in order to allow the water to fill the catalyst pores. Hydrophobic silica supported catalysts were either prepared by silylation of hydrophilic mesoporous silica followed by incipient wetness impregnation of the support with H2PdCl4 solution (a), or by the reverse procedure (b). This way of rendering the support more hydrophobic leads to an increased three-phase contact angle, lower heat of immersion in water and lower heat of water vapour adsorption. These factors induce a more pronounced adhesion of particles to gas bubbles. During the hydrogenation of methyl acrylate in aqueous media, hydrophobic Pd/silica catalysts show higher activity than similar hydrophilic Pd/silica catalyst. The catalyst prepared by the route (a) shows the highest activity also as result of better Pd dispersion on the hydrophobic support.
F. Omota, A.C. Dimian, A. Bliek, Applied Catalysis A: General 294 (2005) 121-130

B1725 – Modifications of the citral hydrogenation selectivities over Ru/KL-zeolite catalysts induced by the metal precursors

Three Ru/KL-zeolite catalysts containing 2 wt% of Ru were prepared from Ru3(CO)12, RuNO(NO3)3 and Ru(C5H7O2)3 precursors. The samples named Ru(c)/KL, Ru(n)/KL and Ru(a)/KL were studied by temperature-programmed reduction (TPR), by microcalorimetry of CO adsorption, by volumetric hydrogen chemisorption, by X-ray diffraction (XRD) and also by infrared spectroscopy of the CO adsorbed species (CO-FTIR). The catalytic activities and selectivities were evaluated in the hydrogenation of citral at 323 K and 5 MPa, in a stirred batch reactor. Metal dispersion follows the order Ru(c)/KL > Ru(n)/KL > Ru(a)/KL. The CO-FTIR spectra show a set of different ruthenium species on the support, suggesting the presence of large metal particle outside the zeolite and small crystallites inside the channels, the latter being majority in the Ru(c)/KL sample. Hydrogenation activity per surface metal atom (TOF) was found to be independent on the metal dispersion and, consequently, on the precursor used. The selectivity towards unsaturated alcohols (geraniol + nerol) is in the order Ru(c)/ KL < Ru(a)/KL = Ru(n)/KL, while the citronellal selectivity is maximum over the Ru(c)/KL catalyst. This latter effect can be correlated to the special catalytic properties of the smaller Ru particles located inside the zeolite cavities.
J.A. lvarez-Rodriguez, A. Guerrero-Ruiz, I. Rodriguez-Ramos, A. Arcoya-Martin, Catalysis Today 107-108 (2005) 302-309

B1723 – Further insights into the Ru nanoparticles-carbon interactions and their role in the catalytic properties

Temperature-programmed reduction (TPR) and CO adsorption microcalorimetry along with the catalytic behaviour in the n-butane/H2 test reaction were performed in order to determine the specific interactions of Ru nanoparticles supported on different carbon materials. Aspects such as the porous structure and surface chemistry (presence and elimination of surface oxygen functional groups) of the carbon material, or the effect of the metal precursor (e.g. presence of residual chlorine) on the final metal dispersion and on the surface structure of the Ru nanoparticles have been studied. The results obtained confirmthat surface oxidation of the support along with the nature of the Ru precursor affects the distribution of the metal precursor over the support (and, consequently, the final ruthenium dispersion) and also the surface site distribution. Besides, elimination of the surface oxygen functional groups of the carbon material, during the reduction treatments of the fresh catalyst samples, leads to surface reconstructions on the Ru nanoparticles that seem to expose different crystallographic planes. The presence of residual chlorine leads to electron deficient Ru sites, and this modifies the CO chemisorption heats and affects the catalytic properties in the n-butane/hydrogen test.
M. Cerro-Alarcon, A. Maroto-Valiente, I. Rodriguez-Ramos, A. Guerrero-Ruiz, Carbon 43 (2005) 2711-2722

B1719 – Benzylation of benzene over Fe-modified ZSM-5 zeolites: Correlation between activity and adsorption properties

The performance of Fe-ZSM-5 catalysts (prepared by incipient wetness, 0.5-2.5% of Fe) for benzylation of benzene by benzyl chloride was studied in this work and explained in terms of their chemical and adsorption properties. Catalysts were characterised by ICP-MS, XPS, XRD, nitrogen physisorption and calorimetry (in order to determine their surface acidity). Adsorption properties of the catalysts (for the reactants and products) have been studied by inverse gas chromatography (IGC). Enthalpies of adsorption, dispersive energies of adsorption, and specific interaction were selected as parameters to characterise the interaction of benzene, benzyl chloride and diphenylmethane with the studied catalysts. Reaction experiments, carried out in an isothermal batch reactor, showed that increasing amounts of iron lead to more active catalyst, but less selective for the formation of diphenylmethane. Experimental data were modelled considering a serial-parallel scheme. Results reported in this paper, suggest that the reaction is controlled by the adsorption and activation of the benzyl chloride. The addition of iron to the ZSM-5 zeolite largely increases the interaction between this compound and the catalyst surface.
E. Diaz, S. Ordoñez, A. Vega, A. Auroux, J. Coca, Applied Catalysis A: General 295 (2005) 106-115

B1714 – Comparative study on the gas-phase adsorption of hexane over zeolites by calorimetry and inverse gas chromatography

The scope of this work is to carry out a systematic comparison of inverse gas chromatography (IGC) and microcalorimetry as tools for the study of the gas-phase adsorption of organic vapours (using hexane as model compound) on zeolitic materials (using different Mn, Co and Fe-exchanged NaX and CaA zeolites). Adsorption isotherms were recorded using both techniques in the temperature range of 150-250°C, being observed that the shape of the isotherms obtained with the dynamic (IGC) and static (microcalorimetry) techniques was surprisingly similar in the pressure range at which both techniques are applicable (low surface coverages). Concerning to the measurement of the strength of the adsorption, calorimetric data provide two parameters related to the adsorption enthalpy: the initial differential heat and the isosteric adsorption enthalpy. A great coincidence was found between the last one and the adsorption enthalpy determined by IGC (4-20% of difference, depending on the studied material). The behaviour of the initial differential heat depends strongly on the studied material, being in some cases closely related to the other two parameters and temperature-independent (in the case on Mn-exchanged zeolites), whereas for the Co-CaA and Fe-CaA zeolites, it is temperature-dependent, being not correlated with the other parameters in this case. The main conclusion of this work is that IGC is an attractive alternative to the static microcalorimetric data for obtaining information on the adsorption of organic compounds on microporous materials.
E. Diaz, S. Ordoñez, A. Auroux, Journal of Chromatography A 1095 (2005) 131-137

B1708 – Calorimetric insights into the synthesis of templated materials

Major recent advances: In situ calorimetric studies of zeolite synthesis have been performed under conditions where the growing templated zeolite remains in contact with its aqueous solution. Nanoparticles form first, then aggregate to form the zeolite. As surface area decreases, hydroxyl ions begin to desorb from the shrinking surface of the growing crystals, raising the pH, causing a shift from exothermic to endothermic enthalpy of reaction, and slowing the completion of synthesis.
A. Navrotsky, Current Opinion in Colloid & Interface Science 10 (2005) 195 - 202

B1702 – Competitive adsorption of N2O and CO on CuZSM-5, FeZSM-5, CoZSM-5 and bimetallic forms of ZSM-5 zeolite

The behavior of copper-, iron- and cobalt-exchanged ZSM-5 (Si/Al = 20) and bimetallic forms of the same zeolite was investigated with reference to the adsorption of N2O and CO at 303 K. The interactions of both gases with investigated zeolites have been s
V. Rakic, V. Raca, V. Dondur, A. Auroux, Catalysis Today 110 (2005) 272-280

B1679 – Role of reaction-medium water on the acidity deterioration of a HZSM-5 zeolite

The combined effect of both the water content in the reaction medium and the reaction temperature (in the 400-500°C range) on the acidity deterioration of a HZSM-5 zeolite catalyst in the methanol to olefins process has been studied. Accordingly, the catalyst has been used in reaction-regeneration cycles in an isothermal fixed-bed reactor. The nature of the acid sites has been measured by means of Fourier transform infrared of the pyridine adsorbed. Both the total acidity and the acid strength distribution of the sites have been determined by calorimetric measurements of differential scanning of adsorption of ammonia and temperature-programmed desorption of this base. The results are proof of the irreversible loss of acidity at 450°C for a water content in the feed above 50 wt %. Irreversible deactivation occurs at 500°C from low values of conversion, even when pure methanol is fed.
A.G. Gayubo, A.T. Aguayo, A. Atutxa, R. Prieto, and J. Bilbao, Ind. Eng. Chem. Res. 43 (2004) 5042-5048

B1651 – Synthesis and characterization of acidic properties of Al-HMS materials of varying Si/Al ratios

HMS and Al-HMS materials with Si/Al ratio in the range 5-45 were synthesized by neutral templating pathway. The as synthesized as well as calcined samples were examined for pore size distribution, surface area and XRD. These investigations confirmed the hexagonal mesoporous structure formation at all Si/Al ratios. The TGA measurements indicated that two types of template species interacting with Si or Al could be distinguished. The acidity and acid strength distribution studies using microcalorimetric NH3 adsorption indicated that the acidity increases with Al content in the mesoporous structure. The presence of Al in the structure creates a wide variety of acid sites of varying strengths. The heterogeneity of the sites also increases with Al content of the catalysts. The activities for cumene cracking reaction to test acidity of the materials supported the trend obtained from microcalorimetric NH3 adsorption results.
T. Chiranjeevi, G. Muthu Kumaran, J.K. Gupta and G. Murali Dhar, Thermochimica Acta 443 ( 25006) 87-92

B1644 – Calorimetric methods for catalytic investigations of novel catalysts based on metallized S-layer preparations

The contribution will show the first results from calorimetric screening of novel catalysts. Biotemplated platinum nanoclusters were prepared on the basis of S-layer-bacterial surface proteins-on different supports. Methods were contrived and examined, permitting both the investigation of catalytic bulk material, and the investigation of sensory interesting coatings. The calorimetric measurements were carried out using conventional calorimetric technique (DSC 111, firm SETARAM) and miniaturized calorimetric systems (integrated circuit calorimeter - IC-calorimeter and a sensor platform). The results of the calorimetric investigations to the selected model reactions (oxidation of hydrogen, carbon monoxide and propane) demonstrate the interesting characteristics of these new catalysts.
R. Hüttl, F. Ullrich, G. Wolf, A. Kirchner, M. Mertig and W. Pompe, Thermochimica Acta 440 (2006) 13-18

B1640 – Energetics of bulk and nano-akaganeite, beta-FeOOH: Enthalpy of formation, surface enthalpy, and enthalpy of water adsorption

Akaganeite, beta-FeOOH, is a commonly occurring ferric mineral in the environment and is a sorbent, ion exchanger, and catalyst. It is often fine-grained (nanophase) and frequently contains excess water. Its enthalpy of formation was studied by solution calorimetry in aqueous HCl. The enthalpy of water adsorption was studied by a new calorimetric technique combining a Calvet microcalorimeter and an automated gas dosing system, used for surface adsorption measurements. Akaganeite samples with surface areas of 30-280 m2/g were used. Sample characterization was performed by X-ray powder diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, Brunauer-Emmett-Teller method, scanning electron microscopy, and transmission electron microscopy. Surface enthalpy and enthalpy of water adsorption are reported for the first time. By adsorbing water, akaganeite decreases its effective surface enthalpy from 0.44 J/m2 to 0.34 J/m2. The enthalpy of formation of akaganeite can vary by 10-12 kJ/ mol as a function of the surface area. The standard enthalpy of formation of akaganeite with zero surface area was refined and is -554.7 ( 1.9 kJ/mol. Thus, the standard enthalpy of formation and surface enthalpy of akaganeite are between those of goethite and lepidocrocite. The more metastable the polymorph, the lower its surface energy.
L. Mazeina, S. Deore and A. Navrotsky, Chem. Mater.18 (2006) 1830-1838

B1639 – Surface energy and thermodynamic stability of gamma-alumina: Effect of dopants and water

Retaining large surface areas in alumina powders during high-temperature annealing is a major challenge in applications as catalyst supports and ceramic precursors. This is because the alumina surface area drastically decreases with transformation from the gamma modification (defect spinel structure) into the R modification (corundum structure). The objective of this work is to show the thermodynamic basis of using additives, such as Zr and Mg, to control the gamma-Al2O3 surface and bulk energetics and to manipulate the transformation temperature and surface area. These additives are observed to change the pattern of phase transformation and densification. Direct measurements of heats of solution in a lead borate melt of pure and doped alumina as a function of surface area enabled us to experimentally derive trends in the surface energies of hydroxylated surfaces. Accounting for heats of water adsorption measured on pure and doped alumina surfaces allowed us to delineate the thermodynamic effects of hydration on surface energies. Zr-doped gamma-alumina showed a higher energy of the hydroxylated surface than did pure ç-alumina but showed a lower energy of the anhydrous surface. Mg addition does not change surface energies significantly but decreases the energetic instability of the bulk gamma phase.
R.H.R. Castro, S.V. Ushakov, L. Gengembre, D. Gouve and A. Navrotsky, Chem. Mater. 18 (2006) 1867-1872

B1635 – Base adsorption calorimetry for characterising surface acidity: a comparison between pulse flow and conventional “static” techniques

A pulsed flow adsorption microcalorimeter (pulse-FMC) has been developed by modifying a Setaram 111. It is tested in comparison with a conventional pulsed static adsorption microcalorimeter (pulse-SMC) for characterising surface acidity of solid acid catalysts. Small pulses of 1% ammonia in helium are delivered to an activated catalyst sample and its surface acidity is differentially profiled in terms of the molar enthalpy of ammonia adsorption (?Hads°) using a combination of differential scanning calorimeter (DSC) and a downstream thermal conductivity detector (TCD). The pulsing action and its sequences are controlled by in-house developed software and the TCD output also is logged into a PC. Thus, the pulse-FMC is fully automated. Two sulfonated polystyrene resin-type catalysts, Amberlyst 15 and Amberlyst 35, a zeolite of the type H+-ZSM-5 (CT 410) and an acid activated clay (Fulcat 220) are characterised at appropriate temperatures using both the new technique and the conventional static base adsorption method. ?Hads° versus surface coverage profiles of all the four catalysts obtained from both pulse-FMC and the conventional method are found to be comparable. Results are interpreted in terms of the extent to which NH3 adsorption on the catalysts surface is under thermodynamic control in the two methods.
S.P. Felix, C. Savill-Jowitt and D.R. Brown, Thermochimica Acta 433 (2005) 59-65

B1603 – Study on chemisorption of H2, O2, CO and C2H4 on Pt-Ag/SiO2 catalysts by microcalorimetry and FTIR

Adsorption microcalorimetry has been employed to study the interaction of ethylene with the reduced and oxidized Pt-Ag/SiO2catalysts with different Ag contents to elucidate the modified effect of Ag towards the hydrocarbon processing on platinum catalysts. In addition, microcalorimetric adsorption of H2, O2, CO and FTIR of CO adsorption were conducted to investigate the influence of Ag on the surface structure of Pt catalyst. It is found from the microcalorimetric results of H2and O2adsorption that the addition of Ag to Pt/SiO2leads to the enrichment of Ag on the catalyst surface which decreases the size of Pt surface ensembles of Pt-Ag/SiO2catalysts. The microcalorimetry and FTIR of CO adsorption indicates that there still exist sites for linear and bridged CO adsorption on the surface of platinum catalysts simultaneously although Ag was incorporated into Pt/SiO2. The ethylene microcalorimetric results show that the decrease of ensemble size of Pt surface sites suppresses the formation of dissociative species (ethylidyne) upon the chemisorption of C2H4on Pt-Ag/SiO2. The differential heat vs. uptake plots for C2H4adsorption on the oxygen-preadsorbed Pt/SiO2and Pt-Ag/SiO2catalysts suggest that the incorporation of Ag to Pt/SiO2could decrease the ability for the oxidation of C2H4.
L. Li, X. Wang, J. Shen, L. Zhou and T. Zhang, Journal of Thermal Analysis and Calorimetry 82 (2005) 103-107

B1595 – Direct synthesis and characterization of hydrophobic aluminium-free Ti-beta zeolite

Incorporation of Ti into the framework of aluminium-free zeolite Beta has been achieved in F- medium and has produced hydrophobic selective oxidation catalysts. The Ti-Beta(F) materials have been characterized by X ray diffraction, infrared, Raman, ultraviolet, XANES, EXAFS, 29Si MAS NMR, and 1H29Si CP MAS NMR spectroscopies, adsorption microcalorimetry, and catalytic testing. At near neutral pH the incorporation of Ti into the framework appears to present an upper limit of ca. 2.3 Ti/uc, beyond which anatase is detected in the calcined materials. However, at higher pH (ca. 11) larger amounts of Ti can be incorporated without anatase formation. After calcination, Ti incorporation in the framework is characterized by an increase in the unit cell volume, the appearance of one Raman band and three infrared bands in the region near 960 cm-1 and the presence of a strong absorption band in the 205-220 nm ultraviolet spectrum. By 29Si MAS NMR, 1H29Si CP MAS NMR, and infrared spectroscopies it is concluded that upon contact with ambient humidity there is no hydrolysis of Si-O-Ti bonds in Ti-Beta zeolites prepared by the fluoride route, while it is probably a major feature of those synthesized in OH- medium. XANES and EXAFS spectroscopies of calcined dehydrated Ti-Beta zeolites unambiguously demonstrate the tetrahedral coordination of Ti with a Ti-O bond length of ca. 1.80 Å. Upon hydration, the changes in the XANES and EXAFS spectra are consistent with a change in the coordination of Ti to reach a state which depends on the composition and synthesis route and which ranges from a 5-fold coordination for Al-free Ti-Beta synthesized by the F- method to a highly distorted 6-fold coordination in Ti,Al-Beta synthesized in OH- medium. Adsorption microcalorimetry experiments show the strict hydrophobic nature of pure SiO2 zeolite Beta synthesized in F- medium while evidencing a slight increase in the hydrophilicity of the material upon incorporation of Ti to the framework. This is due to the relatively strong adsorption of precisely one H2O molecule per Ti site. On the contrary, the materials synthesized in OH- medium show an enhanced hydrophilicity. Finally, Ti-Beta(F) is an active and selective catalyst for oxidation of organic substrates with H2O2. A comparison of the activities and selectivities of Ti-Beta(F), Ti-Beta(OH) and TS-1 in the epoxidation of 1-hexene using acetonitrile and methanol as solvents demonstrates that the major differences between Ti-Beta and TS-1 catalysts are intrinsic to each zeolitic structure. Because of its high hydrophobicity, Ti-Beta(F) catalyst can advantageously replace Ti-Beta(OH) in the epoxidation of substrates, like unsaturated fatty acids or esters, which contain a polar moiety.
T. Blasco, M.A. Camblor, A. Corma, P. Esteve, J.M. Guil, A. Martinez, J.A. Perdigon-Melon, S.Valencia, J. of Physical Chemistry 102 (1998) 75-88

B1594 – Hydrogen adsorption on Rhodium particles supported on strontium titatanate as followed by 1H NMR and microcalorimetry

Hydrogen adsorption on supported rhodium particles has been studied by 'H NMR, volumetry, and microcalorimetry techniques. The amounts of hydrogen adsorbed on the metal and support have been evaluated. There is a good correlation between the shift of the NMR line assigned to hydrogen adsorbed on the metal and the mean integral heat involved in this adsorption. This permits an estimation of differential shifts corresponding to each dose. From analysis of differential NMR shift and differential adsorption heat, it is deduced that the hydrogen-metal interaction becomes weaker and less energetic with adsorption. This effect is discussed on the basis of the heterogeneity of the adsorption sites and a modification of the electronic properties at the metal surface.
J.M. Rojo, J.P. Belzunegui, J. Sanz and J.M. Guil, Journal of Physical Chemistry 98 (1994) 13631-13635

B1593 – Enthalpies of adsorption of hydrocarbons on discandium trioxide determined calorimetrically and from adsorption isotherms

Calorimetric measurements of the energy evolved on adsorption of ethene, propene, butane, and but-1-ene on a discandium trioxide sample at the temperature 298 K have been carried out as a function of the amount of substance adsorbed. The results have been used to discuss the application of thermodynamic equations relating the several energetic quantities involved. Particular attention has been paid to the compression work associated with the experimental adsorption processes. Calorimetric results have been compared with the isosteric enthalpies of adsorption previously determined from volumetric adsorption isotherms. They are in a good agreement. A proposal is made to use the differential molar energy of adsorption as a unique thermodynamic quantity to present results obtained by the different techniques.
J.M. Guil, A. Perez Masia, A. Ruiz Paniego, J.M. Trejo Menayo, J.Chem.Thermodynamics 25 (1994) 5-14

B1592 – Determining the topology of zeolites by adsorption microcalorimetry of organic molecules

Adsorption microcalorimetric studies of n-hexane, toluene, m-xylene and 1,3,5-trimethylbenzene on a bidimensional ten-member ring (MR) (ZSM-11), a unidirectional uniform 12-MR (SSZ-24), a constrained unidirectional (ZSM-12), a 12- and 8-MR (mordenite) and a 12- and 10-MR (CIT-1) zeolites have been carried out. It is shown that the adsorption of the four probe molecules followed by adsorption microcalorimetry allows the determination of the approximated micropore diameter. Comparison of the total uptake of each adsorbate can show the existence of micropore sets of different diameter. The variation of adsorption heat with uptake provides information on the surface chemistry allowing one to see if there is adsorption specificity or not. The packing molar densities inside the micropores give information on the particular micropore shape and the existence of cavities, lobes, etc. Finally, toluene or n-hexane post-adsorption experiments after preadsorption of a different adsorbate give information on the connectivities or crossing between sets of channels.
J.M. Guil, R. Guil-Lopez, J.A. Perdigon-Melon, A. Corma, Microporous and Mesoporous Materials 22 (1998) 269-279

B1591 – Determination of the pore topology of zeolite IM-5 by means of catalytic test reactions and hydrocarbon adsorption measurements

The pore topology of a recently synthesized zeolite IM-5 has been determined by means of catalytic test reactions, i.e., n-decane hydroisomerization-cracking, m-xylene isomerization-disproportionation, n-hexadecane isodewaxing, and adsorption-microcalorimetry of molecules with different sizes and shapes (n-hexane, toluene, m-xylene, and 1,3,5 trimethylbenzene). It has been found that the channel network consists of a system of unidirectional 10 MR with lobes or side pockets, or crossing 10 membered ring pores with a pore diameter somewhat smaller than those in ZSM-5. This structure offers interesting shape selectivity features for catalytic reactions.
A. Corma, A. Chica, J.M. Guil, F.J. Llopis, G. Mabilon, J.A. Perdigon-Melon, S.Valencia, Journal of Catalysis 189 (2000) 382-394

B1590 – Gas/surface titration microcalorimetry. Energetics of oxygen adsorption on supported iridium catalysts

Measurements of the heat of adsorption of hydrogen on Ir/Al2O3 catalysts of different metal particle size were made by employing adsorption microcalorimetry. The values of this quantity were different for each sample and the results also indicated the heterogeneity of the iridium surface. In contrast to this, the heat of adsorption of oxygen measured on the same samples in the same manner was practically the same for all of them. The heat of oxygen adsorption as presented in the differential calorimetric isotherms was constant up to half the monolayer coverage for all the samples. This result is unexpected and in contradiction to the presence of surface heterogeneity in the iridium crystallites, as revealed by hydrogen adsorption. To clarify these anomalies the energetics of oxygen adsorption was determined using a different method. Titration experiments with hydrogen of preadsorbed oxygen were carried out. The heat of adsorption of oxygen was calculated from these results by means of adopting a thermochemical cycle. The values of heat of adsorption obtained as a function of the amount adsorbed unveiled the heterogeneity of the iridium surface. The differences found between the samples can be correlated to both the different particle size and degree of sintering of the samples.
J.M. Guil, J.E. Herrero Garcia, A. Ruiz Paniego, J.M. Trejo Menayo, Topics in Catalysis 19 (2002) 313-321

B1589 – Microcalorimetric and infrared studies of ethanol and acetaldehyde adsorption to investigate the ethanol steam reforming on supported cobalt catalysts

Microcalorimetric and infrared studies of ethanol and acetaldehyde adsorption were carried out on fresh and deactivated ZnO-supported cobalt catalysts (Co/ZnO and Co/ZnO(d), respectively) as well as on ZnO support alone. The results were used to analyze the catalytic behavior of these materials for ethanol and acetaldehyde steam-reforming reactions. The Co/ZnO(d) sample contained extensive carbon deposition as shown by Raman spectroscopy and transmission electron microscopy. On fresh Co/ZnO, the adsorption energetics of ethanol and acetaldehyde (an intermediate in the ethanol reforming reaction) were similar. Under steam-reforming conditions at low conversion values of ethanol, acetaldehyde was selectively yielded. The presence of surface acetate species was shown from IR spectra following acetaldehyde adsorption. Besides that, the Co/ZnO catalyst was active and showed a high selectivity toward the reforming products, H2 and CO2, when the steam reforming of acetaldehyde was carried out at low conversion values. In contrast, on the deactivated sample, the strongest adsorption sites of ethanol have disappeared, and acetaldehyde was adsorbed with higher energy with respect to ethanol, resulting in the blockage of the active sites; a poorer catalytic performance in both ethanol and acetaldehyde steam-reforming reactions is observed. The presence of acetate species after adsorption of acetaldehyde on Co/ZnO(d) was not shown. The polymerization of acetaldehyde over Co/ZnO(d) was related to the decomposition of acetaldehyde under reforming conditions to give CO and CH4.
J.M. Guil, N. Homs, J. Llorca, P. Ramirez de la Piscina, J.Phys.Chem. B 109 (2005) 10813-10819

B1581 – Gas adsorption microcalorimetry: probing energetics of oxide surfaces

Novel instrumental design for adsorption microcalorimetry was developed at the UC Davis Thermochemistry Facility. It employs a modified surface area analyzer (Micromeritics ASAP 2020) for sample preparation, surface area determination and as an automated dosing system for the adsorbing gas [1]. A Calvet-type twin microcalorimeter (Setaram DSC 111) is used in isothermal mode for direct measurements of heats of adsorption. It enables measurement of heats of gas-solid interaction at temperature range from below room temperature to 800°C. Complementing oxide-melt solution calorimetry techniques with adsorption microcalorimetry data allows for experimental measurements of energies of both hydrated and anhydrous surfaces. Results of study of water adsorption on surfaces of zirconium, hafnium and aluminum oxides will be reported. These results have implications for nanoparticles encountered in geologic and environmental settings.
S.V. Ushakov and A. Navrotsky, UC Davis

B1561 – Calorimetric base adsorption and neutralisation studies of supported sulfonic acids

Base adsorption calorimetry (from the gas phase) and acid-base neutralisation titration calorimetry (in the liquid phase) have been used to characterise a series of solid sulfonic acids supported on porous silicas and polystyrene resins. The results illustrate the limitations of using calorimetric techniques for relative acidity measurements and the assumptions that must be made if molar enthalpies of adsorption or molar enthalpies of neutralisation are to be used to compare the strengths of solid acids. They also show how the relative acid strengths of nominally similar acids can be highly dependent on whether measurements are made in the presence or absence of a solvent, and, if the former, on the type of solvent.
S. Koujout, D.R. Brown, Thermochimica Acta 434 (2005) 158-164

B1560 – Calorimetric base adsorption and neutralisation studies of supported sulfonic acids

Base adsorption calorimetry (from the gas phase) and acid-base neutralisation titration calorimetry (in the liquid phase) have been used to characterise a series of solid sulfonic acids supported on porous silicas and polystyrene resins. The results illustrate the limitations of using calorimetric techniques for relative acidity measurements and the assumptions that must be made if molar enthalpies of adsorption or molar enthalpies of neutralisation are to be used to compare the strengths of solid acids. They also show how the relative acid strengths of nominally similar acids can be highly dependent on whether measurements are made in the presence or absence of a solvent, and, if the former, on the type of solvent.
S. Koujout, D.R. Brown, Thermochimica Acta 434 (2005) 158-164

B1559 – The coverage-dependent adsorption of carbon monoxide on hydrogen-reduced copper catalysts: the combined application of microcalorimetry, temperature-programmed desorption anf FTIR spectroscopy

The strong metal-support interactions occurring in Cu/ZnO catalysts are significantly influenced by the pretreatment. The objective of this contribution is to demonstrate that by carefully reducing binary Cu/ZnO and ternary Cu/ZnO/Al2O3 samples in hydrogen under the same conditions, the Cu metal surface is accessible in identical states to adsorption microcalorimetry, TPD experiments and transmission FTIR spectroscopy using carbon monoxide as probe molecule. All techniques show that a fully reduced and clean Cu surface is resulting from a thorough reduction in flowing high-purity hydrogen. The adsorption of CO on this Cu surface is fully reversible at room temperature, with heats of adsorption ranging between 70 kJ/mol at low coverages and 45 kJ/mol at high coverages.
R. Naumann d'Alnoncourt, M. Bergmann, J. Strunk, E. Löffler, O. Hinrichsen, M. Muhler, Thermochimica Acta 434 (2005) 132-139

B1558 – Microcalorimetric studies and methane reforming by CO2 on Ni-based zeolite catalysts

A series of catalysts containing nickel, based on HZSM-5 and USY zeolites, have been prepared by ionic exchange; a Ni/y-Al2O3 catalyst has been prepared by impregnation, for comparison. Ammonia and CO adsorption microcalorimetry and temperature programmed reduction experiments have shown that NiZSM-5 is the most acidic and the most reducible catalyst. The study of the reaction of methane reforming by carbon dioxide in presence of these catalysts has shown that the catalytic performance depends simultaneously on the acidity, reducibility, and structure of the zeolite. Globally, it appears that the catalytic properties of NiUSY are superior to those of NiZSM-5 and Ni/y-Al2O3.
D. Halliche, O. Cherifi et A. Auroux, Thermochimica Acta 434 (2005) 125-131

B1557 – Microcalorimetric studies of the iridium catalyst for hydrazine decomposition reaction

Microcalorimetric studies of H2, NH3 and O2 adsorption, as well as the NH3 decomposition activities evaluation were used to characterize the iridium catalysts for hydrazine decomposition with different supports (Al2O3, SiO2) and iridium contents (1.8, 10.8 and 22.1%). The higher H2 chemisorption amounts on Ir/Al2O3 catalysts than those on the corresponding Ir/SiO2 counterparts revealed that the strong interaction of iridium and Al2O3 led to higher dispersion of iridium on Ir/Al2O3 catalysts than on Ir/SiO2 catalysts. The larger increase in strong H2 adsorption sites on highly loaded Ir/Al2O3 than the corresponding Ir/SiO2 ones could be attributed to the interaction not only between iridium atoms but also between iridium and Al2O3. The microcalorimetric results for NH3 adsorption showed that no apparent chemisorption of NH3 existed on Ir/SiO2 catalysts while NH3 chemisorption amounts increased on Ir/Al2O3 catalysts with iridium loadings, which arose from the interaction of the catalysts support of Al2O3 with chloride anion. Both highly dispersed iridium active sites and chloride anion on Ir/Al2O3 catalysts could be beneficial to the intermediate NH3 decomposition in N2H4 decomposition. The similar O2 plots of differential heat versus normalized coverage on Ir/Al2O3 and Ir/SiO2 catalysts could not be due to the metal-support interaction, but to the formation of strong IrO bond.
L. Li, X. Wang, X. Zhao, M. Zheng, R. Cheng, L. Zhou, T. Zhang, Thermochimica Acta 434 (2005) 119-124

B1556 – Study of CO chemisorption on graphite-supported Ru-Cu and Ni-Cu bimetallic catalysts

The adsorption of CO on graphite-supported monometallic catalysts (Ni and Ru) and bimetallic catalysts (Ru-Cu and Ni-Cu) reduced at different temperatures was studied by microcalorimetry. The calorimetric profiles obtained over these two bimetallic systems provides information about the different types of interaction (bridged, linear or subcarbonyl species) that could exist in the bimetallic system when Cu was introduced in the Ru and Ni monometallic catalysts.
E. Asedegbega-Nieto, A. Guerrero-Ruiz, I. Rodriguez-Ramos, Thermochimica Acta 434 (2005) 113-118

B1555 – Adsorption calorimetry in supported catalyst characterization : adsorption structure sensitivity on Pt/gamma-Al2O3

In this study, the structure sensitivity of hydrogen, oxygen and carbon monoxide adsorption was investigated by changing the metal particle size of Pt/Al2O3 catalysts. The 2% Pt/Al2O3 catalysts were prepared by incipient wetness method; the particle size of the catalysts was modified by calcining at different temperatures. The differential heats of adsorption of hydrogen, carbon monoxide and oxygen were measured using a SETARAM C80 Tian-Calvet calorimeter. Hydrogen chemisorption sites with low and intermediate heats were lost when the particle size increased consistent with the previous reports in the literature. No structure dependency was observed for hydrogen, carbon monoxide or oxygen initial heats of adsorption. The adsorbate:total metal stoichiometries at saturation systematically decreased with increasing particle size. While the hydrogen site energy distribution changed with increasing particle size, oxygen and carbon monoxide adsorption site energy distributions did not change appreciably with the metal particle size.
D. Uner, M. Uner, Thermochimica Acta 434 (2005) 107-112

B1554 – Surface sites on carbon-supported Ru, Co and Ni nanoparticles as determined by microcalorimetry of CO adsorption

The adsorption of CO on carbon-supported metal (Ru, Co and Ni) catalysts was studied by microcalorimetry. A correlation of the results thus obtained with those reported for monocrystals or with other studies available in the scientific literature for supported metal catalysts, including infrared spectroscopy data, enables the determination of the type of exposed crystalline planes and/or of the different types of CO adsorbed species. The results obtained suggest that the energetic distribution of the surface sites depends on the carbon support material and on the applied reduction treatment. In this way, the use of a high surface area graphite (clean of surface oxygen groups) leads to an electron density enrichment on the small metal particles (Ru) and, in general, to a higher heterogeneity of the active surface sites. The elimination of surface oxygen functional groups (with the reduction treatment at the higher temperature) of the carbon molecular sieve support leads to changes in the surface structure of the metal particles and, consequently, to higher CO adsorption heats, particularly for Ru and Co.
M. Cerro-Alarcon, A. Maroto-Valiente, I. Rodrigez-Ramos, A. Guerrero-Ruiz, Thermochimica Acta 434 (2005) 100-106

B1553 – Effect of the basicity created by La2O3 addition on the catalytic properties of Co(O)/SiO2 in CH4 + CO2 reaction

A series of Co(O)/SiO2 catalysts modified by various amounts of La2O3 (5, 10 or 50 wt.%) were synthesized and studied in the reaction of reforming of methane by carbon dioxide to syngas at the temperature of 873 K. The catalysts were prepared by successive incipient wetness impregnation: La2O3-SiO2 supports were first prepared by impregnating silica with La(NO3)3 solutions. After drying and calcining under airflow, samples were then submitted to a second impregnation with Co(NO3)2. The purpose of this work is to study the acid-base property of these catalysts by CO2 adsorption calorimetry at 353 K and to look at their impact on the catalytic property. The amounts of chemisorbed CO2 and the site strength distribution of the basic sites, i.e., the basicity, were shown to be strongly dependent on La2O3 content. The following order of basicity was observed: Co(O)/5 wt.%La2O3-SiO2 < Co(O)/10 wt.%La2O3-SiO2 Co(O)/50 wt.%La2O3-SiO2. The addition of La2O3 to the Co(O)/SiO2 reference sample revealed a very positive effect on the catalytic stability of catalysts. La2O3 prevented cobalt phase sintering by avoiding particle coalescence.
R. Bouarab, O. Cherifi, A. Auroux, Thermochimica Acta 434 (2005) 69-73

B1552 – Characterization of monofunctional ZrO2-MoO3 catalysts for methylcyclopentane conversion

A series of ZrO2-MoO3 catalysts with different molybdenum loadings (0-18.7 at.% Mo) prepared by co-precipitation were characterized and evaluated for their performance for methylcyclopentane (mcp) conversion. The dependence of Mo content on the crystallinity, surface area, and acidic properties of ZrO2-MoO3 is studied and evaluated as a function of molybdenum loading. The monoclinic phase is observed at low Mo loadings, with the tetragonal polymorph of ZrO2 effectively stabilized at higher Mo loadings. The surface area of ZrO2-MoO3 increases with molybdenum content to a maximum value of 124 m2 g-1 at a loading of 15.8 at.% Mo, followed by a decrease at higher Mo loadings. Isothermal CO2 adsorption and ammonia TPD results indicate the strength of basic sites and specific NH3 desorption decreases with increasing molybdenum content, while TPR indicates ZrO2-MoO3 catalysts are more easily reduced with increasing molybdenum loading. The most active catalyst for mcp conversion (36% conversion) corresponds to a molybdenum loading of 3.2 at.% Mo, which has the highest acidity per surface area of the ZrO2-MoO3 catalysts studied.
C. Kenney, Y. Maham, A. E. Nelson, Thermochimica Acta 434 (2005) 55-61

B1551 – Surface acidity of catalytic solids studied by base desorption : experimental and modelling approaches

A thermogravimetric analyzer (TGA) was used to collect thermodesorption curves of 2-phenylethylamine (PEA) from acidic surfaces with the aim of determining the amount and distribution of the acid sites of the samples. Oxides widely used as active phase supports as well as catalytic phases were selected for this study: alumina, silica, silica-alumina, silica-zirconia, and silica-titania. The thermodesorption curves were collected at different heating rates (5 < beta (°C/min) < 30) in inert atmosphere. The activation energies of PEA desorption from the acid sites were calculated from the dependence upon the heating rate beta of the displacements of the observed desorption peaks (Tmax) as determined from the derivative of the TGA profiles (DTGA). For a more accurate kinetic study of the desorption phenomenon, a kinetic model based on parallel reactions of desorption, each one running with its own kinetic parameter in a temperature-dependent manner in accordance with Arrhenius's law, was applied to the experimental desorption data at the different heating rates. The quantitative acid site energy distribution was optimized for each sample, and kinetic parameters for each type of acid site were determined. The conclusions drawn from PEA thermodesorption were compared with the results obtained from the differential heat curves of ammonia adsorption measured at 80°C in a volumetric-calorimetric line.
A. Gervasini, P. Carniti, A. Auroux, Thermochimica Acta 434 (2005) 42-49

B1549 – Calorimetric investigation on zeolites, AlPO4’s and CaCl2 impregnated attapulgite for thermochemical storage of heat

The sorption properties of water in potential thermochemical storage materials such as low silica X zeolites, microporous aluminophosphates, SAPO-34 and CaCl2 accommodated in the pores of attapulgite were investigated by thermogravimetry, differential scanning calorimetry, sorption isotherms and microcalorimetry. Because of decreasing differential molar heats of sorption from LiLSX (100-70 kJ/mol) to SAPO-34 (90-65 kJ/mol) and to supported CaCl2 (70-50 kJ/mol) the isotherms are shifted towards higher equilibrium pressure by about three orders of magnitude. The energy densities at 313 K and up to 20 mbar vapor pressure decrease in the same order from 1184 to 997 and 871 kJ/kg adsorbens. The average temperatures for the desorption of the water decreases as well from >450 to <400 K which classifies the silicoaluminophosphate between the common zeolites and the salt hydrates with regard to the properties as thermochemical storage material.
J. Jänchen, D. Ackermann, E. Weiler, H. Stach, W. Brösicke, Thermochimica Acta 434 (2005) 37-41

B1548 – Flow calorimetric and thermal gravimetric study of adsorption of thiophenic sulfur compounds on NaY zeolite

A study of adsorption of thiophenic sulfur compounds (thiophene, benzothiophene, dibenzothiophene and 4,6-dimethyl benzothiophene) in normal alkane solvents (octane, dodecane and hexadecane) on NaY zeolite has been performed by using flow calorimetry technique and thermogravimetric analysis. The measured heat of adsorption of sulfur compounds includes the heat from the displacement of the adsorbed solvent molecules by sulfur compounds and it is therefore much lower than that obtained by gas phase adsorption of sulfur compounds in the zeolite. The apparent heat of adsorption of sulfur compounds per gram of sorbent decreases when the solvent changes from octane, dodecane to hexadecane, but the heat of adsorption per mole of sulfur compound calculated based on the sorption data does not vary significantly with the solvent used. The measured heat of adsorption per gram of sorbent is also influenced by the molecular size of the sulfur compound and decreases in the order: thiophene > benzothiophene > dibenzothiophene due to the higher sorbent capacity for the smaller sulfur compound. Thermogravimetric analysis of the adsorbed sulfur compounds under combustion condition used for the sulfur elimination from the sorbent indicates that the combustion of the refractory sulfur compounds occurs at higher temperatures. Analysis of the effluent from the calorimeter could be used to estimate the breakthrough characteristics of the sorbent. This indicates that the flow calorimetry is a promising technique for establishing the relationship between sorption capacity and heat of adsorption of sulfur compounds. The information obtained from the flow calorimetry and thermogravimetry could be used for the development of selective sorbents for the production of ultra-clean fuels.
M. Jiang, F.T.T. Ng, A. Rahman, V. Patel, Thermochimica Acta 434 (2005) 27-36

B1547 – Surface acidity and the dehydration of methanol to dimethyl ether

Microcalorimetry and infrared spectroscopy for ammonia adsorption have been used to study the nature, strength and number of surface acid sites of H-ZSM-5, steam de-aluminated H-Y zeolite (SDY), y-Al2O3 and Ti(SO4)2/y-Al2O3 catalysts for the dehydration of methanol to dimethyl ether (DME). The conversion of isopropanol was also performed as a probe reaction to characterize the acid strength. The H-ZSM-5 and SDY possessed strong Bronsted acidity and exhibited high activity for the conversion of methanol to DME at relatively low temperatures, but they did not seem to be suitable as the dehydration component of the hybrid catalyst for the direct synthesis of DME from syngas since the two zeolite catalysts produced hydrocarbons and coke from methanol at temperatures higher than 513 K. The coke was serious over the two zeolite catalysts at 553 K. The dehydration of methanol to DME on y-Al2O3 was found to be low at the temperatures below 573 K though the DME selectivity is high. The modification of the y-Al2O3 by Ti(SO4)2 greatly enhanced the surface Bronsted acidity and also the reaction activity for the dehydration of methanol to DME. In addition, no detectable hydrocarbon by-products and coke were formed on the Ti(SO4)2/y-Al2O3 catalyst in the temperature range of 513-593 K. Thus, the Bronsted acid sites with suitable strength may be responsible for the effective conversion of methanol to DME with high stability.
Y. Fu, T. Hong, J. Chen, A. Auroux, J. Shen, Thermochimica Acta 434 (2005) 22-26

B1526 – Free radicals in catalytic oxidation of light alkanes: kinetic and thermochemical aspects

The kinetic and thermochemical analyses of the catalytic oxidation of C1---C4 alkanes indicate that the overall reaction network includes both homogeneous and heterogeneous elementary reactions of free radicals. Two thermochemical parameters of oxide catalysts, the affinity of the surface active site E[O---H] to a hydrogen atom and oxygen binding energy E[O], are the main factors determining the kinetic features of the overall process. The possible contribution of free radical reactions to some metal-catalyzed processes (steam reforming, partial and total oxidation of methane) is analyzed. Trends in the studies of catalytic chemistry of free radicals and in the development of innovative catalytic processes of light alkane transformation into valuable products are discussed.
M.Y. Sinev, Journal of Catalysis 216 (2003) 468-476

B1521 – Etude thermodynamique du polymère super absorbant X10 vis-à-vis de l’eau vapeur

M. Bakass, J. P. Bellat, A. Mokhlisse, G. Bertrand, 30ieme JEEP (2005) 21-23

B1514 – Calorimetric determination of the acidic character of amorphous and crystalline aluminosilicates

Aluminosilicates can present different structures such as crystalline true zeolite molecular sieves or amorphous silica-aluminas. With a large surface area available, both can be involved as catalysts, adsorbents or catalyst supports, and the determination of their surface acidic properties is an important parameter in the study of such materials. The number, strength and strength distribution of the acidic sites were determined using microcalorimetry linked to a volumetric line. Ammonia was used as a basic probe molecule. The adsorption temperatures ranged from 353 K up to 473 K. The samples consisted of two amorphous silica-aluminas (Si/Al ? 6.5) and three microporous zeolites H-beta, H-ZSM-5 and H-MCM-22 with similar Si/Al ratios (Si/Al ? 13). The differential heats of ammonia adsorption versus coverage and the corresponding isotherms are given. The H-ZSM-5, H-MCM-22, H-beta samples display a plateau of constant adsorption heats near 150 kJ mol-1, while the silica-alumina samples present continuously decreasing heats from 150 kJ mol-1 at zero coverage to 40 kJ mol-1 at high coverage, due to their surface heterogeneity. For amorphous silica-aluminas, the number of acid sites is dependent of the aluminum distribution at the surface. The differences observed in the adsorption behavior of ammonia over the three zeolites arise from differences in their morphology, i.e. the total free volumes, pore geometries and electric field gradients at the adsorption sites. The adsorption isosteres have also been calculated from the adsorption isotherms, and the isosteric heats of adsorption have been compared with the heats measured by calorimetry.
B. Dragoi, A. Gervasini, E. Dumitriu, A. Auroux, Thermochimica Acta 420 (2004) 127-134

B1512 – Calorimetric study of room temperature adsorption of N2O and CO on Cu(II)-exchanged ZSM5 zeolites

Copper ion-exchanged ZSM5 zeolites have been prepared with different cooper loadings from under- to over-exchanged levels. The adsorptions of N2O and CO at 303 K have been studied using calorimetric method and infrared spectroscopy. The samples were additionally characterised by ammonia adsorption at 423 K. The active sites for both N2O and CO are Cu(I) ions, which were formed as a result of pre-treatment in vacuum at 673 K. Room temperature adsorption of nitrous oxide at low equilibrium pressures (up to 66.7 Pa) resulted in small amounts of chemisorbed N2O (<0.2 molecule per one Cu ion). Differential heats of N2O adsorption between 80 and 30 kJ/mol were obtained. Differential heats of CO adsorption between 140 and 40 kJ/mol were obtained. The obtained amounts of chemisorbed species in the investigated systems and the values of differential heats of both nitrous oxide and carbon monoxide demonstrate the dependence on the copper content.
V. Rakic, V. Dondur, S. Gajinov, A. Auroux, Thermochimica Acta 420 (2004) 51-57

B1491 – Characterisation of Lewis and Bronsted acidic sites in H-MFI and H-BEA zeolites: a thermodynamic and ab initio study

Adsorption enthalpies of N2, CO, CH3CN and NH3 on H-BEA and H-MFI zeolites have been measured calorimetrically at 303K in order to assess the energetic features of the various interactions occurring within the zeolite nanocavities, namely: (i) specific adsorption on Lewis and Bronsted acidic sites; (ii) H-bonding interactions with hydroxyl nests; (iii) dispersive forces interactions with the walls of the cavities (confinement effects). Confinement effects have been investigated on an all-silica MFI zeolite (silicalite). The interaction of the molecular probes with model clusters mimicking Lewis and Bronsted sites has been simulated at ab initio level. The combined use of the two different approaches allowed to discriminate among the different interactions contributing to the measured heat of adsorption (-?adsH). Whereas CO and N2 single out contributions from Lewis and Bronsted acidic sites, CH3CN and NH3 are not preferentially adsorbed on Lewis sites, suggesting that the adsorption on Bronsted sites is competitive with Lewis sites. The zero-coverage heats of adsorption for the different probes on the various systems correlate well with the proton affinity (PA) of the molecular probes.
C. Busco, A. Barbaglia, M. Broyer, V. Bolis, G. M. Foddanu, P. Ugliengo, Thermochimica Acta 418 (2004) 3-9

B1436 – Acidities and catalytic activities of persulfonated poly(styrene-co-divinylbenzene) ion-exchange resins

A series of macroporous sulfonated poly(styrene-co-divinylbenzene) ion-exchange resins with varying levels of sulfonation have been prepared. The acidities of these resins have been measured calorimetrically by ammonia sorption. Catalytic activities have been measured in two liquid-phase reactions: the dehydration of 1-hexanol under flow conditions and the hydration of propene as a batch process. The molar enthalpies of ammonia sorption show that the strength of the acid sites increases as the level of sulfonation is increased; catalytic activities follow the same trend. The most active resins are those that have been sulfonated at levels above one sulfonic acid group per aromatic ring ("persulfonated"). These persulfonated resins also show higher thermal stabilities than conventional resins (sulfonated at just below one acid group per aromatic ring).
M. Hart, G. Fuller, D.R. Brown, C. Park, M.A. Keane, J.A. Dale, C.M. Fougret, R.W. Cockman, Catalysis Letters 72 (2001) 135-139

B1432 – Acid-base properties of a ceria-lanthana catalytic system

A ceria-lanthana system was prepared by the sol-gel technique in order to obtain active catalysts for the 4-methylpentan-2-ol conversion. As the products distribution strongly depends on the acid-base features of the catalyst, acidity and basicity of the CeO2-La2O3 samples were determined by adsorption microcalorimetry, using ammonia and carbon dioxide as probe molecules. Both concentration and strength of the sites were assessed and their nature was investigated by analysing the microcalorimetric data in the light of the structural and textural characterisation previously carried out. Present samples are compared to a formerly investigated ceria-lanthana system prepared by a different procedure.
M.G. Cutrufello, I. Ferino, E. Rombi, V. Solinas, G. Colon, J.A. Navio, Journal of Thermal Analysis and Calorimetry 72 (2003) 223-229

B1431 – Surface acidity of supported vanadia catalysts

The surface acidity of SiO2, -Al2O3 and TiO2 supported vanadia catalysts has been studied by the microcalorimetry and infrared spectroscopy using ammonia as the probe molecule. The acidity in terms of nature, number and strength was correlated with surface structures of vanadia species in the catalysts, characterized by X-ray diffraction and UV-Vis spectroscopy. It was found that the dispersion and surface structure of vanadia species depend on the nature of supports and loading and affect strongly the surface acidity. On SiO2, vanadium species is usually in the form of polycrystalline V2O5 even for the catalyst with low loading (3%) and these V2O5 crystallites exhibit similar amount of Brönsted and Lewis acid sites. The 25%V2O5/SiO2 catalyst possesses substantial amount of V2O5 crystallites on the surface with the initial heat of 105 kJ mol-1 and coverage of about 600 µmol g-1 for ammonia adsorption. Vanadia can be well dispersed on -Al2O3and TiO2 to form isolated tetrahedral species and polymeric two-dimensional network. Addition of vanadia on -Al2O3 results in the change of acidity from that associated with -Al2O3 (mainly Lewis sites) to that associated with vanadia (mainly Brönsted sites) and leads to the decreased acid strength. The 3%V2O5/TiO2 catalyst may have the vanadia structure of incomplete polymeric two-dimensional network that possesses the Ti-O-V-OH groups at edges showing strong Brönsted acidity with the initial heat of about 140 kJ mol-1 for ammonia adsorption. On the other hand, the 10%V2O5/TiO2 catalyst may have well defined polymeric two-dimensional vanadia network, possessing V-O-V-OH groups that exhibit rather weak Brönsted acidity with the heat of 90 kJ mol-1 for NH3 adsorption. V2O5 crystallites are formed on the 25%V2O5/TiO2 catalyst, which exhibit the acid properties similar to those for 25%V2O5 on SiO2 and -Al2O3.
H. Zou, M. Li, J. Shen, A. Auroux, Journal of Thermal Analysis and Calorimetry 72 (2003) 209-221

B1430 – Acid-base properties of MgCuAl mixed oxides

MgCuAl layered double hydroxides (LDHs) with a hydrotalcite like structure containing different proportions of Mg2+ and Cu2+ cations have been prepared. Thermogravimetry and X-ray diffraction data indicated that the transformation of LDH into mixed oxides is effective after calcination at 723 K, irrespective of the composition. The acid-base properties of these mixed oxides have been investigated using adsorption microcalorimetry and X-ray photoelectron spectroscopy with NH3 (for acidity) and SO2 (for basicity) as probe molecules. Their catalytic behaviour for the conversion of cyclohexanol has been tested. The acid-base properties and the selectivity of catalysts has been related to their composition.
S. Casenave, H. Martinez, C. Guimon, A. Auroux, V. Hulea, E. Dumitriu, Journal of Thermal Analysis and Calorimetry 72 (2003) 191-198

B1422 – Calorimetric study of methane interaction with supported Pd catalysts

As supported palladium oxide catalysts present the best performances in methane combustion in lean conditions, microcalorimetric studies of the interaction between methane and palladium oxide or metallic palladium supported on Al2O3, ZrO2 and BN have been performed at 673 K. At this temperature methane reduced the palladium oxide, and the heat of reduction of palladium oxide was shown to depend on the dispersion and on the support. The lowest heats of reduction corresponded to the highest rates of methane combustion. Moreover methane reforming occurred on metallic palladium, producing hydrogen, and again methane decomposition was shown to depend on the support.
J.A. Perdigon-Melon, A. Auroux, B. Bonnetot, Journal of Thermal Analysis and Calorimetry 72, (2003) 443-451

B1414 – Etude de l’acidité de zéolithes Y modifiées par différents cations : application à la réaction de reformage sec du méthane

A series of modified zeolite catalysts (HYM) was prepared by ion-exchange of a commercial faujasite Y by various cations (M=Ni, Cr, Fe, Li, Ce). The exchange level was calculated from the chemical analysis results. The acidity of the samples was determined by ammonia adsorption calorimetry which allowed the simultaneous determination of the number and strength of the acid sites. The order of acidity obtained was the following: HYCr>HY>HYNi>HYLi>HYFe>HYCe. These catalysts were tested in the dry reforming reaction of methane by carbon dioxide in the 400-700°C domain, under atmospheric pressure. The best catalytic performances were observed with the HYNi sample which displayed methane and dioxide conversions of 74,1 and 78,5% respectively
D. Halliche, O. Cherifi et A. Auroux, Journal of Thermal Analysis and Calorimetry 68 (2002) 997-1002

B1397 – Thermal characterization of titania-modified alumina-supported palladium and catalytic properties for methane combustion

Thermal characterization of Pd/TiO2-Al2O3 catalysts under oxygen or hydrogen atmosphere was investigated by means of thermogravimetry (TG), differential scanning calorimetry (DSC), temperature programmed reduction (TPR) and temperature programmed desorption (TPD). Further, the effects of titania on the catalytic property of Pd/Al2O3 towards methane combustion were also examined. A TG-DSC studies revealed that the heat evolved during oxygen adsorption at 25°Cdepended on the crystallite diameter. TPR and TPD studies of oxidized samples also demonstrated that the coating of Pd/Al2O3 catalysts with titania can weaken the strength of the Pd---O bonds. Apparently the effect of coating Pd/Al2O3 catalyst with TiO2 is the improvement of the methane combustion at lower temperatures. This is probably due to the decrease of the strength of the Pd---O bonds.
C.B. Wang, H-G. Lee, T-F. Yeh, Thermochimica Acta 401 (2003) 209-216

B1384 – Sulfonated poly(styrene-co-divinylbenzene) ion-exchange resins: acidities and catalytic activities in aqueous reactions

A series of sulfonated poly(styrene-co-divinylbenzene) ion-exchange resins with varying levels of sulfonation has been prepared. The acidities of these resins in the hydrated form have been characterised microcalorimetrically by titration with aqueous NaOH solution. The resultant molar enthalpies of neutralisation have been compared with acid strengths of the same resins measured in the absence of water by ammonia adsorption microcalorimetry, and catalytic activities in two test reactions, the dehydration of 1-hexanol and the hydration of propene. The molar enthalpies of neutralisation of hydrated resins with aqueous NaOH have been shown to increase with increasing sulfonation level. This has been explained in terms of an increasing concentration of sulfonic acid in the internal gel solution, generating stronger acid sites and higher specific catalytic activities. A similar trend of increasing acid strengths has been observed in anhydrous resins, but this has been explained in terms of structural features such as di-substitution of sulfonic acid groups on styrene units, giving rise to intrinsically stronger acid sites.
M. Hart, G. Fuller, D.R. Brown, J.A. Dale and S. Plant, Journal of Molecular Catalysis A: Chemical 182-183 (2002) 439-445

B1383 – Microcalorimetric and catalytic studies on sulfated zirconia catalysts of different preparations

Sulfated and metal ion-promoted sulfated zirconia were synthesized by freeze-drying as well as by conventional and aerogel synthesis. The acidity of the samples was studied by means of microcalorimetry; the catalytic performance of the samples was evaluated in the reaction between benzoic anhydride and anisole at 50±C and RT. Supercritical drying and freeze-drying gave access to sulfated zirconia with large pore diameters and pore volumes. As a result, high conversions in the Friedel-Crafts acylation were observed; a further increase in activity was achieved by metal ion promotion. The results of the benzoylation reaction were related to data from microcalorimetric experiments. The adsorption was performed not only with ammonia and pyridine in the gas phase, but also with a mixture of pyridine in anisole, much more consistent with the catalysis conditions. Only from the latter experiments, the higher catalytic performance of cryogel and aerogel samples was confirmed. Therefore, using such liquid mixtures might be a suitable method to distinguish between good acylation catalysts and less active samples.
V. Quaschning, A. Auroux, J. Deutsch, H. Lieske, E. Kemnitz, Journal of Catalysis 203 (2001) 426-433

B1379 – From strong solid acids to strong solid bases: characterization of the acid/base centers of catalyst surfaces by adsorption microcalorimetry

A. Auroux, Natas (2001) 53-58

B1377 – Adsorption microcalorimetry : refining the continuous flow technique

R. Murdey, P. Llewellyn, Y. Grillet, Fondamental of Adsorption 6 (1998) 117-122

B1373 – Microcalorimetric methods for studying vapour adsorption and wetting of powders

The interaction of a powder with vapours or their wettability by liquids are involved in many industrial processes and then needs to be studied by simple and reproducible methods. Two microcalorimetric methods, one for the simultaneous measurement of adsorption isotherm and enthalpy and the other for the determination of wetting or immersion energy, are described. A few examples are given for the adsorption and wetting of powders by water and organic vapours.
R. Denoyel, I. Beurroies, D. Vincent, Journal of Thermal Analysis and Calorimetry 70 (2002) 483-492

B1370 – Correlation between surfaces areas and micropore volumes of activated carbons obtained from physical adsorption and immersion calorimetry

The heats of immersion of a series of activated carbons with increasing porosity into a number of liquids with different molecular sizes (benzene, 2,2-dimethylbutane and isooctane) have been measured at 303 K. The experimental values have been used to calculate the corresponding surface areas (using a nonporous carbon (V3G) as reference) and micropore volumes. These parameters have been compared with those obtained from physical adsorption of Nz at 77 K and of the same hydrocarbons at 298 K. A good correlation has been found between the values obtained from both techniques provided no lack of accessibility of the liquid or vapor to the whole microporous structure of the carbon is present.
M.T. Gonzalez, A. Sepulveda-Escribano, M. Molina-Sabio, F. Rodriguez-Reinoso, Langmuir 11 (1996) 2151-2155

B1369 – Surface properties of activated carbons in relation to their ability to adsorb nonylphenol aqueous contaminant

Pure organic nitro compounds, i.e., aromatic or aliphatic nitro compounds, decompose at high temperatures, exhibiting large decomposition exotherms. In most cases, the decomposition is violent or explosive. In practical process situations, nitro compounds are mixed with other chemicals or contaminated by impurities which lower their thermal stability. Contaminated nitro compounds or solutions of nitro compounds may decompose at much lower temperatures than the pure products. Their decomposition is less rapid but remains highly exothermic. Therefore, for practical reasons, the most relevant information in the field of process safety is to describe how reactants, solvents, and impurities may affect the organic nitro compounds' thermal stability and in which process situations this may be a hazard.
D.M. Nevskaia, A. Sepulveda-Escribano, A. Guerrero-Ruiz, Phys. Chem. Chem. Phys. 3 (2001) 463-468

B1368 – Characterization of microporous solids by immersion calorimetry

This paper reviews the fundamentals and main applications of immersion calorimetry in the study of microporous adsorbents such as activated carbons, including carbon molecular sieves, and microporous zeolites. In the former case, it will be shown that immersion calorimetry into liquids of different molecular sizes easily allows for the assessment of the micropore size distribution. Furthermore, the use of liquids with different polarity permits the study of the evolution of the surface chemistry of these materials after different treatments. On the other hand, the study of zeolites with this technique is not as straightforward as in the case of carbonaceous materials, given the higher complexity of these systems. It will be shown that this technique can be used to analyze the evolution of the surface properties of zeolites A and X after thermal treatments at different temperatures and after ion-exchange.
J. Silvestre-Albero, C. Gomez de Salazar, A. Sepulveda-Escribano, F. Rodriguez-Reinoso, Colloids and Surfaces A Physicochemical & Engineering Aspects 187-188 (2001) 151-165

B1367 – Use of immersion calorimetry to evaluate the separation ability of carbon molecular sieves

The effect of different preparation parameters (pyrolysis temperature, process time, benzene concentration and residence time) on the properties of carbon molecular sieves obtained by pyrolytic carbon deposition from benzene on a microporous activated carbon, has been studied. For a fixed process time of 2 h, the increase of the pyrolysis temperature from 525 to 700
C.G. de Salazar, A. Sepulveda-Escribano, F. Rodriguez-Reinoso, Studies in Surface Science and Catalysis 128 (2000) 303-312

B1352 – Calorimetric study of interaction between oxygen and B-AL2O3, B-AL2O3+Au and B-AL2O3+Pt

In an attempt to improve the understanding of the electrochemical effects observed on an original potentiometric gas sensor, interactions of oxygen with the device were investigated. These calorimetric measurements have evidenced the existence of a weakly bounded endothermal oxygen species. Moreover these species may be regarded to be responsible for the electrical response developed by the sensor. Such results, which are in agreement with a previously proposed model, validate the underlying hypothesis and shed light on the role of oxygen in the sensor's responses.
N. Guillet, C. Pijolat, R. Lalauze, Journal of Thermal Analysis and Calorimetry 68 (2002) 15-23

B1344 – Calorimetric investigations on kinetics of the dehydrogenation process in the system lanthanum-magnesium-hydrogen

A kinetic study of the dehydrogenation of several magnesium-based alloys/compounds with lanthanum is presented and the results are referred to the kinetics of the dehydrogenation process of pure magnesium hydride. Measurements were performed in a differential scanning calorimeter (DSC) by applying various pressure steps to the samples at isothermal conditions. Different thermokinetic models were fitted to the experimental obtained DSC curves as well as the power curves, calculated from the DSC curves, to evaluate the kinetic parameters. The derived dehydrogenation rate is discussed in terms of their dependence on hydrogen pressure and temperature. Under certain conditions, it is possible to visualise individual rate-determining steps. Considering these results first mechanistic considerations on the dehydrogenation reaction of the magnesium-based alloys/compounds can be drawn.
B. Bernhardt, K. Bohmhammel, Thermochimica Acta 382 ( 2002) 249-254

B1326 – Calorimetric characterization of surface reactivity of supported Ga2O3 catalysts

The surface properties of supported gallium oxide catalysts prepared by impregnation of various supports (-Al2O3, SiO2, TiO2, ZrO2) were investigated by adsorption microcalorimetry, using ammonia and water as probe molecules. In the case of acidic supports (-Al2O3, ZrO2, TiO2), the acidic character of supported gallium catalysts always decreased in comparison with gallium-free supports; on very weakly acidic SiO2, new acidic centers were created when depositing Ga2O3. The addition of gallium oxide decreased the hydrophilic properties of alumina, titania and zirconia, but increased the amount of water adsorbed on silica. The catalytic performances inthe selective catalytic reduction of NO by C2H4 in excess oxygen were in the order Ga/Al2O3>Ga/TiO2>Ga/ZrO2>>Ga/SiO2. This order is more related to the quality of the dispersion of Ga2O3 on the support than to the global acidity of the solids.
A.L. Petre, A. Auroux, A. Gervasini, M. Caldararu, N. Ionesco, Journal of Thermal Analysis and Calorimetry 64 (2001) 253-260

B1307 – Calorimetric measurements of the acidity of supported vanadium oxides prepared by ALE and impregnation

The surface acidic properties of supported vanadium oxide catalysts prepared by atomic layer epitaxy (ALE) and for comparison by a conventional incipient wetness impregnation were investigated by adsorption microcalorimetry, using ammonia as probe molecule. The acidic characteristics were strongly affected by the preparation method and the oxide supports. When using ?-Al2O3 and TiO2 as supports, the acidic character of supported vanadium catalysts always decreased compared to vanadia-free supports, whereas on weakly acidic SiO2, new acidic centres were created when depositing V2O5. The same types of acidic sites, Lewis and Brönsted, were present in all the catalysts, but those prepared by ALE showed stronger acidity. The ALE samples were more easily reduced by H2 thermo-programmed reduction and were twice as active as the impregnated samples in propane dehydrogenation to propene.
J. Keränen, A. Auroux, S. Ek-Härkönen, L. Niinistö, Thermochimica Acta 379 (2001) 233-239

B1306 – Acid sites investigation of simple and mixed oxides by TPD and microcalorimetric techniques

The present work deals with the acid properties of silica, alumina and two mixed oxides obtained by grafting silica on alumina (SA sample) or alumina on silica (AS sample). The surface acidity of the samples, of both Lewis and Bronsted type, was determined by means of microcalorimetry and temperature programmed desorption (TPD), using pyridine and 2,6-dimethylpyridine as probe molecules. Both techniques point out that the grafted mixed oxides SA and AS have acidic properties different from those of the pure alumina and silica starting supports. Some differences exist, in terms of acid sites strength distribution, between TPD and calorimetric results, which can be reasonably attributed to the different activating conditions of the samples.
A. Auroux, R. Monaci, E. Rombi, V. Solinas, A. Sarrentino, E. Santacesaria, Thermochimica Acta 379 (2001) 227-231

B1305 – Adsorption of water, methanol and acetonitrile in ZK-5 investigated by temperature programmed desorption, microcalorimetry and FTIR

The adsorption of water, methanol and acetonitrile in ZK-5 was investigated using temperature programmed desorption, microcalorimetry and FTIR spectroscopy. A multi-stage desorption in the TPD, steps in the isotherms and a stepwise decrease of the heat curves with increasing loading was found for H-ZK-5. The potassium form of ZK-5 shows a much less pronounced two step desorption behavior, pointing to the fact that K-ZK-5 is enthalpically less heterogeneous for polar molecules than the H-form. Contrary to the adsorption behavior of n-paraffins in ZK-5 the multi-stage desorption in the TPD profile and a step in the isotherm of those polar molecules can be related with the enthalpic heterogeneity of the adsorption sites in the cavities of H-ZK-5. For n-paraffins in ZK-5, however, it was found that discontinuities in the sorption behavior were determined by differences in sorption entropy. FTIR measurements with different coverage of methanol and acetonitrile on H-ZK-5 confirm the site heterogeneity of the acidic OH, but no pronounced preference between the HF or LF band could be detected.
J. Jänchen, J.H.M.C. Van Wolput, W.J.M. Van Well, H. Stach, Thermochimica Acta 379 (2001) 213-225

B1304 – Determination of the surface states of metallic clusters supported on alumina using microcalorimetry of CO adsorption

The adsorption of CO on alumina supported metal (Rh, Ru, Pt and Pd) catalysts was studied by microcalorimetry and infrared spectroscopy. The correlation of the results obtained from these two techniques provides information about the CO adsorbed species and the variations in the site energy distribution. Using these methods the nature and number of the surface sites on metal clusters, including aspects such as the presence of edge, corner or step atoms or the type of exposed crystalline planes, can be determined. Furthermore, the energetic distribution of surface sites has been shown to depend on the metal loading.
A. Maroto-Vailente, I. Rodriguez-Ramos, A. Guerrero-Ruiz, Thermochimica Acta 379 (2001) 195-199

B1303 – Calorimetric and spectroscopic measurements on the SO2 oxidation catalyst model system M2S2O7-M2SO4-V2O5/SO2(g) or Ar(g) (M=K or Cs) at 430-470°C

Calorimetric measurements have been performed on the melt-gas systems M2S2O7-V2O5 and M2S2O7-M2SO4(sat)-V2O5 (M=K and Cs) in SO2(g) and Ar(g) at 430-480°C and for mole fractions XV2O5=0-0.1. Enthalpies have been obtained for complex formation reactions as (VO)2O(SO4)44-+SO42-2VO2(SO4)23-+S2O72- for V(V) and 2VO(SO4)22-+3SO42-+SO32VO(SO4)34-+S2O72- for V(IV). Similarly enthalpies of the V(V)-V(IV) redox reactions (VO)2O(SO4)44-+SO22VO(SO4)22-+SO3 and 2VO2(SO4)23-+SO42-+SO22VO(SO4)34- could be calculated. These enthalpies of reduction compare well with those obtained by spectrophotometric measurements in the same temperature range.
G. Hatem, K.M. Eriksen, R. Fehrmann, Thermochimica Acta 379 (2001) 187-193

B1302 – Acid-base properties of supported gallium oxide catalysts

The acid-base properties of supported gallium oxide catalysts have been investigated by microcalorimetry and FTIR spectroscopy of pyridine (acidity) and CO2 (basicity) adsorption. Pyridine adsorption microcalorimetry has shown that loading supports such as y-Al2O3, TiO2, and ZrO2 with gallium oxide in a surface concentration close to the theoretical monolayer, resulted in a decrease of the surface acidity of the catalysts compared to that of the supports, while, in the case of SiO2, new Lewis acid sites were created. The number of acid sites for the supported and bulk gallium oxide catalysts was in the following order: Ga2O3/SiO2
A.L. Petre, A. Auroux, P. Gélin, M. Caldararu, N.I. Ionesco, Thermochimica Acta 379 (2001) 177-185

B1301 – Microcalorimetric and IR-spectroscopic study of the room temperature adsorption of CO2 on pure and sulphated t-ZrO2

The room temperature adsorption of CO2 on pure and sulphated tetragonal ZrO2 (t-ZrO2) was studied, in order to assess how and to what extent the acid-base properties of ZrO2 are modified by the presence of surface sulphate groups. The formation of different species, as well as their stability upon outgassing, was monitored by IR spectroscopy (2000-1000 and 2400-2300 cm-1 regions), whereas the population and the distribution of sites of different kind was quantitatively and energetically characterised by adsorption microcalorimetry. The formation of carbonate-like species was found to be a highly energetic (qads>100 kJ/mol) and irreversible process, occurring only on the (at least partially) dehydrated surface of pure t-ZrO2. Bicarbonate-like (hydrogen-carbonate) species (either of stable type) were found to form on both pure and sulphated t-ZrO2 specimens, and to be accompanied by a heat of adsorption variable in the 100-40 kJ/mol range. The presence at the surface of sulphate groups causes the basicity of the t-ZrO2 matrix to be dramatically depressed, the most basic OH- and/or coordinatively unsaturated (CUS) O2- ions being preferentially consumed by the sulphation process. Linear coordinated CO2 complexes were also found to form on CUS Zr4+ cations, the acidic strength of which increases with the extent of surface dehydration and as a consequence of the presence of charge-withdrawing surface sulphate groups.
V. Bolis, G. Magnacca, G. Cerrato, C. Morterre, Thermochimica Acta 379 (2001) 147-161

B1300 – Calorimetric and spectroscopic study of coordinative unsaturation of copper(I) and silver(I) cations in ZSM-5 zeolite – Room temperature adsorption of NH3

The room temperature (RT) adsorption of NH3 was used to probe the coordinative unsaturation of Cu(I) and Ag(I) cations highly dispersed in ZSM-5 zeolites. Adsorption microcalorimetry allowed to characterise both quantitatively and energetically the amino complexes formed at the cationic sites, as revealed by IR spectroscopy. Copper(I) sites were found to form tetra-amino [Cu(NH3)4]+ adducts, whereas silver(I) ones do form only di-amino [Ag(NH3)2]+ species. Both results are in agreement with the homogeneous chemistry of Cu(I) and Ag(I) cations. The heat of formation of the different amino-complexes was found to be comprised in the 130-50 kJ/mol interval for both kind of Me(I) sites, according to the number of ligands progressively bound and in spite of the different stoichiometry of the species formed. The adducts were found to be only partially reversible upon outgassing in the adopted conditions (303 K and p ~ 10^(-5) Torr). Two distinct, nearly equally populated families of sites were revealed in both Me(I)-ZSM-5 samples, corresponding to different coordinative unsaturations of the metal cations. EXAFS data, used to check the local environment of noble metal cations, confirmed the proposed model. In the case of Cu(I) sites, the formation of mixed amino-carbonyl complexes was also studied. The thermodynamic stability of amino- and carbonyl-like species was found not to be the same.
V. Bolis, S. Bordiga, G. Turnes Palomino, A. Zecchina, C. Lamberti, Thermochimica Acta 379 (2001) 131-145

B1299 – Site energy distribution of copper catalytic surfaces from volumetric data collected at various temperatures

Two catalysts prepared on a titanium silicate (ETS-10) matrix by loading 6 and 11 wt.% of copper were studied by employing nitrogen monoxide as adsorbate to probe the surface properties of copper centres. Volumetric isotherms of NO adsorption were collected at different temperatures (19-70°C). A thermodynamic model was applied to the isotherms in order to describe the behaviour of the NO-Cu system in terms of surface energy distribution of Cu sites. The higher loading copper sample had more energetic interaction with NO (-171
A. Gervasini, P. Carniti, A. Auroux, Thermochimica Acta 379 (2001) 95-99

B1298 – Thermal effects of the interactions of carbon monoxide with zeolites

The interactions of carbon monoxide with Lewis acid sites of zeolites were investigated using microcalorimetric and temperature programmed desorption (TPD) techniques. Carbon monoxide was adsorbed at 25°C on transition-metal ion-exchanged FAU (Y and X) and MOR type zeolites. The differential heats of adsorption (Qdif) indicate the heterogeneity of the acid sites, in all the investigated systems. The specific interactions of CO with the strongest acid sites were recognized. The results of TPD confirm that CO molecules were adsorbed on the sites of different strength.
V.M. Rakié, V.T. Dondur, R.V. Hercigonja, Thermochimica Acta 379 (2001) 77-84

B1297 – Microcalorimetric studies of O2 and C2H4 adsorption on Pd/SiO2 catalysts modified by Cu and Ag

The microcalorimetric adsorption of H2 and O2 has been employed to probe the dispersion of metals and surface composition of the bimetallic Pd-Cu/SiO2 and Pd-Ag/SiO2 catalysts. In addition, the microcalorimetric adsorption of ethylene was carried out to study the effects of Cu and Ag on the adsorption of ethylene on reduced and oxidized Pd surfaces. It was found that the addition of Cu or Ag diluted the surface Pd sites. The heats of O2 adsorption for Pd-Cu and Pd-Ag were approximately the averages between those for Pd and the second metal Cu and Ag, respectively, when the ratios of Cu/Pd and Ag/Pd are low (1:1). Moreover, the O/H ratio was found to be about 0.5 for the Pd-Cu/SiO2 (1:1) and Pd-Ag/SiO2 (1:1) samples, which was about the same for the Pd/SiO2 sample. These results suggest the enrichment of Pd on the surfaces in the bimetallic Pd-Cu/SiO2 (1:1) and Pd-Ag/SiO2 (1:1) samples. On the other hand, the initial heats of O2 adsorption for the Pd-Cu/SiO2 (1:4) and Pd-Ag/SiO2 (1:4) are approximately equal to those of the second metal Cu and Ag, respectively, revealing the enrichment of the second metals in these samples. The addition of Cu or Ag inhibited the formation of ethylidyne on the reduced Pd surface, and Ag was found to be more effective than Cu for this effect. The adsorption of ethylene on the oxidized Pd resulted in the serious oxidation of ethylene. The addition of Cu or Ag greatly reduced the oxidation of ethylene on the oxidized Pd. In this case, Cu was more effective than Ag in reducing the activity of oxygen for the oxidation of ethylene on the Pd surface.
M. Li, J. Shen, Thermochimica Acta 379 (2001) 45-50

B1273 – In situ calorimetric, structural, and compositional study of zeolite synthesis in the system 5.15Na2O-1.00Al2O3-3.28SiO2-165H2O

The synthesis of FAU zeolite was studied in situ using scanning microcalorimetry at a slow heating rate of 0.10 C/min. The scanning calorimetric heat flow (SCHF) curves showed characteristic exothermic peaks for both the precrystallization reactions and the crystallization. Combined with complementary characterization techniques, the structural and chemical changes in the zeolite synthesis system were identified and correlated with the SCHF peaks. Two mixtures of the same composition (5.15Na2O-1.00Al2O3-3.28SiO2-165H2O) but prepared from different silica sources (colloidal silica vs silicate solution) for the syntheses of FAU zeolite were examined. A cyclic or oscillatory pattern for precrystallization reactions was observed for the first time. This precrystallization evolution pattern indicates the stepwise precrystallization reactions that may result in significant inhomogeneity of the Si/Al ratio in the microscopic domains of the amorphous precursor. The existence of the compositional inhomogeneity is consistent with the occurrence of the LTA zeolite impurity (Si/Al = 1.0) when colloidal silica is used but not when solution of dissolved silica is used. A small energetic driving force for the crystallization (H = -2.1 ± 0.1 kJ/mol on TO2 basis of the zeolite product) has been directly measured. The integral enthalpy change for the precrystallization reactions varies greatly depending on the nature of the starting materials. The implications of the thermodynamic results in zeolite synthesis are also discussed.
S. Yang, A. Navrotsky, B.L. Phillips, J. Phys. Chem. B. 104 (2000) 6071-6080

B1272 – An in situ calorimetric study of the synthesis of FAU zeolite

Synthesis of FAU zeolite from a mixture of silicate and aluminate solutions (5.15Na2O-1.00Al2O3-3.28SiO2-165H2O) was studied using an in situ calorimetric method at a heating rate of 0.1°C/min. The scanning calorimetric curve provides a coherent and consistent recording of the synthesis process. At low temperature (25-66°C), the calorimetric curve drifts slightly in the endothermic direction. Chemical analysis shows a slight increase in the dissolution of the amorphous gel/solid phase with increasing temperature in this period. The onset of the exothermic peak at 66.7°C is suggested to signal the beginning of the nucleation/crystallization process. Formation of the FAU structure is an exothermic event and the associated heat effect was directly measured, -2.38±0.06 kJ/mol based on TO2 (T=Si or Al) or -457±12 kJ/mol based on the unit cell formula of the FAU product, Na91.Si105Al91O384.277H2O. The integral heat for the crystallization by calorimetry agrees well with the X-ray diffraction (XRD) or NMR crystallinity of the solid phase. At the early stages of crystallization (integral heat <0.1% of the total) the compositional changes in solid and solution were similar to those in the pre-crystallization period. The FAU phase was slightly richer in Al than the gel/solid amorphous precursor. The abrupt drop of the soluble Al concentration during the rapid crystallization period indicated the direct participation of the soluble aluminosilicate species in the crystal growth. The crystalline phase could be observed using XRD, NMR or IR only significantly after the onset of the calorimetric peak because the mass fraction of the nuclei/crystals in the solid phase was initially too low to be detected by the former methods. This demonstrated the high sensitivity of the calorimetric method.
S. Yang, A. Navrotsky, B.L. Phillips, Microporous and Mesoporous Materials 46 (2001) 137-151

B1257 – Promotion effect of coating alumina supported palladium with sodium hydroxide on the catalytic conversion of nitric oxide

The catalytic conversion of NO into nitrogen and oxygen over different Pd/Al2O3 catalysts was studied in a flow reactor. The catalytic activity of the catalysts was profoundly promoted by pre-coating the alumina support with NaOH before the palladium impregnation. Observed nitrogen yield was raised from 15% to 60% at a temperature of 900 K by coating a 4.8% Pd/Al2O3 catalyst with 13% NaOH. A simultaneous thermogravimetric-analysis and differential-scanning-calorimetry (TGA-DSC) characterization on adsorptions of NO indicated that some NO molecules were strongly adsorbed and possessed a higher enthalpy of adsorption (140 kJ (mol NO)-1) than Pd/Al2O3 (114 kJ (mol NO)-1). A temperature-programmed-desorption (TPD) study further indicated that some strongly adsorbed NO molecules may stay on the NaOH promoted catalysts till the system temperature was raised over 950 K. The observed increase in N2 yield from NaOH promoted Pd/Al2O3 catalysts was therefore attributed to the adsorption of NO on the strongly adsorbed sites.
C-B. Wang, J-G. Chang, R-C. Wu and C-T. Yeh, Applied Catalysis B: Environmental 17 (1998) 51-62

B1256 – Alkylation of benzene by propene on a series of Beta zeolites : toward a better understanding of the mechanisms

Alkylation of benzene with propene has been investigated on a series of H-Beta zeolites with different Si/Al ratio: 10, 35 and 66, using different techniques such as FTIR, 13C NMR and catalytic testing. It has been shown that H-Beta zeolite (Si/Al ratio=10) is a very active catalyst for this reaction with propene, but it leads also to fast oligomerization even at lower reaction temperatures. 13C NMR experiments have demonstrated for the first time that the reaction of alkylation is already complete at -80°C on these catalysts. Dealuminated H-Beta zeolites are less active but lead to less aromatic by-products (especially n-propylbenzene) and the deactivation due to the coke formation is reduced. The high ratio of benzene/propene favors the formation of cumene and suppresses the oligomerization of propene. Triisopropylbenzene (TIPB) can also be formed at low temperatures (<100°C) and then is transformed by transalkylation into diisopropylbenzene (DIPB) at higher temperatures (>130°C). The present work reveals that the alkylation of benzene by propene occurs via an Eley-Rideal type mechanism. The apparent activation energy for this reaction has been determined and shows to decrease as the Si/Al ratio of H-Beta zeolites increases. The relatively low apparent activation energies obtained for this reaction on a series of H-Beta zeolites studied suggests that it exists a diffusion step of reactants and products between the silanols of the Beta zeolite.
S. Siffert, L. Gaillard and B-L. Su, Journal of Molecular Catalysis A: Chemical 153 (2000) 267-279

B1255 – Characterization of the Bronsted acid properties of H(Na)-Beta zeolite by infrared spectroscopy and thermal analysis

Infrared spectroscopy and thermal analysis have been used to characterize the Bronsted acidity, the hydroxyl groups of H-Beta zeolite, and the interaction of hydroxyls with benzene molecules. After pretreatment under dry oxygen and then under vacuum at 723 K, three hydroxyl groups at 3,789, 3,745, and 3,612 cm-1, superimposed on a broader absorption (3,800-3,200 cm-1), have been detected. These three peaks are assigned to species near to one or more groups generated when leaves the framework, terminal silanol groups, and framework bridged species, respectively. The broader absorption band should be attributed to the internal silanol group. The present work shows that the hydroxyl group at 3,789 cm-1 can be generated also after a mild treatment. This observation is contrary to previously published results by other research groups. Furthermore, the present study shows that all three hydroxyl groups situated at 3,789, 3,745, and 3,612 cm-1 can interact completely with benzene. This is in contrast with the case of pyridine. It seems that some framework protons (or cations), located in the small cavities and being initially inaccessible, can be attracted toward the 12-R channels in the presence of benzene and finally become accessible for benzene. The acid strength of each hydroxyl group is evaluated by the shift of the hydroxyls upon their interaction with benzene and is compared to other proton zeolites such as HZSM-5, HY, and HEMT zeolites. It indicates that the framework-bridged groups of -Beta zeolite have an intermediate Bronsted acidity. The amount of Bronsted acid sites as well as the total adsorption capacity for benzene have been determined from the study of the changes of the absorbance of the out-of-plane vibrations with benzene coverage. The number of TEA species associated with tetrahedral aluminum and with structural defects or ions has been also determined using thermobalance coupled with ammonia titration.
B-L. Su and V. Norberg, Zeolites 19 (1997) 65-74

B1230 – High-temperature differential scanning in situ. Calorimetric study of the mechanism of catalytic processes.

The general principles of the calorimetric studies of nonequilibrium gas-solid systems and applications various of methods usually referred to as differential scanning calorimetry to heterogeneous catalysis are considered. In situ differential scanning calorimetry is used to investigate the dynamic thermochemical state of the systems. Along with its traditional application (phase transitions and chemical reactions in catalysts and their solid precursors, the qualitative and quantitative analysis of the phase composition of the samples, and the characterization of energetic nonuniformity of solid surfaces), the differential scanning calorimetry may also be used to study the mechanisms of complex catalytic processes: the construction of thermochemical properties vs. reactivity diagrams, the discrimination of the mechanisms of the heterogeneous activation of gaseous molecules, the evolution of active surface sites and states of solid bulk, and the construction of kinetic models for complex heterogeneous-homogeneous processes.
M.Yu. Sinev and V.Yu. Bychkov, Kinetics and Catalysis 40 (1999) 819-835

B1204 – Calorimetric study of the acidity and interface effects of tin dioxide layers deposited on another metal oxide.

Samples with various amounts of tin oxide were prepared by impregnating -Al2O3, TiO2(anatase), SiO2, ZrO2 and MgO with tin tetrachloride or tributyltin acetate solutions. After drying and calcination, the samples were characterized by chemical analysis, XRD and BET measurements. Ammonia adsorption microcalorimetry was used in order to determine the number, strength and strength distribution of surface acid sites. The influence of the adsorption temperature, evacuation temperature, amount of SnO2 deposited and of the nature of the support on the adsorption properties were studied.
D. Sprinceana, M. Caldararu, N.I. Ionescu, A. Auroux, Journal of Thermal Analysis and Calorimetry 56 (1999) 109-115

B1192 – Microcalorimetric studies of the surface reactivity of pollutant gas atmospheres on supported SnO2 and Ga2O3 catalysts.

The surface properties of gallium oxide and tin dioxide supported on alumina or titania have been studied by adsorption microcalorimetry. The differential heats of adsorption of various pollutant adsorbates such as sulfur dioxide, nitrogen monoxide, nitrogen dioxide and also ammonia were measured on these catalytic surfaces. NH3, SO2, NO2 are strongly adsorbed while NO is only physisorbed. The supported Ga2O3 samples show a slight decrease in acidity as probed by ammonia adsorption, compared to alumina or titania. The addition of SnO2 decreases the number of strong acid sites but creates a few weak and medium strength acid sites on alumina and does not modify the acidity of titania. In all cases, the basicity, probed by SO2 adsorption, is very strongly affected by the deposition of Ga2O3 or SnO2. The differential heats of NO2 adsorption remain nearly constant on all samples. The heats of adsorption are discussed as a function of the coverage and of the amount of guest oxide.
B. Gergely, A. Rédey, C. Guimon, A. Gervasini, A. Auroux, Journal of Thermal Analysis and Calorimetry 56 (1999) 1233-1241

B1184 – Calorimetric study of the acidity of a new family of mesoporous catalysts.

Thermally stable mesoporous aluminophosphates (AIPO) and silicoaluminophosphates (SAPO) were prepared at room temperature in the presence of a cationic surfactant and an organic base. These materials possess high surface areas and regular mesopores of approximately 35 diameter. By contrast to microporous crystalline aluminophosphate molecular sieves, mesoporous compounds are amorphous and characterized by Al/P ratios greater than 1. These particularities are responsible for a strong Lewis acidity, as evidenced by ammonia adsorption microcalorimetry. Mesoporous materials are more acidic than the microporous analogues and the amount of strong acid sites increases with the silicon content.
S. d'Arbonneau, A. Tuel, A. Auroux, Journal of Thermal Analysis and Calorimetry 56 (1999) 287-296

B1172 – Adsorption of a polar or a non-polar chloroalkene on a ZSM-5 zeolite at 298 K.

The physisorption of trichloroethylene and tetrachloroethylene on ZSM-5 (Si/Al = 339) zeolite was investigated at 298 K using thermogravimetry, differential microcalorimetry and X-ray diffraction. The zeolite always undergoes a monoclinic-orthorhombic structural change during the adsorption of the first molecules. An alignment of the polar trichloroethylene molecules inside all the channels of the zeolite is proposed to account for the experimental results. A phase transition of the non-polar tetrachloroethylene is suggested to produce the stepped isotherm, the steep rise in the heat curve and the high increase in the mobility of the molecules for the loading of 4 molecules per unit cell.
F. Bouvier, G. Weber, Journal of Thermal Analysis Vol 54 (1998) 881-889

B1168 – Calorimetric probes of carbon dioxide sorption in bisphenol-A based polymers.

We present direct measurements of the partial molar enthalpy of carbon dioxide sorption in a family of structurally related bisphenol-A based polymers. Polymers included in this study are: bisphenol-A polycarbonate, tetramethyl polycarbonate, tetrachloro polycarbonate and tetrabromo polycarbonate. All samples were conditioned at 300 psig prior to measurement. Enthalpy changes were determined using a Setaram C80D microcalorimeter equipped with high pressure cells. The magnitude of the heat of sorption does not correlate well with polymer free volume, gas solubility or gas partial molar volume. However, the values are consistent with heats of sorption calculated from the temperature dependence of solubility. The results suggest that free volume regions are not uniformly accessible; occupation of some free volume regions requires unfavourable deformation of the glassy polymer matrix. The measured heat of sorption represents an energetically weighted average of those free volume regions which are occupied.
T. Banerjee and G.G. Lipscomb, Polymer 38 (1997) 5807-5813

B1167 – Study of the interaction of a chloroalkene on a ZSM-5 zeolite at 298 K.

F. Bouvier, S. Maure, G. Weber, O. Bertrand, Fondamental of Adsorption (1998) 171-176

B1160 – Processes of ammonia adsorption in gallium zeolites as studied by microcalorimetry

In adsorption calorimetric studies, it is necessary to analyse the obtained calorimetric and volumetric data in relation to coverage or number of sites. For this purpose, procedures have been developed to relate quantitative measurements of heat liberation to the different processes which are taking place as the amount of adsorbed ammonia increases, due to reversible and irreversible adsorption. In order to describe the relative contributions of these two phenomena (physical and chemical adsorption) to volumetric isotherms as well as to calorimetric thermograms, they have been modeled and chemisorption was separated from physisorption. Calorimetric and volumetric measurements performed on H-[Ga]-BEA and H-[Ga]-MFI zeolites have provided experimental data to validate the theoretical models. The acidity of the gallium samples has been compared with that of the corresponding aluminum samples.
B. Ducourty, M.L. Occelli, A. Auroux, Thermochimica Acta 312 (1998) 27-32

B1159 – Microcalorimetric and spectroscopic studies of the acidic- and physisorption characteristics of MCM-41 and zeolites

The acidic and sorption properties of Al containing MCM-41 molecular sieves in comparison with relevant FAU and MFI zeolites were investigated by n-hexane, benzene, acetonitrile, and water adsorption by means of microcalorimetry, isotherm measurements as well as FTIR and 1H MAS NMR techniques, using acetonitrile or chloro-acetonitrile as probes. MCM-41 shows relatively weak Bronsted acidity, comparable with the LF proton of HY. The strongest sites are Lewis centres according to the strongest heats of adsorption and the corresponding characteristic CN frequencies of acetonitrile in contrast to the HY or the dealuminated form of HY. MCM-41 shows a physisorption behaviour of a well-defined mesoporous molecular sieve, which makes it favourable as a model substance. Whereas, the heats of adsorption of acetonitrile are mainly influenced by a specific interaction on the acidic sites in the meso- and microporous molecular sieves, the adsorption heat of a non-polar molecule like n-hexane is determined by the pore size or density of those materials. However, a pore-size effect on the adsorption heats of acetonitrile in acidic molecular sieves has to be taken into account while employing those heats as a measure of acidic strength. The contribution of the pore size governed dispersion interaction in MCM-41 is ca. 15 kJ/mol smaller than that in the narrow channels of MFI.
J. Jänchen, H. Stach, M. Busio, J.H.M.C. van Wolput, Thermochimica Acta 312 (1998) 33-45

B1158 – Effect of catalyst deactivation on the acid properties of zeolites used for isobutane/butene alkylation

Coke formation during the isobutane/butene alkylation reaction over zeolites decreases the acidity and acid strength of the catalysts. Microcalorimetric measurements of the differential heat of pyridine adsorption and FTIR spectroscopy of adsorbed pyridine were used to probe the changes in the acid properties caused by the deactivation processes. Specifically, fresh and deactivated commercial acid catalysts such as REY, USY, and Beta zeolite were studied. The adsorption microcalorimetry and FTIR spectroscopy results demonstrated that USY has the strongest acid sites (both Bronsted and Lewis) and the highest concentration of strong sites followed by REY and then by Beta zeolite. This order is the opposite of that observed for the alkylation catalytic performance of these zeolites. In particular, it seems that having a high concentration of strong Lewis sites promotes catalyst deactivation. The deposits formed during deactivation have a strong paraffinic character, but evidence of olefinic species is also observed. The degree of unsaturation of the surface species formed increases from Beta to USY zeolite, implying that the presence of a high concentration of strong Lewis-acid sites promotes the formation of unsaturated compounds. Bronsted sites with intermediate acid strength appear to be the appropriate sites for maintaining good alkylation catalytic performance. The best catalytic performance and the slowest deactivation were achieved with Beta zeolite, followed by REY and USY with low sodium content. Only butene isomerization was observed for USY with high sodium content. For the active catalysts, the alkylation global reaction route dominates initially, but the amount of alkylation products decreases as the catalyst starts deactivating when oligomerization predominates; and, finally, the catalyst loses most of its activity and isomerization is the only reaction observed. The product distribution obtained suggests that, instead of authentic alkylation, the initial prevalent mechanism is polymerization followed by beta-scission. Two deactivation models are proposed to explain the deactivation. The direct obstruction of the alkylation active sites by irreversible adsorption of coke or coke precursors and the indirect obstruction of the active sites by pore blocking or pore filling.
F.A. Diaz-Mendoza, L. Pernett-Bolaño, N. Cardona-Martinez, Thermochimica Acta 312 (1998) 47-61

B1157 – Surface acidity of metal oxides. Combined microcalorimetric and IR-spectroscopic studies of variously dehydrated systems

The systematic use of CO adsorption at room temperature as a probe for (strong) Lewis acidity at the surface of a number of non-d/d0 metal oxides of interest in catalysis is illustrated. The advantages of the combined use of adsorption microcalorimetry and IR spectroscopy in giving an exhaustive picture of the distribution of acid surface sites are stressed. The influence of the chemical nature (TiO2, ZrO2, HfO2 and Al2O3) and of the structure (monoclinic/tetragonal for ZrO2 and ?-/d,?- phase for Al2O3) of the metal oxide, as well as the dehydration degree of the surface and the presence of anionic (sulfates for zirconia) or cationic (ceria for alumina) surface dopants were considered. The blue shift of the stretching frequency of adsorbed CO and the adsorption enthalpy were measured. In the case of the group IV metal oxides the two parameters were found to be correlated, whereas in the case of pure Al2O3 no correlation was found. The peculiar behavior of alumina was interpreted on the basis of different processes occurring at the CO/Al2O3 interface. An endothermic reversible reconstruction of the surface was supposed to occur upon adsorption, leading to exceptionally low heat values. The presence of small amounts of cations, other than Al3+, in the alumina matrix seemed to inhibit this effect.
V. Bolis, G. Cerrato, G. Magnacca, C. Morterra, Thermochimica Acta 312 (1998) 63-77

B1156 – Energetics of H2 and O2 adsorption on Ir/y-Al2O3 and Ir/SiO2 catalysts. Dependence on support and on metal particle size

The adsorption of hydrogen and oxygen on Ir/SiO2 and Ir/Al2O3 catalysts of various metallic percentages and different metal particle sizes has been studied by adsorption microcalorimetry. The hydrogen adsorption stoichiometries lay between 1.1 and 2.4, depending on the support and on degree of dispersion. The variation of hydrogen adsorption heat with amount adsorbed revealed significant differences in surface heterogeneity between the various samples. The dependence of hydrogen adsorption stoichiometry and differential heat of adsorption vs. coverage curves on support and on particle size may be related to crystallite size and shape, and to differences in metal-support interaction. On the contrary, oxygen adsorption stoichiometries and differential heat of adsorption vs. coverage curves were very similar for all samples. The amount of oxygen adsorbed at the completion of the monolayer, clearly identified in the differential calorimetric isotherms, coincided with the amount of superficial iridium as determined by a volumetric method.
J.M. Guil, A. Pérez Masia, A. Ruiz Paniego, J.M. Trejo Menayo, Thermochimica Acta 312 (1998) 115-124

B1148 – Experimental study at the solid/liquid interface : enthalpies of wetting of several liquids onto active carbon.

Enthalpies of wetting of several pure liquids onto active carbon were measured at 298.15 K with a quasi-isothermal microcalorimeter Setaram MS 80 II. New measuring cells with three independent cavities of about 15 cm3 were created. The advantage of this new method is the high weight-in of active carbon and a reduced time per measurement for reaching a constant baseline. Experiments were carried out with n-alkanes, 1-alkanols, cyclohexane, 2,2,4-trimethyl-pentane (isooctane) and water. The experimental results for the enthalpy of wetting show a dependence of the geometric heterogeneity of the active carbon and the polarity of liquids.
P. Ulbig, T. Friese, S. Schulz, J. Seippel, Thermochimica Acta 310 (1998) 217-222

B1127 – Microcalorimetric study of the acidity and basicity of Ni/SiO2 catalysts modified by metallic additives Fe, Co, Zr and Ce

The acidity and basicity of silica-supported nickel catalysts modified by metallic additives such as Fe, Co, Zr and Ce have been determined by adsorption microcalorimetry. These catalysts have been tested in the catalytic reforming of methane with carbon dioxide. The results indicate that the metallic additives modify noticeably the acidity of the Ni/SiO2 catalysts, the acidity increasing in the order: Ni-Ce < Ni < Ni-Co < Ni-Fe < Ni-Zr. Moreover, it was demonstrated that the most active catalyst in the CH4 + CO2 reaction is the least acidic, namely, Ni-Ce/SiO>
O. Cherifi, M.M. Bettahar, A. Auroux, Thermochimica Acta 306 (1997) 131-134

B1125 – Calorimetric study on interaction of dioxygen with alumina supported palladium.

Pd/Al2O3 samples of various palladium loadings were prepared with the incipient-wetness method. With an increase in the palladium loading, the average diameter (d) of palladium crystallites on these samples was estimated from chemisorption of hydrogen to vary from 10 to 80 Å. Also, the phenomena of oxidizing these dispersed palladium crystallites with dioxygen were studied by a simultaneous TG-DSC instrument. The extent of oxidation was found to increase in three steps with temperature: adsorption on the surface of Pd crystallites at ambient or lower temperatures, penetration of oxygen into the sublayer when raising the temperature over 300 K, and formation of palladium oxide structure at 800 K. The heat evolved during oxygen adsorption on palladium crystallites depended on their average diameter (d) and displayed a relationship of -Qad [kJ (mol O2)-1] = 373 - 14d (nm). Evolved heat upon palladium oxidation decreased with the extent of oxidation (No/Npd ratio in the product). Upon the complete oxidation at 800 K, a diameter independent ?fH°298(PdO) of - 187 ± 2 kJ (mol O2)-1 was subsequently obtained. This value differs significantly from the literature ?fH°298(PdO) values (- 220 kJ (mol O2)-1) obtained from the Clausius-Clapeyron equation. The discrepancy should have resulted from a partial desorption of oxygen from PdO during measurement.
Y-S. Ho, C-B. Wang and C-T. Yeh, Journal of Molecular Catalysis A : Chemical 112 (1996) 287-294

B1121 – Acidity characterization by microcalorimetry and relationship with reactivity.

In the area of acid catalysis, adsorption microcalorimetry studies have alloweda significant insight in surface studies under certain experimental conditions.Consideration is given to the interpretation of the heat evolved when a basicprobe molecule is adsorbed on the surface of crystalline or amorphoussilica-aluminas. In particular, the number and strength of acid sites arediscussed as functions of lattice structure, concentration and nature offramework cation and basicity of the probe molecules.
A. Auroux, Topics in Catalysis 4 (1997) 71-89

B1117 – Comment mettre en évidence expérimentalement des transitions de phases dans le cas des systèmes {zéolithe/adsorbat} ?

F. Bouvier, G. Weber, Calo. & analyse ther. vol 28 p 119-124

B1101 – Heats of chemisorption of n-aliphatic alcohols on alpha-Al2O3 at 25-200°C. A thermokinetic study.

A differential microcalorimeter (E. Calvet) was used to study the processes of adsorption of five aliphatic alcohols (C1-C5) on -Al2O3 at 25, 50, 100, 150 and 200°C. In particular, the importance of the thermokinetic study of the chemisorption of such alcohols at different experimental temperatures was demonstrated, with regard to the variations in the thermokinetic parameters (tmax, t1/2 and t0) and the evolution of the alcohol vapor pressure on the adsorbent during the adsorption process. It was concluded that: a) all the heat emission peaks of alcohol adsorption have the same rounded shape at 25°C; b) on passing from methanol to 1-pentanol, the area of the adsorption peaks increases as the chain length or molecular weight increases; c) on passing from 25 to 200°C, the shape of the adsorption peaks becomes more pointed.
P.F. Rossi, Journal of Thermal Analysis 49 (1997) 627-634

B1096 – Differential calorimetric enthalpies of adsorption of p-xylene and m-xylene on Y faujasites at 25°C.

The differential enthalpies of adsorption ofp-xylene andm-xylene on NaY, KY and BaY zeolites were measured by isothermal calorimetry coupled with isothermal volumetry at 25°C. Whatever the zeolite, the enthalpies of adsorption ofp-xylene andm-xylene at low filling were of the same order of magnitude. They did not show significantly the effect of the dipolar moment ofm-xylene. Their absolute values varied in the sequence Q0(pX/NaY)
M-H. Simonot-Grange, O. Bertrand, E. Pilverdier, J-P. Bellat, C. Paulin, Journal of Thermal Analysis 48 (1997) 741-754

B1088 – Microcalorimetric measurements of differential heats of adsorption on reactive catalyst surfaces.

Techniques are presented for measurement of differential heats of adsorption on reactive catalyst surfaces using heat-flux calorimetry. Samples are prepared ex-situ in ultra-pure flowing gases and then sealed in Pyrex capsules. Special calorimetric cells are employed to break the sample capsule after thermal equilibration of the sample with the calorimeter. In this manner the clean sample is exposed rapidly to the adsorbing gas, minimizing surface contamination. Initial heats of CO and H2 adsorption at 403K on Pt/SiO2 catalysts obtained using the present technique (135 and 100 kJ/mol. respectively) were in agreement with results reported in the literature using standard calorimetric procedures. Initial heats measured in this study for CO adsorption at 308 K on reduced Ni powders (120 kJ/mol) and on nickel samples containing metallic potassium (200 kJ/mol) corresponded to values in the literature from ultrahigh vacuum studies of CO adsorption on Ni single crystal surfaces. The initial heat of N2 adsorption at 453 K on reduced iron determined in this study (200 kJ/mol) was in agreement with results obtained in ultrahigh vacuum measurements of metallic iron single crystal surfaces. These results, for catalyst systems that are sensitive to traces of oxygen-containing species, provide strong evidence that the experimental techniques employed in the present study allow clean metallic surfaces to be maintained during microcalorimetric adsorption studies.
B.E. Spiewak, J.A. Dumesic, Thermochimica Acta 290 (1996) 43-53

B1068 – Modelling of the experimental phenomena occurring during simultaneous TG-DSC measurements of water desorption.

To prove the given model, it was applied to investigations of the desorption process of adsorbed water on zeolites by simultaneous TG-DSC measurements. It was found that with the help of this model, by integration of the corresponding DSC curves, suitable enthalpy values could be obtained even for unfavourable shapes of the baseline.
K. Sigrist, H. Stach, Thermochimica Acta 278 (1996) 145-156

B1053 – Energetics of methane adsorption on microporous activated carbons.

The influence of microporous carbon surface oxidation on energetics of methane adsorption at 308 K is discussed. Obtained adsorption heats and integral molar entropies of the adsorbate show that microporous carbon surface oxidation changes the methane adsorption process. This is probably resulted by the existence of an endothermic effect during adsorption in oxidized carbon micropores.
G. Rychlicki, A.P. Terzyk, Journal of Thermal Analysis 45 (1995) 1183-1187

B1040 – Commensurate freezing of n-Alkanes in silicalite.

W.J.M. van Well, J.P. Wolthuizen, B. Smit, J.H.C van Hooff, R.A. van Santen, Angewandte Chemie. International edition in English 34 (1995) 2543-2544

B1018 – Microcalorimetric and catalytic studies of the acidic character of modified metal oxide surfaces. 1. Doping ions on alumina, magnesia, and silica.

Microcalorimetry of ammonia and sulfur dioxide adsorption and catalytic reaction of 2-propanol conversion have been used to study the effects on the acidhase properties of adding small amounts of ions (Ca2+, Li+, Nd3+, Ni2+, s04'-, Zr''+) on y-alumina, silica, or magnesia surfaces. It was found that the modification of y-Al2O3 surface properties with small amounts of the above ions changed moderately its amphoteric properties. More substantial changes were observed on magnesia which consisted in formation of centers of moderate and weak basic strength. The number of acidhase centers on doped silica was strongly affected by the presence of introduced ions. The catalytic test of 2-propanol conversion led to results in agreement with the acidity determination performed by adsorption microcalorimetry. The intermediate acidity strength played a central role in 2-propanol dehydration. We proposed a classification of the modified catalysts according to an acidityhasicity scale defined by the specific effect of ions. The acidity of the catalysts correlated with the chargehadius ratio and with the generalized electronegativity of the doping ions. The basicity correlated with the partial oxygen charge of the corresponding oxides.
A. Gervasini, G. Bellussi, J. Fenyvesi, A. Auroux, Journal of Physical Chemistry 99 (1995) 5117-5125

B1012 – Energy distribution of surface acid sites of metal oxides

The acid site strength distributions of y-Al2O3, BeO, Nb2O5, TiO2, WO3, and ZrO2 surfaces were evaluated starting from volumetric and calorimetric experimental data of ammonia adsorption collected at 80 and 150°C. A mathematical model was employed to describe the behavior of the adsorbate-adsorbent system. The model took into account a discrete inhomogeneity of the surface. A fitting procedure applied to both the isotherms and the integral heat curves of ammonia adsorption, at the two above temperatures, permitted the determination of the thermodynamic parameters characteristic of the different types of site. The number, nmax,i, the adsorption equilibrium constant, bi, as well as a new parameter termed the "half-coverage temperature at unit pressure," T°1/2,i, of each type of acid site were obtained. All the oxides showed a significant amount of acid sites with ammonia enthalpy of adsorption ?aHi at -40 kJ/mol corresponding to hydrogen-bonded ammonia. Three types of more energetic sites, with ?aHi ranging from -280 to -160 kJ/mol, were found for y-Al2O3, Nb2O5, TiO2, and ZrO2. Sites with ?aHi of -280 and -200 kJ/mol were found for BeO and WO3. Mean molar adsorption entropies were also determined, and the values obtained are typical of immobile or localized adsorption.
P. Carniti, A. Gervasini and A. Auroux, Journal of Catalysis 150 (1994) 274-283

B1004 – Microcalorimetric and infrared studies of the acid-base properties of V2O5/y-Al2O3 catalysts

The acid-base properties of V2O5 /y-Al2O3 catalysts were characterized by ammonia, pyridine and sulphur dioxide adsorptions using microcalorimetry and diffuse reflectance Fourier transform Ir spectroscopy (DRIFT). For vanadium content less than 10 wt.-% V2O3 (4.9 ?mol(V2O5) m-2), the vanadium cations were found to be well spread as vanadate compounds over alumina. Such vanadate species developed Bronsted and Lewis-type acidity as shown by a DRIFT spectroscopy study of pyridine adsorption, but did not exhibit a basic character. Sulphur dioxide adsorption allowed to differentiate a vanadate layer from free alumina. Ammonia and sulphur dioxide adsorptions also showed that at low vanadium coverage, a large part of the vanadate layer was bound to acid-base pairs of alumina. Vanadium pentoxide crystallites were detected at less than complete monolayer coverage with vanadate compounds, but did not contribute to the development of the acidic surface character. At low vanadium coverage, ( <3 wt.-%V2O5, 1.2 ?mol(V2O5) m-2), the acidic character of the V2O5/y-Al2O3 catalysts is ascribed to vanadium-free alumina, whereas it is largely attributed to vanadate compounds at higher vanadium coverage.
J. Le Bars, J. C. Védrine, A. Auroux, S. Trautmann and M. Baerns, Applied Catalysis A: General 119 (1994) 341-354

B0976 – Correlation between initial heats of adsorption and structural parameters of molecular sieves with different chemical composition : a calorimetric study

H. Stach, K. Fiedler, J. Janchen, Pure & Appl. Chem. 65 (1993) 2193-2200

B0975 – Adsorption calorimetric measurements and 27 Al DOR NMR studies on the molecular sieve AlPO4-18

Highly crystalline samples of the chabazite-related aluminophosphate AlPO4-18 (AEI) have been prepared and characterized by adsorption measurements as well as by *7Al double rotation (DOR) NMR studies. Whereas the heat curves and isotherms of n-paraffins on AEI show the common feature for adsorption on nonpolar molecular sieves with a given pore dimension, methanol gives an unusual heat curve with a deep minimum for a loading >4 molecules per cavity. This corresponds to the extended low-pressure hysteresis loop of the isotherm which is absent in SAPO-34. In accordance with the structure determination and Rietveld refinement of the as-synthesized AEI, three crystallographically inequivalent A1 positions including one pentacoordinated A1 could be detected and assigned by 27Al DOR NMR. Calcination as well as the adsorption of polar molecules results in a structure change. While water and ammonia generate octahedrally coordinated Al, methanol gives only AIV as has been found for the template-containing sample. The methanol adsorption has been studied in more detail. It has been found that the formation of the AP requires more than one methanol molecule per All site. This process occurs for a loading between one and four molecules per cavity; it is isobaric and compares to a hydration process. Two additional molecules can be accommodated in the AEI cavity which seems to be related to the second step of the methanol isotherm and the extended low-pressure hysteresis loop which is absent in the isotherm of water. This is accompanied by another reversible structure change resulting in four NMR lines for the six different A1 positions in the double 6-ring, the secondary building unit of the AEI.
J. Janchen, M.P.J. Peeters, J.W. de Haan, L.J.M. van de Ven, J.H.C. van Hooff, I. Girnus, U. Lohse, Journal of Physical Chemistry 97 (1993) 12042-12046

B0974 – CoAPO molecular sieve acidity investigated by adsorption calorimetry and IR spectroscopy

J. Janchen, M.P.J. Peeters, J.H.M.C van Wolput, J.P. Wolthuizen, J.H.C. Van Hooff, U. Lohse, Journal of the Chemical Society Faraday Transactions 90 (1994) 1033-1039

B0973 – Acidic properties of metal substituted aluminophosphates studied by adsorption calorimetry and IR spectroscopy

J. Jänchen, M.J. Haanapen, M.P.J. Peeters, J.H.M.C. van Wolput, J.P. Wolthuizen, J.H.C. van Hooff, Studies in Surface Science and Catalysis 84 : Zeolites and related microporous materials : State of the art (1994) 373-380

B0972 – Adsorption of polar molecules on the large pore molecular sieve VPI-5

J. Janchen, H. Stach, P.J. Grobet, J.A. Martens, P.A. Jacobs, 9th International Zeolite Conference Montreal (1992) 21-27

B0948 – Characterization of siliceous MFI-type zeolites containing tetra-, tri-, and dipropylammonium fluoride species

Highly siliceous MFI-type zeolites containing tetra-, tri-, and dipropylammonium fluoride species, synthesized in the presence of fluoride ions, were characterized by powder X-ray diffraction t.g., d.s.c., and high-resolution solid-state n.m.r. of 13C and 29Si. The occupation of the channels by the different organic species could be elucidated by considering the refined unit cell parameters. In the case of, particularly, the dipropylammonium fluoride-containing sample the organic molecule is found to be located preferentially in the zigzag channels, in agreement with the results of the other techniques.
J. Patarin, M. Soulard, H. Kessler, J-L. Guth and J. Baron, Zeolites 9 (1989) 397-404

B0932 – Heat of chemisorption of 1-propanol on alpha-Al2O3 at 25-200°C. A microcalorimetric study

We have studied by means of differential mieroealorimetry the adsorption process of 1-propanol on alpha-Al2O3 at the temperatures of 25, 50, 100, 150 and 200°C respectively. Both amounts of adsorbed alcohol and heats released decrease as the temperature of adsorption increases. At very low coverage, the high value of differential heat shows a strong irreversible chemisorption on active sites (Lewis acid sites) (qdiff > 200 kJ.mol-1). Moreover, we carried out some thermokinetic investigations on heat emission peaks at different coverage degree (different equilibrium pressure of 1-propanol vapour as a function of time) and at different temperatures of adsorption, at same coverage.
P.F. Rossi, M. Bassoli, G. Oliveri, F. Guzzo, Journal of Thermal Analysis 41 (1994) 1227-1235

B0919 – TG and DSC investigation of the dehydration of the extra large pore aluminophosphate molecular sieve VPI-5 and related materials

The dehydration of a series of VPI-5 and H3 samples, synthesized under various conditions, as well as the solid state transformation of VPI-5 to A1PO4-8 have been investigated using combined TG-DTG-DSC and high-resolution solid state 31P-NMR.The TG curves show a quasi-continuous release of water, the total loss being characteristic for each sample. Complete dehydration is achieved when the samples are heated from 20°C to about 150°C at various heating rates. Besides the main dehydration effect, several weak endothermic peaks are observed. These generally non-reproducible modulated peaks, recorded at high heating rates, are presumably due to the interactions of the water molecules leaving the channels of VPI-5 with the randomly positioned fragments stemming from the destruction of the water triple helix assemblage. The non-isothermal kinetic parameters of the dehydration have been evaluated from the TG and DTG curves recorded at low heating rates.
E. Segal, L. Maistriau, E.G. Derouane, Z. Gabelica, Journal of Thermal Analysis 41 (1994) 701-712

B0917 – On the interaction between ammonia and SAPO-5

New data are presented concerning the low-temperature adsorption of ammonia on SAPO-5, the TPD of the low-temperature-adsorbed ammonia, and the high-temperature interaction of ammonia with the SAPO-5 framework.
E. Segal, I. Ivanova, E.G. Derouane, Thermochimica Acta 231 (1994) 277-285

B0895 – Variations in the chemisorption of methanol on alpha-Al2O3 in the range 200-300°C

Using a high-temperature Calvet microcalorimeter, we have studied the chemisorption process of methanol on alpha-Al2O3 at 200, 250 and 300°C. From the measurement of calorimetric isotherms, volumetric isotherms and chemisorption differential heats, we have d
P.F. Rossi, G. Oliveri and F. Guzzo, Thermochimica Acta 227 (1993) 59-66

B0884 – A microcalorimetric investigation of heteropolyacids

Differential heats of ammonia sorption onto and into heteropolyacids (HPA's) of tungsten and molybdenum (HPW, HSiW, HPMo and HSiMo) were measured microcalorimetrically to characterize the acidic properties of these metal oxygen cluster compounds (MOCC's).
L.C. Jozefowicz, H.G. Karge, E. Vasilyeva and J.B. Moffat, Microporous Materials 1 (1993) 313-322

B0881 – Microcalorimetric study of the acid-base properties of bulk and silica or y-alumina-supported vanadium oxides

The acid-base character of vanadium pentoxide, V205/SIO2 and V205/gamma-A1203 catalysts has been investigated by adsorption of ammonia and sulphur dioxide using microcalorimetry. By depositing vanadium oxide on silica, new surface sites are formed which present more acid strength than bulk vanadium pentoxide and pure silica. Alumina-supported vanadium catalysts can be regarded as acidic monolayers VOx. Sulphur dioxide was found to be selective for uncovered alumina,
J. Le Bars, A. Auroux, Journal of Thermal Analysis 40 (1993) 1277-1284

B0880 – Acidity and surface behaviour of alumina-boria catalysts studied by adsorption microcalorimetry of probe molecules

Acidity and basicity of alumina-boria catalysts supported on porous or non-porous alumina have been studied by adsorption microcalorimetry of probe molecules (ammonia, pyridine and sulphur dioxide). Despite decreasing in initial heats, the total acidity as determined by ammonia adsorption increased in number and strength as a function of percentage of boron oxide. Ammonia, as a strong base, was shown to cover all types sites from strong to weak acid sites. Pyridine, as a weaker probe, was shown to dose only the stronger sites of the samples which stay nearly constant after B2O3 coverage approaching the monolayer. The basic sites of the amphoteric alumina support are neutralized by 10 wt% of boron oxide on non-porous aJumina and 20 wt% of B2O3 on porous alumina. The catalytic activity for partial oxidation of ethane increased with acidity and reached a maximum constant value above 20 wt% of boron oxide.
G. Cucinieri Colorio, A. Auroux, B. Bonnetot, Journal of Thermal Analysis 40 (1993) 1267-1276

B0871 – Strong interactions between n-hexane and coal components during adsorption phenomena

G. Busca, P.F. Rossi and A. Vettor, JCAT (1993) 503-506

B0868 – Gas-solid interaction : heat of adsorption of 1-propanol and 2-propanol on alpha-Al2O3 between 25-200°C

P.F. Rossi, M. Bassoli, G. Oliveri, F. Guzzo, JCAT (1993) 413-416

B0865 – Adsorption microcalorimetry applied to surface energetic characterization of supported metal catalysts

J.M. Guil, A. Pérez Masia, A. Ruiz Paniego, J.M. Trejo Menayo, JCAT (1993) 173-176

B0849 – Thermodynamics of adsorbed molecules for a new acid-base topochemistry of alumina

In the present study, two methods have been applied for characterizing the surface acidity and basicity of an amphoteric y-alumlna: a titration method using Hammett indicators and a gas phase adsorption method using basic (i.e. piperidine, diethylamine, n-butylamine, ammonia, pyridine, aniline), amphoteric (Le. pyrrole, water, methylalcohol terr-butyl alcohol, acetonitrile), and acidic (i.e. m-cresol, carbon dioxide, acetic acid, sulfur dioxide) probe molecules by means of combined volumetry-calorimetry technique. The scales of acid-base strength obtained by the two methods and their reliability have been compared. Both the strength and number of acidic sites were related to the pKa of the probes. When using weaker probes (PKa I 0) only the very strong acid sites are titrated. At pKa 1 5 a plateau is reached. Moreover, in order to evaluate more precisely the gas-solid interactions, the thermodynamic behaviour of the adsorbed probes has been studied, including the isotherm, the differential heat, the integral heat and the differential molar entropies of adsorption as a function of the coverage. Integral heat corresponding to the chemisorbedvolume has been taken as a criterion to compare the acid strength of the sites. Besides, integral heat curves describe a parabola which curvature has been related to the strength of the adsorbate-adsorbent system. The values of the differential molar entropies of adsorbate confirm an immobile layer in the range 04.4 degree of coverage.
A. Gervasini, A. Auroux, Journal of Physical Chemistry 97 (1993) 2628-2639

B0837 – Calorimetric study of the acidity of alumina-boria catalysts by gaseous ammonia adsorption

Alumina-boria catalysts were prepared by impregnation of porous and non porous aluminas with various amounts of boron oxide. A calorimetric investigation of their acidity was performed by gaseous ammonia adsorption. The differential heat evolved decreases when the amount of boria on alumina increases while the corresponding number of acid sites, as determined by volumetry, increases with the amount of boron oxide. The thermal behaviour and the stability of the catalysts, when dehydration occurs, were studied by differential scanning calorimetry linked to thermogravimetry.
G.C. Colorio, A. Auroux and B. Bonnetot, Journal of Thermal Analysis 38 (1992) 2565-2573

B0836 – Calorimetric study of the acidity of alumina-boria catalysts by gaseous ammonia adsorption

Alumina-boria catalysts were prepared by impregnation of porous and non porous aluminas with various amounts of boron oxide. A calorimetric investigation of their acidity was performed by gaseous ammonia adsorption. The differential heat evolved decreases when the amount of boria on alumina increases while the corresponding number of acid sites, as determined by volumetry, increases with the amount of boron oxide. The thermal behaviour and the stability of the catalysts, when dehydration occurs, were studied by differential scanning calorimetry linked to thermogravimetry.
G.C. Colorio, A. Auroux and B. Bonnetot, Journal of Thermal Analysis 38 (1992) 2565-2574

B0829 – Caractérisation de l’intéraction bitume-agrégat par microcalorimétrie isotherme

L'enthalpie d'interaction entre bitume et agrégat a été mesurée par microcalorimétrie isotherme à 160°C. Ce phénomène d'association est exothermique et dévelope des énergies de liaisons de l'ordre de quelques joules par gramme d'agrégat. Ces enthalpies d'interaction dépendent principalement de la surface spécifique du granulat et de l'origine ou de la nature physico-chimique du bitume. En outre, des relation semblent exister entre l'énergie de liaison et la teneur en asphaltènes du bitume. Une assez bonne corrélation a été trouvée également entre l'enthalpie mesurée et les résultats du test empirique d'évaluation de l'adhésivité passive selon la méthode Laboratoire Central des Ponts et Chaussées (LCPC). De manière plus inattendue, la composition chimique des agrégats ne semble jouer qu'un rôle mineur dans ces énergies de liaisons.
J.M. Létoffé, P. Claudy, J.P. Planche and L. Germanaud, Thermochimica Acta 210 (1992) 27-40

B0824 – Calorimetric study of the reaction between formic acid and N,N,N’,N’, tetramethylethylenediamine from the aspect of thermal energy storage

The attack by formic acid on the nitrogen electron pairs of N,N,N',N'-tetramethylethylenediamine leads to the stoiehiometric salt or to many other complexes with different molar fractions. Physical and thermodynamic parameters of two adducts, obtained by calorimetric study, are discussed in terms of their use as potential phase change materials in thermal energy storage because of their large heat of fusion between 288 and 333 K.
M. Salman, Y. Girault, N. Balbi and L. Elegant, Journal of Thermal Analysis 37 (1991) 2389-2394

B0777 – Calorimetric investigations of adsorption of quaternary alkylammonium bromides from aqueous solutions on a hydrophilic silica surface

M. Bouzerda, J. Zajac, J.L. Trompette, S. Partyka, JCAT (1992) 249-256

B0773 – Etude microcalorimétrique du mécanisme d’adsorption d’acides polyacryliques et de polyacrylamides sur le dioxyde de titane : Effet du pH et de la nature des ions

Y. El Attar Sofi, A. Foissy, JCAT (1992) 331-334

B0771 – Energies et mécanismes d’insertion et de désinsertion de l’anhydride sulfurique gazeux ou liquide dans le graphite suivis par analyse thermique et calorimétrique

P. Vast, JCAT (1992) 335-342

B0767 – Relationship between molecular interaction parameters and enthalpies of transfer of a Lewis acid from vapor to a set of Lewis bases

Ho Nam-Tran, Nguyen Van Phat, F. Sabra, P. Ruelle, M. Buchmann, U.W. Kesselring, Université de Lausanne (1992)

B0766 – Calorimetria diferencial de barrido (DSC) y microcalorimetria isoterma aplicadas a la caracterizacion de catalizadores

J.M. Guil Pinto,

B0749 – Microcalorimetric investigation of the acidity and basicity of metal oxides

The acidity and basicity of about twenty simple oxides mainly used in catalysis and ceramic materials were investigated by adsorption microealorimetry of basic and acidic gas probe molecules such as ammonia and carbon dioxide. The determination of the number, strength and site energy distribution of both acidic and basic sites in all the samples led to an improved description of the surfaces. The results allowed us to classify our samples in three main groups in relation to their acidic, basic or amphoteric character. Their acid-base behaviour was tentatively correlated to more general electronic and redox data given in the literature such as the electronegativity.
A. Gervasini and A. Auroux, Journal of Thermal Analysis 37 (1991) 1737-1744

B0738 – Etude par microcalorimétrie de la réactivité de deux ammoniacates de chlorure de manganèse

The reaction [Mn(NH3)2]C12 + 4NH3 ~ [Mn(NH3)6]C12, which is of potential use in chemical heat pumps, was studied by means of differential scanning calorimetry. The thermodynamic conditions, the enthalpy of the reaction, and the heat capacity values for MnCI2, [Mn(NH3)z]CI2 and [Mn(NH3)6]CI2 were measured. The influence of the reaction kinetics of the experimental procedure and some parameters such as sample temperature, ammonia pressure and scanning rate was examined.
A. Marty, Journal of Thermal Analysis 37 (1991) 479-498

B0712 – The use of thermoporometry for the determination of the pore size distribution of Raney nickel catalysts and ion exchange catalysts.

M-J. Luys, P.H. van Oeffelt, DSM - GELEEN

B0700 – Calorimetric study of NH3 and CO2 adsorption on erionites and zeolites L.

The heats of adsorption of CO2 and NH3 on sodium-potassium, calcium-potassium and hydrogen erionites and on zeolites L containing Na+, K+, Ca2+, Mg2+ and La3+ ions were calorimetrically measured. At low coverages a considerably smaller number of Ca2+ ions in erionites is involved in the interaction with CO2 molecules compared with NH3 molecules. The substitution of Na+ ions by Ca2+, Mg2+ or La3+ in zeolites L leads to a decrease in heats of adsorption of CO2. The number of Mg2+ ions forming adsorption complexes with NH3 in zeolites L significantly exceeds the corresponding numbers of Ca2+ and La3+ ions. The ion exchange data suggest that a greater number of Mg2+ ions in contrast to Ca2+ and La3+ ions occupy the main channel sites.
S.S. Khvoshchev and A.V. Zverev, Thermochimica Acta 164 (1990) 315-322

B0694 – Microcalorimetric study of the acidity and basicity of metal oxide surfaces

The adsorption of probe molecules such as NH3 and C02 was studied on about 20 simple metallic oxides by use of microcalorimetry in order to determine the number and character of basic and acidic surface sites. Microcalorimetry allowed a simultaneous determination of the strength and energy distribution of the adsorption sites. The adsorption isotherms, the differential heats, the integral heats, and the energetic histograms are given for NH3 and C02 adsorptions. Relationships between the average adsorption heats of NH3 and C02 have been found as a function of the ionic character percentage and of the charge/radius ratio.
A. Auroux and A. Gervasini, The Journal of Physical Chemistry 94 (1990) 6371-6379

B0657 – Etude microcalorimétrique de l’acidité et des capacités calorifiques des heteropolyanions tungstiques

A. Auroux, F.X. Cai, F. Lefebvre, AFCAT (1990) 103-111

B0654 – Characterisation of heterogeneous catalysts by modified flow microcalorimetry.

A modified batch gas sampling-carrier gas flow (BGS-CGF) microcalorimetric method is described and discussed. The values of the heats of differential adsorption of ammonia on ZSM-5 measured by this method agree well with those obtained from other calorimetric techniques. The differential and integral heats of adsorption of ammonia on SiO2-Al2O3, on zeolites and on some commercial catalysts were determined. The calorimetric measurements of ammonia adsorption were used to characterise the acidity of those samples. The acidity of the samples measured by the calorimetric method were correlated with their activities evaluated on a pulse reactor.
Z. Dichang, D. Chongjing, H. Mingyuan, M. Enze, Z. Zhongliang, Thermochimica Acta 165 (1990) 171-182

B0652 – The use of a heat-flow differential scanning calorimeter as a plug-flow fixed-bed reactor in heterogeneous catalysis

Some aspects of the use of a heat-flow differential scanning calorimeter for studying catalysts are described in this study. The DSC is coupled to a mass spectrometer in order to analyse the gas mixture that leaves the catalyst bed in the DSC reactor. DSC is a physical means of analysis: it does not disturb the reaction. Attention is focused on the calibration of the DSC with a probe on the basis of the so-called Joule effect. The calibration is carried out over a large temperature range of 300-700 K both in the absence of flow and under flow conditions.
J.J.P.Biermann, P.P.Coelen, H. den Daas, F.J.J.G. Janssen, Thermochimica Acta 144 (1989) 329-337

B0642 – Low temperature isotopic exchange of molecular oxygen via the reaction of NO, NH3, and O2 over supported vanadia and molybdena catalysts

This study describes the behaviour of NO, NH3 and18O2 over supported molybdena and vanadia catalysts. The study was carried out using differential scanning calorimetry. The catalysts show different behaviour with respect to the reaction of NO, NH3 and O2 and similar behaviour with respect to the formation of water.
J.J. Biermann and F.J. Janssen, Catalysis Letters 2 (1989) 385-394

B0641 – The use of DSC to study the selective calalytic reduction of NO with NHs

Differential scanning calorlmetry (DSC) has the advantage that it allows the chemical reaction rate to be followed at temperature-programmed conditions. In complicated reactions, such as the reaction of NO and NH3 over a catalyst, it is unwise to employ the heat of the overall reaction as a measure of the extent of the reduction of NO. Therefore, these measurements are accompanied by mass spectrometric analysis in order to measure the activity and selectivity of the reaction. This paper presents the results of the effect the heating rate has on the performance of a selective V2O5 on TiO2/SiO2 catalyst. Moreover, typical results of the reaction of NO, NH3 and O2 over samples of a non-selective catalyst (CuO on SiO2) and a selective catalyst (V2O5 on TiO2/SiO2) are presented.
J.J.P.Biermann, H. den Daas, F.J.J.G. Janssen, Thermochimica Acta 133 (1988) 169-174

B0638 – The application of thermoanalytical methods for the characterization of zeolite catalysts

Through the coupling of a DSC 1 ! 1 (Setaram) with a gas dosing valve and a catharometer detector, equipment was developed for the investigation of adsorbents and catalysts. This equipment was applied for the determination of differential and integral heats of adsorption of C2 to C4 hydrocarbons on zeolites of the pentasile family. The proposed method has sufficient accuracy for the determination of adsorption heats for technical products. The advantages and the problems of the presented method are discussed.
H. Siegel and H. Splinder, Journal of Thermal Analysis 33 (1988) 903-908

B0620 – Microcalorimetric study of the interaction of CO, O2 and CO + O2 with Pt/SnO2 and SnO2 catalysts

The heat evolved in the interaction of CO, O2, and CO + O2 with SnO2 and Pt/SnO2 catalysts was evaluated at different temperatures in the range 300-475 K using microcalorimetry. The effect of oxygen and hydrogen pretreatments of the samples on the heat evolved shows that in the case of Pt/SnO2, the values were higher for the oxidized sample as compared to the reduced sample, whereas the trend was reversed for metal-free SnO2. The thermochemical data reveal heterogeneity of CO or O2 adsorption/reaction sites and show that the heat evolved in interaction of a gas is considerably influenced by the chemical nature of the catalyst surface and by the presence of preadsorbed species. The data support the view that the lattice oxygen abstraction from SnO2 plays an important role in CO oxidation at all the catalyst temperatures under study. The presence of platinum is found to augment Sn4+ => Sn2+ conversion. It is suggested that the energy released in the chemisorption of carbon monoxide or oxygen over Pt gives rise to a localized temperature surge in the vicinity of metal sites and this additional source of energy leads to enhanced CO oxidation activity of Pt/SnO2 via accelerated lattice oxygen abstraction.
N.D. Gangal, N. M. Gupta and R.M. Iyer, Journal of Catalysis 126 (1990) 13-25

B0619 – Calorimetric determination of the superficial acidity and active sites in Ziegler-Natta catalysts

The surface acidity and active sites of Ziegler-Natta catalysts (TiCl3, 1/3AlCl3-MgCl2) before and after allevlation have been characterized by measuring the differential heats of adsorption of various probe molecules in the vapour phase. The surface acidity was measured by the adsorption of acetonitrile. This probe molecule appeared to be adsorbed by all metallic sites on the surface, and the order in energetic distribution of these sites showed three populations of sites of decreasing strength which have been proposed as Al> Ti> Mg. Characterization of the sites active in polymerization was done using various olefins with different steric hindrance but all inactive towards polymerization such as isobutene, trans-2-hexene and cyclohexene.
A. Auroux, K. Bujadoux, J.C. Jannel and D. Lalart, Reactivity of Solids 7 (1989) 67-74

B0618 – Calorimetric study of the acidity of Y-zeolites treated with silicon tetrachloride

The acidity of synthetic HY samples dealuminated with silicon tetrachloride vapour at various temperatures is investigated using microcalorimetry. The work covers sample preparation, characterization, and acidic properties. The differential heats of ammonia adsorption versus coverage and the acidity spectra are described. The catalytic performance is measured in the hydrogen transfer reaction.
Z.C. Shi, A. Auroux and Y. Ben Taarit, Canadian Journal of Chemistry 66 (1988) 1013-1017

B0616 – Calorimetric investigation of the acidity of dealuminated Y-type zeolites using various basic probes

A. Auroux, Z.C. Shi, N. Echoufi, Y. Ben Taarit, Studies in Surface Sciences and Catalysis 46, Zeolites as catalysts, sorbents and detergent builders, Apllications and Innovations (1988) 377-387

B0615 – Mechanisms of metal ion adsorption on activated alumina.

J.W. Novak Jr., R.R. Burr, R. Bednarik, Metals Speciation, Separation and Recovery (1987) 475-492

B0613 – Adsorption calorimetry in surface chemistry

The measurement of the energy of interaction of a molecule with a surface as a function of coverage provides information on the state of the surface and on the thermodynamic characteristics of the adsorption process. Access to ?ads H is usually obtained on polycrystalline materials by means of a microcalorimeter connected to a dosing device which enables the simultaneous measurement of small uptakes and related heats. Small increments in the adsorba te from the lowest coverage to saturation can thus be evaluated. Successive adsorption-desorption cycles allow the separation of effects due to reversible and irreversible phenomena. The adsorption of the same adsorptive onto variously pretreated solids or on materials of different origin yield evidence of differences in the state of the surface. The application of this technique in various fields of surface science will be reported and the usefulness of joint use of microcalorimetry with other techniques will be stressed.
B. Fubini, Thermochimica Acta 135 (1988) 19-29

B0612 – A microcalorimetric method for the measurement of enthalpies of solution of gases in liquids.

An experimental set-up for measuring enthalpies of solution of gases in liquids is described. This apparatus consists of a vacuum line for gas handling and a Tian-Calvet microcalorimeter. The gas quantities are measured by a mercury manometer. The gas is injected into the calorimeter cell through a sintered glass-mercury one-way valve. The various sources of systematic and random errors are analyzed. The experimental method allows the measurement of the reaction stoichiometry and the distinction between fast and slow reactions; on the calorimeter time-constant scale. Along with spectroscopic studies of the reaction products, these features enable a more thorough characterization of the final state than the usual calorimetric techniques used for similar studies. A summary of the applications in the fields of physical organic chemistry, polymer chemistry and natural gas refining is given.
P-C. Maria, J-F. Gal, L. Elegant and M. Azzaro, Thermochimica Acta 115 (1987) 67-81

B0610 – Contribution of microcalorimetry to the study of adsorption mechanisms of ionic and non-ionic molecules at the solid-water interface

Adsorption of an ionic surfactant (Octyl Benzene Sulfonate: OBS), sodium salicylate, and a nonionic surfactant (octylphenyl polyoxyethylene: TX 100) onto hydrophilic (silica and alumina) and hydrophobic (activated carbon) surfaces was studied by batch adsorption microcalorimetry combined with the adsorption isotherms. Comparison between the corresponding enthalpic curves showed: 1. the micellar structure of TX 100 adsorbed on the silica, 2. the liquid crystal state of OBS adsorbed on alumina, 3. the interactions of the alkyl chain of the surfactants and the benzene ring common to the three adsorbates with the activated carbon surface.
F. Thomas, J.Y. Bottero, S. Partyka and D. Cot, Thermochimica Acta 122 (1987) 197-207

B0606 – Construction and testing of a gas-solid reaction calorimetry system using a Tian-Calvet microcalorimeter

A gas-solid calorimetry system has been constructed, in which a Tian-Calvet micro-calorimeter (low temperature model) and a gas-manipulation facility are incorporated. This system was tested for the reaction NiCl3(cr) + 6NH3(g) = [Ni(NH2)6Cl2(cr) at 351 and 362 K. The derived enthalpy changes were reduced to the value at 298.15 K, which agreed with the value based on the literature data of standard enthalpies of formation of the species that participate in the above reaction.
N. Kuriyama and M. Sakiyama, Thermochimica Acta 132 (1988) 75-87

B0588 – DSC-GC studies on the oxidation of CO over vanadia catalysts

The oxidation of CO on unsupported, supported and Pd-doped vanadia catalysts has been studied in a coulpled DSC-GC system. By the simultaneous determination of the conversion and the molar heat of CO2 formation, calorimetric information revealing the partial reduction of the surface before the attainment of a steady state have been obtained.
Zs. Roder, G. Mink and I. Bertoti, Thermochimica Acta 107 (1986) 181-187

B0576 – Comparative calorimetric studies of the acidity of zeolites by static and temperature-programmed methods of ammonia adsorption and desorption

A combined TG-DSC 111 apparatus from Setaram has been used for the characterization of HZSM5, H-Y and H-Ferrierite zeolites. Starting from the NH4 forms it was possible to determine the weight loss under vacuum at increasing temperature up to 863 K, the subsequent weight gain upon ammonia adsorption at room temperature and finally the weight loss at increasing temperature. The heats of ammonia adsorption and desorption during the same experiments could also be determined. The experimental results indicate clearly a great heterogeneity in acid strengths. These results are compared to those obtained by a static method using a classical gas-handling line linked to a heat-flow microcalorimeter.
A. Auroux, Y.S. Jin, J.C. Vedrine, L. Benoist, Applied Catalysis 36 (1988) 323-330

B0570 – Microcalorimetric studies of the acidity of the small-pore zeolite H-RHO

Microcalorimetry and infrared studies of ammonia adsorption are used to investigate the acidic properties of the small-pore zeolite H-RHO. Shallow-bed calcination of NH4-RHO at 400°C produces a nearly pure H-RHO with framework hydroxyl Brönsted acid sites having a heat of adsorption of ammonia of 170 kJ mol-1. Shallow-bed calcination at 600° or 700°C destroys 25% and 50% of the framework hydroxyls, respectively, producing 'super acid' sites and a new type of hydroxyl characterized by an infrared hydroxyl band at 3640 cm-1. This new hydroxyl site is only weakly acidic; evidence suggests it may have a heat of adsorption of ammonia of 60 kJ mol-1. Shallow-bed calcination also produces a small number of strongly acidic Lewis sites. The high acidity of these strong Lewis sites raises the average energy of ammonia adsorption by up to 15 kJ mol-1 for H-RHO calcined at 600° or 700°C. Immobile adsorption of ammonia and preferential location of the most energetic sites in the internal pores of the zeolite structure results in a 'bell-shaped' curve for the initial heat of adsorption for H-RHO calcined at 600°C.
R.D. Shannon, R.H. Staley and A. Auroux, Zeolites 7 (1987) 301-306

B0569 – Properties of boron-substituted ZSM-5 and ZSM-11 zeolites

Using NMR and IR spectroscopy boron-substituted pentasil zeolites are found to contain four-coordinated B in the hydrated state and three-coordinated B in the dehydrated state. In addition a new tetrahedral B site assigned to (HO)2B(H2O)(OSi) was characterized by its NMR quadrupole coupling constant and asymmetry parameter. Ammonia adsorption microcalorimetry gave heats of adsorption of ~65 kJ/mol for H---B---ZSM-11 and showed that B-substituted pentasils have only very weak acidity. Calcination at 800°C increased the heat of NH3 adsorption to ~170 kJ/mol by creation of strong Lewis acid sites. The lack of strong Bronsted acid sites in H---B---ZSM-11 was confirmed by poor catalytic activity in methanol conversion and in toluene alkylation With methanol.
G. Coudurier, A. Auroux, J.C. Vedrine, R.D. Farlee, L. Abrams and R.D. Shannon, Journal of Catalysis 108 (1987) 1-14

B0568 – A microcalorimetric study of NH3-sorption onto differently modified and pretreated ZSM-5 surfaces

A comparative study of NH3-sorption onto several ZSM-5 samples differently modified by acid-dealumination, boron incorporation in the zeolite (by synthesis), as for lattice aluminum and boron impregnation as H3BO3, has been carried out at 423 K for differently pretreated (1.33 mPa/673 K/12 h and 1.33 mPa/1073 K/12 h) surfaces. Various volumetric, calorimetric and thermokinetic parameters have been found to correlate well, revealing that (i) acid treatment, whilst it eliminates a portion of the zeolite aluminum of potential acidity, creates new surface Bronsted sites of moderate acidity, (ii) boron replacement for a portion of the zeolite aluminum, however, does not alter the number of exchangeable acid sites, decreases markedly the overall zeolite acidity and enhances heterogeneous distribution of surface acidity, and (iii) boron impregnation, though it neutralizes proportionally the zeolite Bronsted acidity for samples pretreated at 673 K, appears to neutralize the zeolite Lewis acidity as well for samples pretreated at 1073 K, which results in a drastic loss of the overall zeolite acidity. The mechanistic implications illustrating the effect of such modifications are described.
M.B. Sayed, Thermochimica Acta 126 (1988) 325-337

B0561 – New probes for an accurate calorimetric determination of the acidity of zeolites

A. Auroux, Innovation in Zeolite Material Science, 385-391

B0559 – Acidic ferrierite type zeolite – II Steamed and acid leached treatment

Ferrierite type zeolite was thermally treated under steam at temperatures ranging from 870 to 970 K followed by acid leaching with hydrochloric acid solution at 360 K. It was observed that framework aluminium was extracted from the lattice but remained within the pores and channels. A decrease in the number but not the strength of acidic sites followed with a subsequent decrease of catalytic activity and of lifetime on stream. The changes in sorptive properties (diffusivity, capacity) were rather minor for n-hexane and 3-methylpentane adsorbates but very important for toluene. The steamed materials appeared to present no additional interest as acid type catalysts but to be more selective for aromatics diffusion, i.e. as separating columns or adsorbants.
Y.S. Jin, A. Auroux and J.C. Vedrine, Applied Catalysis 37 (1988) 21-33

B0558 – Acidic ferrierite type zeolite – I Physicochemical and catalytic properties

Ferrierite samples with two aluminium contents (silicon:aluminium = 15.4 and 7.8) were synthesized and acidified through NH+4 exchange. One sample was pure ferrierite whereas the second was a mixed ferrierite+mordenite phase. Because of its small pore channel structure the ferrierite exhibits striking shape selectivity properties for n-hexane cracking and methanol conversion reactions. Acidic properties, as evidenced by infrared and microcalorimetry techniques, of ammonia adsorption correspond to strong acidity. The intimate presence of mordenite in one sample results in severe limitation of the adsorption and diffusion properties and subsequently to higher shape selectivity and also to fast deactivation versus time-on-stream. This is interpreted in terms of intergrowths of ferrierite and mordenite phases.
Y.S. Jin, A. Auroux and J.C. Vedrine, Applied Catalysis 37 (1988) 1-19

B0557 – Calorimetric investigation of the effect of dealumination on the acidity of zeolites

Calorimetric investigation of NH3 adsorbed on a variety of dealuminated Y and mordenite zeolites showed a drastic change of the initial values and coverage dependance of differential heats of adsorption. These changes were interpreted in terms of the presence within the zeolite porous matrix of an alumina type phase which is behaving as an additional acidic component.
A. Auroux and Y. Ben Taarit, Thermochimica Acta 122 (1987) 63-70

B0549 – Thermal analytical investigations on (AgNa)-A zeolites

During the thermal treatment of silver-exchanged forms of zeolite A, five desorption effects are observed which are assigned to different adsorption forms of water. Dehydration (of water) is accompanied by autoreduction of some of the silver ions. The water adsorption capacity of the (AgNa)-A zeolites depends upon the degree of autoreduction and reduction in hydrogen, respectively. It is possible to suppress the autoreduction by heating in oxygen. With increasing content of silver ions the thermal stability of the samples is decreased. The same was observed after successive reduction in hydrogen.
B. Wolf, H. Siegel, R. Schollner and A. Dyer, Thermochimica Acta 87 (1985) 117-127

B0547 – Adsorption at the liquid/solid interface : the part of microcalorimetry in the fields of enhanced oil recovery, lubrication and water purification

After listing the problems of adsorption which are more specifically related to each of these three fields, typical results obtained by liquid/solid adsorption microcalorimetry are reported and commented on. Batch adsorption microcalorimetry is shown to be especially interesting as a sensitive detector to follow the kinetics of adsorption whereas liquid-flow adsorption microcalorimetry -although less universal- is a more convenient tool for a preliminary screening of the systems and also to study desorption.
J. Rouquerol, Thermochimica Acta 95 (1985) 337-350

B0538 – The adsorption of methane on H-ZSM-5 zeolite

The adsorption of CH4 on H-ZSM-5 zeolite has been investigated by microbalance technique, ir-spectroscopy and calorimetry. CH4 is reversibly adsorbed in the temperature range investigated (225 to 723 K). The adsorption can be described by Langmuir isotherms with a heat of adsorption of about 28 kJ/mole. CH4 shows 3 vibrations in the adsorbed state, the induced v1 vibration at 2900 cm-1, the v3 vibration at 3005 cm-1 and the induced 2v2 vibration at 3060 cm-1. The OH-vibration of the Brönsted sites is shifted to lower frequency by the adsorption of CH4
H. Papp, W. Hinsen, N.T. Do and M. Baerns, Thermochimica Acta 82 (1984) 137-148

B0501 – Effect of impregnation of ZSM-5 with H3BO3 on its acidity: A microcalorimetric study of NH3 adsorption

A computer-programmed microcalorimetric investigation of NH3 adsorption at 423 K was applied to characterize the modified acidity of ZSM-5 zeolite impregnated with increasing amounts of H3BO3. Zeolite samples were pre-treated at two different temperature regimes: 1.33 mPa/673 K/12 h and 1.33 mPa/1073 K/12 h. A combination of volumetric, calorimetric and thermokinetic data revealed that the former pretreatment was responsible for removing part of the Brnsted sites, while the latter also induced pore plugging, which therefore drastically reduced the overall zeolite acidity. Zeolite impregnation with increasing amounts of H3BO3 contributed to an increased loss of acidity. Special emphasis is placed on the effect of high-temperature treatment on lattice element exchange and its importance for zeolite-binder interactions.
M.B. Sayed, A. Auroux and J.C. Vedrine, Applied Catalysis 23 (1986) 49-61

B0500 – The effect of dealumination on the structure and acidic properties of offretite

C. Fernandez, A. Auroux, J.C. Vedrine, 7th Int. Zeolite conf, Tokyo, (1986) 345-350

B0499 – The characterisation of surface acidity

P.N. Aukett, BP Research Centre (UK)

B0497 – Acid strength of silica-supported oxide catalysts studied by microcalorimetric measurements of pyridine adsorption

N. Cardona-Martinez, G. Connell, J.A. Dumesic, AICHE Meeting, Miami Beach (USA) (1986)

B0495 – Etude calorimétrique de l’effet de la désalumimnation sur l’acidité des zéolithes

A. Auroux, Y. Ben Taârit, AICAT, Ferrara, (1986) 88-91

B0493 – Modified zeolite acidity as key to interpreting modified catalytic reactivity. A microcalorimetric study of NH3 sorption over boron-impregnated ZSM-5

The small, but strong base NH3 has been applied to probe modified acidity of the small pore zeolite, ZSM-5, impregnated with boric acid in a microcalorimetric study. A combination of computer processed volumetric, calorimetric, and thermokinetic data allows to briefly describe the sorption process and identify modified zeolite acidity. The data have shown consistently that while zeolite sorption capacity towards NH3 is slightly modified, the overall acidity is considerably reduced with increased content of the boron modifier.
A. Auroux, M.B. Sayed and J.C. Védrine, Thermochimica Acta 93 (1985) 557-560

B0488 – Microcalorimetric studies of the adsorption of alcohols on metal oxide surfaces

P.F. Rossi, G. Busca, G. Ramis, V. Lorenzelli, AICAT, Ferrara, (1986) 369-372

B0487 – Etude par microcalorimétrie de l’adsorption d’hydrogène sur sulfures des métaux de transition

R. Melis, N. Boutarfa, M. Gravelle-Rumeau-Maillot, M. Lacroix, M. Vrinat, M. Breysse, P.C. Gravelle, AICAT, Ferrara, (1986) 104-109

B0486 – Thermodynamic and spectroscopic characterization of CO adsorption on oxides. Titanium dioxides

V. Bolis, B. Fubini, AICAT, Ferrara, (1986) 100-103

B0470 – Shape selectivity and acidity of ZSM-5 and ZSM-11 type zeolites

J.C. Vedrine, A. Auroux, G. Coudurier, P. Engelhard, J.P. Gallez, G. Szabo, 6th Int Zeolite Conf., Guildford (U.K.) (1984) 497-505

B0469 – Microcalorimetric characterization of acidity and basicity of various metallic oxides

A .Auroux, J.C. Vedrine, Catalysis by Acids and Bases (1985) 311-318

B0468 – Combined physical techniques in the characterization of zeolite ZSM-5 and ZSM-11 acidity and basicity

Résultats de l'étude par spectrométrie IR et RPE et par microcolorimétrie des propriétés acido-basiques des zéolites acide ZSM-5 et ZSM-11. Détermination, aussi, par microscopie électronique et par spectrométrie photoélectronique avec excitation par rayons X des dimensions et formes des particules de zéolite et la distribution d'Al dans les particules. Estimation, enfin, des propriétés catalytiques pour la conversion du méthanol
J.C. Vedrine, A. Auroux, G. Coudurier, A.C.S. symposium series 248 (1984) 253-273

B0466 – Catalytic properties of H-mordenite modified with fluorine

Etude par adsorption de NH[3]; cracking du cumène
K.A. Becker, S. Kowalak, Journal of the Chemical Society. Faraday Transactions 81 (1985) 1161-1166

B0465 – Fluorine modification of zeolite catalysts

K.E. Becker, K. Fabianska, S. Kowalak

B0449 – Identification of surface sites on potentially catalytic solids by adsorption calorimetry

V. Bolis, G. Della Gatta, B. Fubini, E. Giamello, L. Stradella, G. Venturello, Gazetta chimica Italiana 112 (1982) 83-89

B0440 – Utilisation du DSC 111 en catalyse (différents articles russes)

Congrès russe du DSC 111, (1983)

B0439 – Utilisation de la calorimetrie en catalyse (différents articles russes)

Congrès russe catalyse, (1983)

B0438 – Microcalorimetric characterization of acidity and basicity of various metallic oxides

A. Auroux, J. Vedrine, Coll. Int. CNRS, Villeurbanne (1984) 117-119

B0437 – Calorimetric study of adsortion of ammonia at 420K on bismuth-molybdate (2:1)

L. Stradella, Coll. Int. CNRS, Villeurbanne, (1984) 83-85

B0436 – Structure and acidic properties of high silica faujasites

F. Mauge, A. Auroux, P. Gallezot, J.C. Courcelle, Ph. Engelhard, J. Grosmangin, Coll. Int. CNRS, Villeurbanne, (1984) 44-52

B0418 – Estudo de alumina de transiçao por microcalorimetria mudança do calor de adsorçao de amonia

A. Auroux, C.M Sachette, Seminaire Catalyse, Sao Paulo (1983)

B0414 – Chemical, physical and catalytic properties of ZSM-5 and ZSM-11 zeolites : a study by electron microscopy, EDX-STEM and XPS

In order to ascertain the relative importance of shape-selectivity due to channel size limitations and of zeolitic grain size in the conversion of methanol to higher hydrocarbons on Pentasil-type zeolites, several catalysts were prepared using different synthesis and acidification procedures. Acidity of the samples was determined by microcalorimetry of the differential heat of NH3 adsorption. Crystallite size and morphology were determined by high resolution electron microscopy while the Al distribution across the crystallites was monitored by high resolution EDX-STEM and XPS. The ZSM-11 samples were composed of spherical aggregates having diameter of 0.6 ± 0.2 µm for one batch and 6 ± 2 ?m for another batch. The former sample was composed of aggregates of crystals of 5 to 10 nm in diameter and gave an XRD pattern with broad peaks. However, infrared vibrational spectra and microdiffraction were consistent with ZSM-5 or -11 material. The latter sample was composed of aggregate cores with crystalline needles of 200 to 400 nm in size emerging from the surface. EDX-STEM technique shows that within aggregate crystals the Al distribution is rather homogeneous while a great heterogeneity exists between grains. XPS data show that the outermost layers are in average richer in Al than the inner layers. In the sample with needles the AI content within the needles is homogeneous but varies from one grain to another one. However this Al content is 1.5 to 4 times lower than in aggregate core of each grain. XPS technique also shows that the outer layers of the needles are very poor in Al (Si:Al = 70 ± 10). ZSM-5 samples were shown to be composed of parallelipipeds about 0.5 to 1 ?m in size with a narrow size distribution. The Al content was shown to be approximately homogeneous within the grain but very different from one grain to another (factor 2 to 3). Acidification by HCl was also shown by XPS to eliminate lattice Al from the outerlayers. It appears from the selectivities in aromatic hydrocarbons in the reaction of methanol conversion to a mixture of hydrocarbons that H-ZSM-5 yields preferentially A8 aromatics whereas H-ZSM-11 gives more A9 aromatics. This holds true for both acidification procedures and for different crystallite sizes. This was attributed to different physical constraints resulting from the difference in the free void space at the channel intersections between ZSM-5 and ZSM-11 zeolites. Large crystallites of ZSM-11 (second sample) gave more light aliphatics (C1 + C2) and less C6+ aliphatics and A9+ aromatics than the small crystallites (first sample) and resemble the ZSM-5 zeolite of about the same crystallite size for this particular aspect. The acid strength of active sites, as characterized by microcalorimetry of NH3 adsorption, and the acid site distribution were observed not to play an important role in methanol conversion reaction, as long as sufficient acid sites are present. Particular emphasis is placed upon misleading conclusions on the particle size effect which may stem from inaccurate SEM characterization and on the oversimplification of steric limitations due to the size of the channels.
A. Auroux, H. Dexpert, C. Leclercq and J. Vedrine, Applied Catalysis 6 (1983) 95-119

B0413 – Catalytic and physical properties of phosphorus modified ZSM-5 zeolite

H-ZSM-5 zeolite modified by phosphorus (1.1 and 2.0 wt%) was studied by means of infrared spectroscopy and microcalorimetry for acidity characterization, by ESCA for determining elementary composition in the outer layers (depth - 50 Å) with respect to the bulk (? - several ?m), and lastly by catalytic reaction analysis of methanol conversion. It was found that phosphorus neutralizes acidic sites primarily at the entrance of the channels of the zeolite particles in the same manner as do carbonaceous residues after some time of reaction. However, the strongest acid sites remain unmodified, which leads to the suggestion that the aluminium distribution and subsequently the acid site strength distribution along the zeolite channels is heterogeneous. Phosphorus-modified zeolites gave a higher yield of light olefins (C2=---C4=) and subsequently a smaller yield of saturated aliphatics and aromatics than the parent zeolite in the methanol conversion reaction. The phosphorus-modified zeolite gave similar yields of the meta + para isomers of xylene and of ethyltoluene and a smaller yield of the ortho isomers. Lastly the yield of heavier aromatics A9+ was greatly decreased by the addition of phosphorus. The changes in selectivity were tentatively assigned to slight modifications in channel size and to increased tortuosity due to phosphorus compounds bonding to the zeolite framework, rather than to changes in acid strength.
J.C. Védrine, A. Auroux, P. Dejaifve, V. Ducarme, H. Hoser and S. Zhou, Journal of Catalysis 73 (1982) 147-160

B0406 – Calorimetric study of the absorption of n-butane and but-l-ene on a highly dealuminated Y-type zeolite and on silicalite

Differential heats of adsorption have been determined calorimetrically for n-butane and but-l-ene on molecular sieves US-Ex and silicalite. It is shown that on US-Ex, but-l-ene isomerizes whereas on silicalite it is physically adsorbed. The heat of adsorption for but-l-ene on silicalite was found to be less than the heat of adsorption for n-butane.
H. Thamm, H. Stach and W. Fiebig, Zeolites 3 (1983) 95-97

B0403 – Absorption de l’acide cyanhydrique sur les sites acides de lewis de la silice

J.C. Petit et al., AFCAT, La Gaillarde (1983) 267

B0395 – Etude calorimétrique de l’absorption d’hydrogène sur des catalyseurs d’hydrodésulfuration.

P.C. Gravelle et al., AFCAT, La Gaillarde (1983) 84

B0386 – Characterisation of heterogeneous catalysts by thermochemical reactions

H.L. Krauss, R. Hopfl, Proceedings and Esta, Aberdeen (1981) 175

B0359 – Etude microcalorimétrique des propriétés superficielles du quartz et de la silice non poreuse action fibrogène

V. Bolis et al., AFCAT, Genève (1982)

B0351 – Microcalorimetric study of the acidity of H-ZSM 5 zeolite.

A. Auroux et al., 5th Int. Confer. on Zeolites (1980)

B0345 – Characterization of small pore zeolithes by adsorption of ammonia.

P.C. Gravelle et al., Int. CNRS, Aix-en-Provence (1981)

B0326 – Supported iron catalysis : particle size dependence of catalytic and chemisorptive properties.

H. Topsoe, 7th Int. Congress of Catalysis, Tokyo (1980)

A2365 – Activity and stability enhancement of Ni-MCM-41 catalysts by Rh incorporation for hydrogen from dry reforming of methane

Ni incorporated and Ni–Rh incorporated bimetallic MCM-41 like mesoporous catalysts, which were synthesized following a one-pot hydrothermal procedure, showed very high activity in dry reforming of methane. Among the Ni incorporated catalysts, Ni-MCM-41-V, with a Ni/Si ratio of 0.19, showed the best catalytic performance. Rh incorporation into this catalyst by the one-pot procedure improved both activity and time on stream stability of the catalyst. However, Rh incorporation by impregnation caused instabilities due to coke formation, after about 11 h of reaction time. Occurrence of reverse water gas shift reaction caused higher CO selectivity than H2 selectivity, with the Ni incorporated catalysts. Rh incorporation into these catalysts decreased the relative significance of reverse water gas shift reaction, with respect to dry reforming reaction
Huseyin Arbag, Sena Yasyerli, Nail Yasyerli, Gulsen Dogu, International Journal of Hydrogen Energy 3 5 ( 2 0 1 0 ) 2 2 9 6 – 2 3 0 4

A2364 – Chemical transformations of sulfur compounds adsorbed onto activated carbon materials during thermal desorption

Four commercial activated carbon materials, including two fiber cloths, were studied as adsorbents for three organosulfurs in terms of adsorption and thermal regeneration, the organosulfurs being ethyl mercaptan, isopropyl mercaptan and tetrahydrothiophene. Their performance is interpreted using their inherent porosity and surface functional groups characteristics. The most porous granular carbon with acidic surface functional groups performed better than the other adsorbents at a high organosulfur concentration. However, at a low concentration the fiber cloths exhibit greater adsorption than granular materials, thereby confirming their potential to desulfurize various gases. Thermal desorption was performed in nitrogen and oxidizing atmosphere, the major role of oxygen in the degradation process of the organosulfurs has been pointed out. Mercaptans are oxidized to their respective sulfide, disulfide, sulfur dioxide, minor carbonyl compounds and elemental sulfur, whereas tetrahydrothiophene by-products are limited to thiophene, sulfur dioxide, elemental sulfur and traces of sulfone compound. Based on the various observed by-products, the oxidative degradation pathways for the three organosulfurs are presented in this study.
Benoit Boulinguiez, Pierre Le Cloirec, Carbon 48 (2010) 1558-1569

A2363 – Physico–chemical properties of CdO–Al2O3 catalysts. I – structural characteristics

Alumina gels AN6 and AN7 were prepared by precipitation with NaOH from hydrated aluminum sulfate at pH 6 and 7, respectively. A third alumina gel AA7 was similarly prepared, but by precipitation with 30% ammonia. Pure cadmia C8 and C9 were precipitated from cadmium sulfate at pH 8 and 9 using NaOH. Five mechanically mixed gels ACM (1:0.25), ACM (1:0.5), ACM (1:1), ACM (0.5:1) and ACM (0.25:1) were prepared by thoroughly mixing the appropriate molar ratios of AN7 and C8. Also, five coprecipitated gels ACC (1:0.25), ACC (1:0.5), ACC (1:1), ACC (0.5:1) and ACC (0.25:1) were coprecipitated by dropping simultaneously the appropriate volumes of 1 M aluminum sulfate, 1 M cadmium sulfate and 3 M NaOH. Calcination products at 400, 500, 600, 800 and 1000 °C were obtained from each preparation. TG–DTA patterns of uncalcined samples were analyzed and the XRD of all 1000 °C-products and some selected samples calcined at 400–800 °C were investigated. The thermal behaviors of pure and mixed gels depend on the precipitating agent, pH of precipitation, chemical composition and method of preparation. Generally, calcination at temperatures below 800 °C gave poorly crystalline phases. Well crystalline phases are obtained at 800 and 1000 °C. For pure alumina ?-Al2O3 was shown as 400 °C-calcination product that transforms into the ? form around 900 °C and later to ?-Al2O3 as a major phase and ?-Al2O3 as a minor phase at 1000 °C. CdO was shown by 500 °C-calcined cadmia gel that showed color changes with rise of calcination temperature. The most stable black cadmium oxide phase (Monteponite) is obtained upon calcination at 1000 °C. Thousand degree celsius- calcined mixed oxides showed ?-Al2O3, ?-Al2O3, CdAl2O4 and monteponite which dominate depending on the chemical composition.
M.N. Alaya, A.M. Youssef, A. Roumie, R. Grge, Arabian Journal of Chemistry (2010)

A2362 – Oxidative dehydrogenation of butane over substoichiometric magnesium vanadate catalysts prepared by citrate route

Substoichiometric magnesium vanadate catalysts, (Mg–Vi with i = 1, 2, and 3) with different V/Mg atomic ratios and stoichiometric (Mg3V2O8, Mg2V2O7 and MgV2O6), were prepared by citric acid technique. Characterization showed that substoichiometric samples correspond to well-dispersed VO4 units in the MgO matrix. Moreover, taking into account the Raman data, the coexistence of ortho, pyro and meta vanadate phases cannot be discarded. The Mg3V2O8 sample was more active for the oxidative dehydrogenation of n-butane, but less selective to C4 alkenes than the Mg2V2O7 sample. Stoichiometric samples produce mainly 1-butene, whereas for substoichiometric samples butadiene was the major reaction product for reaction temperatures higher than 748 K. The easily reducible VO4 species, and eventually the coexistence of different vanadates phases, appear to be responsible for the catalytic behaviour displayed by the substoichiometric catalysts prepared by citrate technique
Ana Paula Soares Dias, Ljubomir Dimitrov Dimitrov, Margarida Corte-Real Oliveira, Rodica Zavoianu, Auguste Fernandes, Manuel Farinha Portela, Journal of Non-Crystalline Solids 356 (2010) 1488–1497

A2359 – ToF-SIMS studies of the regeneration of Pd/TiO2 catalyst used in hydrodechlorination process

This paper is devoted to the surface studies of deactivation-regeneration process of Pd/TiO2 catalyst used in the hydrodechlorination of CCl4. The samples were prepared by the incipient wetness impregnation method. The time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used as a main analytical tool in these investigations. The advantages of this technique result from high sensitivity of secondary ion mass spectrometers, possibility of detection of not only elemental but also molecular ions and the fact that ToF-SIMS can give information from the upper layer of the investigated material. The results of ToF-SIMS measurements of as prepared, deactivated and regenerated specimens showed that the regeneration of the deactivated sample in the O2 atmosphere among other causes an increase in the ability of the catalyst to the formation of palladium chloride in the next working cycles. A growth in the amount of PdCl2 was accompanied by a decrease in the quantity of surface accessible palladium atoms. It resulted in a more violent drop in the conversion of CCl4 and faster deactivation of the regenerated catalyst. The observations described above indicate that not only carbon deposition and deterioration of the surface area of the catalyst are serious problems in the hydrodechlorination process. The bigger attention should also be focused on the prevention of the formation of palladium chloride in the next working cycles of the catalyst after its regeneration.
Jacek Grams, Jacek Góralski, Paulina Kwintal, International Journal of Mass Spectrometry 292 (2010) 1–6

A2358 – SO2-promoted reduction of NO with NH3 over vanadium molecularly anchored on the surface of carbon nanotubes

Being a major poison, SO2 is often avoided for selective catalytic reduction (SCR) of NO with ammonia at low temperatures. In the present work, we report a V2O5/CNT catalyst with high NO catalytic activities tolerant to SO2, moreover, whose SCR activity is promoted by the SO2 at proper low temperatures. When the reacting temperature is higher than 200 °C, SO2 improves the SCR activity, while it is lower than 200 °C, SO2 deactivates the V2O5/CNT catalysts. It seems that the reacting temperature behaves like a switch, capable of turning on and off the poisoning reactions. Furthermore, the promoting effect of SO2 exhibits a magnified tendency with decreasing V2O5 loadings. TEM and EDS results indicate that the vanadium oxides should molecularly anchor on the surface of CNTs. X-ray photoelectron spectroscopy, ammonia temperature-programmed desorption, temperature-programmed decomposition and temperature-programmed surface reaction results show that the promoting effect of SO2 on SCR activity originates from the formation of sulfate species on the catalyst surface. Based on these findings, a promoting process is also proposed. More importantly, the V2O5/CNTs catalysts show a great stability under the SO2-containing conditions after being operated for 100 h.
Shuli Bai, Jianghong Zhao, Li Wang, Zhenping Zhu, Catalysis Today 158 (2010) 393–400

A2357 – Some features of acetylene hydrogenation on Au-iron oxide catalyst

Hydrogenation of acetylene has been investigated on Au-iron oxide catalysts containing 4.5, 3.0, 5.6 wt% Au prepared by deposition–precipitation (DP) with urea, adsorption of Au sol (SA) and by co-precipitation (CP) of HAuCl4 and Fe(NO3)3, respectively. The latter method produced Au particles supported on 2-line ferrihydrite (Fe5HO8·4H2O). Au/iron oxide catalyst precursors (Au/?-Fe2O3 and Au/2-line ferrihydrite) were characterized by BET, TGA, TPR and XRD, and the Au particle size by TEM measurements. The TPR measurements confirm the ease of transformation of 2-line ferrihydrite to magnetite (Fe3O4) and that the formation of magnetite from ?-Fe2O3 depends strongly on the size of the gold and the supporting oxide particles. Particle size effect of gold has been investigated in semi-hydrogenation of acetylene. Temperature of hydrogen treatment has been observed to play a crucial role in the activity and ethylene selectivity. Au/FeOx samples hydrogen treated at 353–473 K prior to introduction of the reactants (H2:C2H2 = 140, 0.11% C2H2) show very limited over-hydrogenation (ethane formation is less than ?1%) and 2–4% selectivity of oligomer (C4+) formation at 353–473 K. Hydrogen treatment of the samples at T > 573 K but lower than the wüstite (FeO) stability point (?843 K) resulted in partial reduction of Fe3O4 and formation of Fe0. The shift of Au(1 1 1) XRD line to higher 2? provided evidence for the incorporation of Fe0 into the Au particles. Modification of the Au/Fe2O3 perimeter and appearance of Fe0 co-catalyst and Fe–Au ensembles on the surface increased the hydrogenation activity but decreased the selectivity of ethylene formation.
A.Sárkány, Z. Schay, K. Frey, É. Széles, I. Sajó, Applied Catalysis A: General 380 (2010) 133–141

A2347 – Conversion of coal fly ashes into faujasite under soft temperature and pressure conditions: Influence of additional silica

The hydrothermal conversion of a French coal fly ash (FA) into NaX zeolite (faujasite) was studied under soft conditions (30 °C, atmospheric pressure). One used molar composition had previously been found during a preliminary study aiming to determine an optimal composition for the synthesis of NaX from this FA, i.e., 1SiO2:0.36Al2O3:3.8NaOH:72.7H2O, the Al2O3/SiO2 ratio corresponding to the one of the FA, and the zeolitisation procedure consisting only in adding a NaOH solution to the FA. As this composition is much poorer in silica than the one given in the literature for the synthesis from commercial reactants, new experiments were performed with addition of external soluble silica, leading to the following composition: 1SiO2:0.17Al2O3:4.0NaOH:75.5H2O. The zeolitisation kinetics – followed mainly by XRD and N2 adsorption – were compared in presence or absence of additional silica. The addition of silica leads to a final higher content in faujasite (30 wt.% instead of 20–25 wt.%), a higher purity of the zeolitic fraction (co-formation of traces of other more stable zeolites avoided). In presence of external silica, the faujasite crystals are also smaller and display a slightly higher Si/Al framework ratio (1.2 instead of 1.1). One significant point is that the addition of soluble silica leads to a better solubilisation of the FA, about 20% more Al being mobilised. Finally, the zeolisation reaction is delayed when silica is added, the maximum faujasite content being reached after about 50 days instead of about 20 days.
Marion Gross-Lorgouilloux, Michel Soulard, Philippe Caullet, Joël Patarin, Edgar Moleiro, Isabelle Saude, Microporous and Mesoporous Materials 127 (2010) 41–49

A2346 – Coupling dehydrogenation of isobutane to isobutene in the presence of carbon dioxide over NiO/Al2O3 catalyst

Dehydrogenation of isobutane to isobutene in the presence of carbon dioxide was carried out over NiO/Al2O3 catalyst and the effect of K2O additive on its catalytic behavior was investigated. Compared with the reaction in an inert atmosphere, the dehydrogenation of isobutane is coupled with the reverse water-gas shift by conducting the reaction in carbon dioxide, which can then enhance the isobutene yield. The addition of K2O in the NiO/Al2O3 catalyst can decrease its acidity, alleviate the deep reduction of NiO active species during the reaction and then suppress the side reactions like cracking and coke formation; these are helpful to enhance the isobutene yield and to improve the catalyst stability
Ding Jian-fei, Qin Zhang-feng, Chen Shu-wei, Li Xue-kuan, Wang Guo-fu, Wang Jian-guo, Journal of Fuel Chemistry and Technology, Volume 38, Issue 4, August 2010

A2345 – Catalytic dehydrogenation of isobutane in the presence of carbon dioxide over nickel supported on active carbon

The dehydrogenation of isobutane to isobutene was carried out in the presence of carbon dioxide over the catalyst nickel supported on active carbon (AC). The state and property of nickel species (NiOx) in the catalyst are relevant to its calcination temperature, because NiO may be partially reduced to Ni by AC at high temperature. NiO and Ni species are different in the catalytic behaviors; Ni is only effective for direct dehydrogenation of isobutane, while NiO is also highly active for the coupled dehydrogenation with carbon dioxide. Carbon dioxide can significantly enhance the dehydrogenation of isobutane over NiO/AC through keeping NiO species, in situ eliminating hydrogen produced and suppressing coke formation.
Jianfei Ding, Zhangfeng Qin, Xuekuan Li, Guofu Wang, Jianguo Wang, Journal of Molecular Catalysis A: Chemical 315 (2010) 221–225

A2335 – Cyclam complexes of Cu(II) and Co(II) as stationary phases for gas chromatography

New macrocyclic stationary chemically bonded phases were synthesized and tested in gas chromatography conditions. The complexes of 1,4,8,11-tetraazacyclotetradecane with Cu(II) and Co(II) were bonded to the silica support through the (3-chloropropyl)triethoxysilane reactant. The packings obtained were analyzed by diffuse-reflectance ultraviolet-visible spectroscopy (DRUV-Vis), differential thermal gravimetry (DTG), porosimetry, and elementary analysis. Preliminary study of the novel silica gas chromatography (GC) stationary phases containing cyclam complexes was carried out using packed 1/8in. i.d. columns. The study was conducted on: cyclic, linear and branched olefins, aromatic hydrocarbons and ethers. Characterization of interactions between the compounds mentioned and new stationary phases was based upon analysis of Kováts retention indices (I), difference between retention indices for two phases (DeltaI), and molecular retention indices (DeltaM(e)). Results have shown that the new stationary phases interact sufficiently strongly with molecules of high electron density and can be applied in capillary gas chromatography for the analysis of light hydrocarbons.
P. Bielecki,W. Wasiak, Journal of Chromatography A, 1217 (2010) 4648–4654

A2332 – Mesopore constrictions derived from the substitutionally co-packed SBA-15

A highly ordered, substitutionally co-packed, bimodal hexagonal mesoporous silica, ORK-1, with a dual mesopore/constriction size distribution has been synthesized successfully by the co-packing of two different copolymer micelles (amphiphilic triblock copolymer systems) in strong acid media. The materials have a similar but constricted channels (as shown by transmission electron microscopy, powder X-ray diffraction, TGA and N2 adsorption isotherm (BET)) to those of SBA-15 materials. However, real-time UV–Vis absorbance spectra confirm the strongest intra-micellar interaction of two types of copolymer molecules in a binary system occurs when the molar content of these copolymers are equal, i.e. P123:P65 = 0.5:0.5. The stronger the interaction between these copolymers, the shorter the gelation (packing) time is. Both the size and the distribution of the mesopores/constrictions can be adjusted by varying the molar ratio between the surfactants. The size distribution of pores ‘templated’ by the surfactant micelles has been proved to depend on the relative concentrations of the two block copolymers. In particular, the higher the concentration fraction of one of the block copolymers in the solution the larger is the micelles formed there from and so the greater the diameter of the derived pore size in the bimodal porous structure. The lower the concentration fraction of the block copolymer, the smaller the micelles (associated with that copolymer) and the smaller the pore diameter. A mechanism for the formation of these materials is discussed. Evidence suggests that these interacted copolymer surfactants have significant influence on their sol–gel properties and the final mesostrucures.
Lan Chen, Wen-Hua Zhang, Ju Xu, David A. Tanner, Michael A. Morris, Microporous and Mesoporous Materials 129 (2010) 179–188

A2331 – Removal of an analgesic using activated carbons prepared from urban and industrial residues

The removal of an analgesic drug (acetaminophen) from water was investigated using activated carbons prepared from different residues, namely urban wastes (post-consumer plastics), and agro-industrial residues (cork powder and peach stones), comparing their adsorption capacity with that of commercially available carbonaceous adsorbents. The prepared carbon samples were evaluated on the basis of their adsorption capacities and kinetic performances, which were linked with their different properties. The samples prepared from chemical activation of the biomass residues show reasonably high removal efficiencies along with fast rate of adsorption, which are in fact comparable to commercial carbons. The analysis of the carbon samples after adsorbing the analgesic showed that adsorbent–adsorbate affinity is stronger in hydrophobic carbons of basic character that contain a well-developed microporosity. These characteristics are however not sufficient for an overall performance of a carbon in acetaminophen removal. The carbon must also have a well interconnected pore network (to facilitate the accessibility of acetaminophen molecules, thus speeding up adsorption kinetics) and an adequate chemical composition, which ultimately leads to a high adsorption capacity.
I. Cabrita, B. Ruiz, A.S. Mestre, I.M. Fonseca, A.P. Carvalho, C.O. Ania, Chemical Engineering Journal 163 (2010) 249–255

A2329 – Highly basic catalysts obtained by intercalation of La-containing anionic complexes in layered double hydroxides

Nanocomposites have been obtained by intercalation of preformed negatively charged guest La hydroxy citrate colloids into host Mg/Al layered double hydroxides (LDH). These compounds have been used as precursors for La/Mg(Al)O mixed oxides catalysts. The La loading has been controlled by the colloids exchange rate in order to achieve a better dispersion of the lanthanum cations and thus improve the basic properties of the new catalysts. The increase of the d0 0 3 interlayer distance from 0.830 nm in the host LDH to 1.196 nm in the nanocomposites shows that the intercalation has taken place leading to 1.82–11.16 wt% of lanthanum cation loadings. The basic properties of the La/Mg(Al)O(x) mixed oxides were evaluated qualitatively using Hammett indicators and quantitatively by TPD of CO2. Both techniques indicated the presence of strong basic sites. The transesterification of 1-phenylethanol with diethylcarbonate (DEC), which is known to involve strong basic sites, was used to evaluate the catalytic activity of the La/Mg(Al)O(x) mixed oxides. Yields into carbonate product increase with the density of strong basic sites of the catalyst.
Iuliana Cota, Eliana Ramírez, Francisco Medina, Jesús E. Sueiras, Géraldine Layrac, Didier Tichit, Applied Catalysis A: General 382 (2010) 272–276

A2328 – Templated Silica with Increased Surface Area and Expanded Microporosity: Synthesis, Characterization, and Catalytic Application

In this paper, we report a convenient and effective approach to synthesizing mesoporous SBA-15 materials with increased surface area (up to 836.7cm3/g) and expanded microporosity (up to 0.22cm3/g), where the textural properties of the synthesized materials can be systematically controlled. These micro/mesoporous composite materials exhibit excellent performance in catalysis, adsorption and separation. Moreover, the synthesized materials that supported Pd catalysts obtained through impregnation and grafting approaches were tested to explore their flexibility in toluene elimination. Grafting is an effective method to obtain highly dispersed Pd nanoparticles compared with traditional impregnation approach. The catalyst prepared via the grafting procedure possesses higher activity and CO2 selectivity than that was prepared by impregnation method. Moreover, the catalytic performance of synthesized catalysts can be well sustained during the stability tests. Therefore, these novel Pd-supported catalysts are promising materials for effective removal of some types of volatile organic compounds (VOCs) such as toluene.
Chi He, Qin Li, Peng Li, Yufei Wang, Xinyan Zhang, Jie Cheng, Zhengping Hao, Chemical Engineering Journal 162 (2010) 901–909

A2327 – Effect of outgassing temperature on the performance of porous materials

This work illustrates the consequences of an inadequate outgassing temperature of porous materials of different nature (zeolites and activated carbons) on their performance on gas storage and wastewater remediation. Outgassing at low temperature in thermally stable materials leads to an incomplete cleaning of the porous surface; as a result, the gas storage ability based on adsorption isotherms is underestimated. In contrast, outgassing at elevated temperature in temperature-sensitive materials provokes irreversible changes in their composition and structure, which also affects strongly their stability and performance. Two examples illustrating wrong interpretation data on CO2 capture on zeolites and wastewater treatment using activated carbons are addressed. The results show how the performance of a given material can be significantly modified or misunderstood after the outgassing pretreatment.
Alessandro Figini-Albisetti, Leticia F. Velasco, Jose´ B. Parra, Conchi O. Ania, Applied Surface Science 256 (2010) 5182–5186

A2326 – Comprehensive investigation of Pd/ZSM-5/MCM-48 composite catalysts with enhanced activity and stability for benzene oxidation

ZSM-5/MCM-48 composite materials with various acidities have been successfully assembled on zeolite seeds via a two-step crystallization process. The characterization results reveal that the ZSM-5 seeds are present in the framework of the resulting composite materials with its content gradually increasing with the Si/Al molar ratio, and Al atoms prefer the tetrahedral coordination in composite products. The amount of strong acid sites increases as the Si/Al molar ratio decreases, while that of weak acid sites is almost unchanged. The activity tests demonstrate that the catalytic activity of Pd-loaded ZSM-5/MCM-48 composite catalysts is much higher than that of Pd/ZSM-5 and Pd/MCM-48, and all these catalysts are active and stable in the total oxidation of benzene. Both Pd0 and Pd2+ are responsible for the oxidation reaction, and the catalytic activity is closely related to the support acidity, the CO2 desorption capability and the Pd dispersion. This research thus indicates that the novel composite materials have promised as active Pd-supported catalysts in the elimination of volatile organic compound (VOCs).
Chi He, Jinjun Li, Peng Li, Jie Cheng, Zhengping Hao, Zhi-Ping Xu, Applied Catalysis B: Environmental 96 (2010) 466–475

A2325 – Ligand-assisted preparation of highly active and stable nanometric Pd confined catalysts for deep catalytic oxidation of toluene

In this study, mesoporous SBA-15 supported Pd catalysts were synthesized through impregnation and grafting approaches. Moreover, the influences of different solvents (ethanol, H2O, tetrahydrofuran, dimethyl sulphoxide and N,N-dimethylformamide) on the dispersion of supported Pd nanoparticles were also systematically investigated. The prepared materials were comprehensively explored by various techniques, including XRD, EDS, ICP-OES, H2 chemisorption, N2 adsorption/desorption, TG-DSC, FT-IR, TEM and STEM. It is found that the traditional impregnation method has some disadvantages in obtaining highly dispersed Pd active phase. Whereas, the grafting method could highly disperse Pd nanoparticles within the mesoporous channels of support material, and the grafting procedure should be promising in designing highly dispersed Pd particles on the silica-based mesoporous materials. The catalyst prepared via the grafting procedure possesses much higher activity and selectivity than that prepared by impregnation method for deep catalytic oxidation of toluene.
Chi He, Peng Li, Hailin Wang, Jie Cheng, Xinyan Zhang, Yufei Wang, Zhengping Hao, Journal of Hazardous Materials 181 (2010) 996–1003

A2324 – Tuning the hydrophobicity of mesoporous silica materials for the adsorption of organic pollutant in aqueous solution

The ability of various as-prepared and organically modified MCM-41 and HMS mesoporous silica materials to behave as efficient adsorbents for organic pollutants in aqueous solution was investigated by using different surface functionalization procedures, so as to adjust their hydrophilic/hydrophobic balance. The hydrophilic and organophilic properties of the parent silica materials and their corresponding surface functionalized counterparts were studied by using water and toluene adsorption isotherms. Their quantification was determined by the hydrophobic static index value (HIstatic), as well as by the silanol and organic group densities after the functionalization step. A clear correlation could be found between the HIstatic values and either the superficial silanol density, or the amount of organic moieties grafted or incorporated to the silica materials. For the highly organically functionalized samples, the residual superficial silanol groups (<50%) are sufficiently isolated from each other so as to prevent the water capillary condensation within the pores, thereby leading to an increased hydrophobic character of the resulting mesoporous silica. Those hydrophobic samples, for which the water liquid meniscus formation within the mesopores was minimized or avoided, exhibited a storage capacity for an organic pollutant (N,N-diethyl-m-toluamide, DEET) in aqueous solution more than 20 times higher than that of the corresponding unmodified sample, independently of the silica nature (MCM-41 or HMS). For all calcined and silylated samples, the DEET maximum adsorption capacities determined by the Langmuir model could be correlated with the silica surface coverage by trimethylsilyl groups and thus with the remaining silanol amount.
Adeline Trouvé, Isabelle Batonneau-Gener, Sabine Valange, Magali Bonne, Samuel Mignard, Journal of Hazardous Materials 201– 202 (2012) 107– 114

A2323 – Carbon templated SAPO-34 with improved adsorption kinetics and catalytic performance in the MTO-reaction

Transport pores were introduced into a crystalline silicoalumophosphate (SAPO-34) using carbon materials as hard templates. Carbon nanoparticles and carbon nanotubes were added as secondary templates during the hydrothermal synthesis. By using a mixed template (morpholine and TEAOH) in the SAPO-34 synthesis it was possible to maintain the crystallinity, the surface area and decrease the formation of amorphous phase. The obtained materials were characterized with XRD, SEM, NMR, NH3-TPD, EDX and N2-physisorption measurements. n-Butane uptake experiments as well as catalytic test revealed that the type of carbon material is important for the accessibility of the hierarchical pore system. The mesopores created by carbon nanoparticles are located inside the particle but do not form a three-dimensional mesopore network. A significant improvement in the kinetic uptake of n-butane and in the conversion of methanol could be observed for the carbon nanotube-templated materials, containing mesopores accessible from the outside of the particle. Reactivation experiments revealed transport pores to be stable even after several regeneration cycles.
Franz Schmidt, Silvia Paasch, Eike Brunner, Stefan Kaskel, Microporous and Mesoporous Materials 164 (2012) 214–221

A2319 – Copper and chromium modified SBA-15: 11C-radiolabeling catalytic study

Novel 11C-radiolabeling catalytic approach is applied for the characterization of copper and chromium modified SBA-15 materials. The method is based on the selective adsorption of 11C-methanol on different catalytic sites with the detection of the products of the conversion. The high CO2 and methylformate selectivity is related to the activity of CuO and Cr2O3 species, while copper chromate nanoparticles facilitate the formation of dimethoxymethane.
Tanya Tsoncheva, Eva Sarkadi-Priboczki, Microporous and Mesoporous Materials 148 (2012) 1–7

A2318 – Catalytic reduction of NO with decomposed methanol on alumina-supported Mn–Ce catalysts

A series of manganese–ceria supported on alumina catalysts with various Mn/Ce ratios are investigated in both methanol decomposition to CO and hydrogen and SCR of NOx with CO. The study is aimed at the potential application of both reactions in integrated devices, where NOx is reduced with the products of the decomposed methanol. The samples are characterized by nitrogen physisorption, XRD, TEM, XPS, UV–Vis, and TPR. It was established that manganese–ceria supported on alumina catalysts are perspective in both methanol decomposition and NO reduction at temperatures above 723 K, which are typical for exhausted gases from the vehicles and some stationary stations. The best catalytic activity and selectivity to the desired products under these conditions was found for the samples with Mn/Mn + Ce ratio of 0.5 and 0.7. This superior catalytic performance is related to the formation of mixed valence Mn3+/Ce4+ and Mn4+/Ce3+ active sites
I. Spassova, T. Tsontcheva, N. Velichkova, M. Khristova, D. Nihtianova, Journal of Colloid and Interface Science 374 (2012) 267–277

A2310 – Organosilanes affecting the structure and formation of mesoporous cellular foams

Purely siliceous and niobium-containing mesoporous molecular foams (MCFs) were synthesized by modifying a standard synthesis route. This was accomplished by decreasing considerably the content of chloride ions in the gel. The samples prepared under such conditions contained the MCF and SBA-15 phases. Mesostructured cellular foams were modified with (3-mercaptopropyl)trimethoxysilane (MPTMS) and (3-aminopropyl)trimethoxysilane (APTMS) via the direct synthesis, with increased efficiency of formation of the spherical MCF phases. All the materials obtained were characterized by XRD, sorption of nitrogen, FT-IR, UV–Vis, thermogravimetric analysis, 29Si MAS NMR, 13C CP/MAS NMR, and electron microscopy. We demonstrated that organosilanes added at the end of the synthesis procedure play a double role; as a source of the anchored catalytic active species (propylamines and propylsulfonic chains) and a source of methanol released during the interaction between MPTMS (APTMS) and hydrolyzed tetraethyl orthosilicate (TEOS). The methanol obtained in this way acts as a co-surfactant increasing the activity of ethanol released during hydrolysis of TEOS and enhancing the transformation of cylindrical SBA-15 towards the spherical MCF phase. Finally, it was shown that niobium species enhanced the oxidation of thiol groups in MPTMS towards sulfonic species and also affected slightly the morphology of the samples. The presence of niobium moieties did not influence, however, the formation of the pure MCFs mesostructured materials and their structural parameters.
Katarzyna Stawicka, Izabela Sobczak, Maciej Trejda, Bogdan Sulikowski, Maria Ziolek, Microporous and Mesoporous Materials 155 (2012) 143–152

A2309 – Template free synthesis of locally-ordered mesoporous titania and its application in dye-sensitized solar cells

A simple template-free synthesis of unique mesoporous titania materials is reported. The synthesis presented is a good, easy and inexpensive method to obtain both ordered and disordered mesoporous titania with tunable and well defined physicochemical properties such us surface area, porosity and crystallinity. The locally-ordered obtained titania was applied as electrode material in dye-sensitized solar cells. The materials prepared were characterized with both wide and small angle XRD, nitrogen adsorption–desorption isotherms, diffuse reflectance UV-Vis, TEM, HRTEM, FT-IR, TGA and DSC measurements. The presented materials showed good activity in photon-to-current conversion process, with overall photoelectric conversion efficiencies reaching up to 5% with fill factors around 60%
Maciej Zalas, Grzegorz Schroeder, Materials Chemistry and Physics 134 (2012) 170– 176

A2305 – Dehydrogenation of cyclohexanol on copper containing catalysts: The role of the support and the preparation method

SiO2 and Al2O3 supported copper catalysts were prepared by “chemisorption–hydrolysis” or incipient wetness impregnation methods and investigated by XRD, TG-TPR, UV–vis diffuse reflectance and FTIR spectroscopy. Formation of finely dispersed copper oxide species was registered for the samples prepared by “chemisorption–hydrolysis” method, while a significant amount of XRD detectable copper oxide phase is registered for the SiO2 impregnated one. The latter materials possess higher catalytic selectivity in cyclohexanol dehydrogenation to cyclohexanone
M. Popova, M. Dimitrov, V. Dal Santo, N. Ravasio, N. Scotti, Catalysis Communications 17 (2012) 150–153

A2304 – The physico-chemical and catalytic properties of ferrite-containing MCM-41 and SBA-15 materials

Cobalt and iron modified MCM-41 and SBA-15 materials were prepared by incipient wetness impregnation technique and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 physisorption, temperature-programmed reduction (TPR-TGA), UV–Vis diffuse reflectance and Mössbauer spectroscopy. Formation of finely dispersed ferrite and cobalt-oxide species was observed on MCM-41 and SBA-15 supports. It was found that the surface properties of the mesoporous support and the temperature of precursor decomposition determine the type of formed metal oxides, their dispersion, reducibility and the catalytic activity in total oxidation of toluene.
Margarita Popova, Ágnes Szegedi, Károly Lázár, Zoltán Károly, Microporous and Mesoporous Materials 151 (2012) 180–187

A2299 – Nb-doped TiO2/carbon composite supports synthesized by ultrasonic spray pyrolysis for proton exchange membrane (PEM) fuel cell catalysts

In this paper we report the use of both ultrasonic spray pyrolysis and microwave-assisted polyol reduction methods to synthesize Nb-doped TiO2/carbon (25 wt% Nb0.07Ti0.93O2/75 wt% carbon) composite supports and Pt0.62Pd0.38 alloy catalysts, respectively. The physicochemical properties of the synthesized supports and their Pt0.62Pd0.38 supported catalysts are evaluated using several methods including XRD, TEM, BET surface area analysis, TGA, as well as ICP-MS elemental analysis. The electronic conductivities and thermal/chemical stabilities of the supports are also evaluated with respect to their possible use as catalyst supports. Electrochemical measurements for oxygen reduction activity of the Pt0.62Pd0.38 alloy catalysts supported on oxide/carbon composites are also carried out in order to check their suitability for possible PEM fuel cell applications. The results show that 20wt%Pt0.62Pd0.38/25 wt%(Nb0.07Ti0.93O2)-75 wt%C catalysts exhibit enhanced mass activities compared to those of commercially available 48wt% Pt/C and home-made 20wt% Pt62Pd38/C catalysts.
Keerthi Senevirathne, Vladimir Neburchilov, Vanesa Alzate, Ryan Baker, Roberto Neagu, Jiujun Zhang, Stephen Campbell, Siyu Ye, Journal of Power Sources 220 (2012) 1-9

A2295 – Leaching of heavy metals under ambient resembling conditions from hydrotreating spent catalysts

Spent hydrotreating catalysts are not inert to air, humidity and temperature, as the combination of these factors may gradually leach metals from the catalyst causing contamination of land and groundwater. In order to investigate the combined effect of ambient variables on metals leaching, a spent hydrotreating catalyst is placed in a tin can heated at 40–50 °C and then treated for 1000 h under a continuous flow of wet air. Said spent catalyst contains 10.68 wt.% V, 0.43 wt.% Fe, 2.67 wt.% Ni and 3.78 wt.% Mo as well as 14.7 wt.% coke and 19.4 wt.% sulfur, the latter basically in the form of metallic sulfides. During the leaching experiment, samples of spent catalyst are taken at different times to track the evolution of metals and coke/sulfur content. At the end of the test, even though relatively low temperatures are used, Ni is fully removed, Mo and V are partially extracted (around 25% for each metal) while the Fe content increases. Practically no leaching of metals is observed on the sulfur/coke-free fresh catalyst subjected to an identical experimental procedure. The presence of sulfur and coke on the spent catalyst clearly enhances metals leaching. The sulfur oxides produced from the oxidation of metallic sulfides with air, in combination with water, results in the formation of acidic species, which have a strong positive influence in leaching metals from the spent catalyst.
S. Ramírez, P. Schacht, R. Quintana-Solórzano, J. Aguilar, Fuel 110 (2013) 286–292

A2293 – Strategies for copper bis(oxazoline) immobilization onto porous silica based materials

A copper(II) chiral bis(oxazoline) homogeneous catalyst (CuBox) was anchored onto mesoporous materials using three procedures: method 1, first anchoring of the bis(oxazoline) functionalized with 3-iodopropyltrimethoxysilane onto hexagonal mesoporous silica, SBA-15 and silica gel and then copper(II) coordination; method 2, anchoring of the CuBox functionalized with 3-iodopropyltrimethoxysilane onto hexagonal mesoporous silica, SBA-15 and silica gel; and method 3, first anchoring onto silica gel of 3-iodopropyltrimethoxysilane and then anchoring of the CuBox. In methods 1 and 3, the remaining free silanol groups of the silica materials were also capped using trimethylsilane groups. The bis(oxazoline) ligand was also encapsulated onto copper(II) exchanged zeolites NaY and NaUSY as a simpler strategy for the homogeneous catalyst immobilization, method 4. The materials were characterized by ICP–AES, elemental analyzes, 13C and 29Si MAS NMR, FTIR, thermogravimetry and nitrogen adsorption at ?196 °C. The materials were tested as heterogeneous catalysts in the benchmark reaction of cyclopropanation of styrene to check the effect of the immobilization strategy on the catalytic parameters as well as on their reutilization in several catalytic cycles.
Ana Rosa Silva, Hélio Albuquerque, Susana Borges, Renée Siegel, Luís Mafra, Ana P. Carvalho, João Pires, Microporous and Mesoporous Materials 158 (2012) 26–38

A2292 – On the location, strength and accessibility of Brønsted acid sites in hierarchical ZSM-5 particles

Microporous and mesoporous (hierarchical) ZSM-5 samples, prepared by desilication, dealumination and templating with carbon nanoparticles have been characterized by adsorbing benzene, cyclohexane and 1,3,5-trimethylbenzene (mesitylene) to probe the location, the strength and the accessibility of Brønsted acid sites. The mesoporosity introduced by the methods explored resulted in a statistical accommodation of benzene at the channel intersections. Cyclohexane showed the highest strength of physisorption in micro- and mesopores and, thus, probes the largest fractions of acid sites. Mesitylene adsorption showed that mesopores of hierarchical zeolites do not contain Brønsted acid sites. All results indicated that the mesoporosity influences only the accessibility of the acid sites in the ZSM-5 crystals mostly via shortening diffusion pathways, but not the strength of the interaction with the cyclic hydrocarbons. The enhanced transport rates observed for benzene are associated to the decreased pore length inside the mesoporous particles, rather than to changes of the pore structure or the generation of additional sites.
Despina Tzoulaki, Andreas Jentys, Javier Pérez-Ramírez, Kresten Egeblad, Johannes A. Lercher, Catalysis Today 198 (2012) 3– 11

A2289 – Porous clay heterostructures with zirconium for the separation of hydrocarbon mixtures

Porous clays heterostructures (PCHs) are a type of clay based porous solids with potentialities in the separation of aromatic molecules by selective adsorption. Mostly PCHs present silica pores, obtained by the polymerization of tetraethoxysilane or silica modified pores by co-polymerization with other types of ethoxysilanes. In the present work we followed an innovative approach to modify the chemical nature of the pores by introducing zirconium oxide species from two different sources. Samples with specific surface areas between 464 and 891 m2 g?1 and total pore volumes between 0.249 and 0.636 cm2 g?1 were then obtained. The selective adsorption properties of the prepared materials were tested for the separation of binary mixtures of selected aromatic molecules, using a gas-chromatographic method and, in some cases, the samples modified with zirconium presented the more favorable selectivity values.
Moisés L. Pinto, Jaqueline Marques, João Pires, Separation and Purification Technology 98 (2012) 337–343

A2288 – Total catalytic oxidation of toluene using Pd impregnated on hierarchically porous Nb2O5 and Ta2O5 supports

A series of supported Pd catalysts were elaborated using hierarchically porous Nb2O5 and Ta2O5 materials, synthesised with and without a non-ionic surfactant. The deposition of Pd nanoparticles was achieved using the wet impregnation method on calcined supports. The catalytic systems were pre-reduced in hydrogen and investigated for their efficiency in the total oxidation of toluene and found to have increased activity in comparison to a series of reference catalysts based on hierarchically porous TiO2 and ZrO2, with minimal benzene formation. Results have shown how activities are dependent on the support material, synthesis conditions and chemical composition.
J.C. Rooke, T. Barakat, S. Siffert, B.-L. Su, Catalysis Today 192 (2012) 183– 188

A2283 – Porosity development during steam activation of carbon foams from chemically modified pitch

The steam activation of carbon foams obtained after thermo-oxidation treatment of coal tar pitch using inorganic acids (H2SO4 and HNO3), and subsequent low pressure foaming process without stabilization step, was investigated. The characterization of the activated carbon foams showed a strong dependence of the final structure of these materials from the chemical composition of the pitch precursor. This was related to the conditions of thermo-oxidation pre-treatment with inorganic acids, used to modify the composition of the initial pitch. In both cases carbon foams with uniform open cell structures were obtained, although they showed very different properties. When nitric acid was used in the initial thermo-oxidative treatment, the steam activation process of the carbon foam proceeded to a larger extent; the porosity parameters of this sample are twice higher than those obtained when using sulfuric acid. This was attributed to the catalytic effect of H2SO4 during the foaming step, which leads to the formation of dense carbon foams with highly ordered structure as inferred from XRD. At converse, densification of the carbon foam did not occur when using nitric acid in the initial thermo-oxidative treatment; the resulting material displayed labile surface groups decomposing at moderate temperatures, as well as an incipient microporosity, which further increased during the steam activation.
Boyko Tsyntsarski, Bilyana Petrova, Temenuzhka Budinova, Nartzislav Petrov, Leticia F. Velasco, José B. Parra, Conchi O. Ania, Microporous and Mesoporous Materials 154 (2012) 56–61

A2281 – Biodiesel production over thermal activated cerium modified Mg-Al hydrotalcites

Heterogeneous basic catalysts can be used for biodiesel production. The performances of several types of such materials are described in the literature but small attention is given to its deactivation in reaction medium. This paper put in evidence that catalysts are not static identities in the reaction medium, and relates the physical characteristics of fresh and post reaction samples with deactivation mechanisms. Catalysts, tested during the methanolysis of soybean oil, were prepared by thermal activation of Ce modified Mg-Al hydrotalcites (Mg/Al = 3, Ce/Mg < 0.1 atomic ratios). Calcination at 575 °C allows to nanostructured samples with main XRD lines belonging to periclase and cerianite. Additionally, calcined samples containing 3% and 5% of Ce showed hydrotalcite patterns pointed out that cerium promotes the fast rehydration and restructuration. All the prepared samples showed contamination with sodium aluminate which masks the Ce effect on the catalysts basicity due to its strong basicity. In the tested conditions, the catalysts with Ce/Mg > 0.03 (atomic ratio) presented FAME yields higher than 90%. Thermogravimetry analysis of post reaction catalysts evidenced that cerium influences the reaction mechanism. The post reaction catalysts evidenced that surface restructuring occurs during reaction with sizeable change of the elements distribution which as beneficial effect on the catalytic performances
Ana Paula Soares Dias, Joana Bernardo, Pedro Felizardo, Maria Joana Neiva Correia, Energy 41 (2012) 344-353

A2279 – Preparation and characterization of mesoporous silica supported cobalt oxide as a catalyst for the oxidation of cyclohexanol

Cobalt oxide catalysts supported on mesoporous silica SBA-15 were prepared by the “two-solvent” method and compared with analogous catalysts prepared by the more conventional methods of impregnation and adsorption. Cobalt nitrate was used as the precursor. The catalysts were characterized by N2 adsorption–desorption, XRD, FTIR, XPS, TPR, ICP-MS, TEM and DR UV–vis. Their activity for the oxidation of cyclohexanol was determined by GC and GC–MS. The effect of metal loading on the morphology and catalytic activity of the catalysts was investigated. The catalyst with the lowest cobalt content exhibited the highest catalytic activity for cyclohexanol oxidation due to the better accessibility of the reactants to the catalytic sites.
Jamileh Taghavimoghaddam, Gregory P. Knowles, Alan L. Chaffee, Journal of Molecular Catalysis A: Chemical 358 (2012) 79– 88

A2271 – Copper and chromium oxide nanocomposites supported on SBA-15 silica as catalysts for ethylacetate combustion: Effect of mesoporous structure and metal oxide composition

Copper and chromium oxide nanocomposite materials with different Cu/Cr ratio are prepared by deposition on silica host matrices with different textural properties and characterized by XRD, nitrogen physisorption, UV–Vis, FTIR, XPS and TPR-TG. Their catalytic behavior in ethylacetate total oxidation was also studied. A complex effect of Cu/Cr ratio, textural characteristics of the support and reaction medium on the phase composition of the supported active phase was found. Different mechanisms of regulation of loaded metal oxides dispersion depending on the support peculiarities were discussed. The relation between the phase composition and the catalytic properties of various bi-component materials was studied.
Tanya Tsoncheva, Mikael Järn, Daniela Paneva, Momtchil Dimitrov, Ivan Mitov, Microporous and Mesoporous Materials 137 (2011) 56–64

A2270 – 11C-radiolabeling study of methanol decomposition on copper oxide modified mesoporous SBA-15 silica

11C-radiolabeling technique is applied to investigate methanol decomposition on copper oxide modified SBA-15. Nitrogen physisorption, XRD, FTIR, UV–vis and TPR techniques are used for catalyst characterization. Selective adsorption coverage of the catalytic active sites with 11C- and 12C-methanol molecules is carried out and the products of their conversion are followed. The mechanism of methyl formate, methylal and CO2 formation from methanol is discussed
Tanya Tsoncheva, Eva Sarkadi-Priboczki, Applied Surface Science 257 (2011) 6661–6666

A2262 – Hydrophobisation of activated carbon fiber and the influence on the adsorption selectivity towards carbon disulfide

The hydrophobisation of commercial viscose-based activated carbon fiber (ACF) was obtained by grafting vinyltrimethoxysilane (vtmos) on the ACF surface, to improve ACF's adsorption selectivity towards carbon disulfide (CS2) under highly humid condition. The characterizations, including FTIR, 29Si NMR, adsorption/desorption of nitrogen, thermal analysis and elemental analysis, revealed that the vtmos was successfully grafted onto the ACF surface, even though the hydrophobisation caused a partial filling of the porosity along with a slight decrease in the surface area. The efficiency of the hydrophobisation modification was evaluated by both equilibrium and dynamic adsorption experiment of water vapor and CS2. The equilibrium adsorption results indicated that the hydrophobisation modifications accounted for a decrease of both the amounts of water and CS2 adsorbed by the hydrophobised ACF. However, dynamic adsorption found that the adsorption performance was improved under highly humid condition, evidencing that hydrophobisation improved the hydrophobicity of the ACF surface and enhanced the adsorption selectivity towards CS2.
Zunyuan Xie, Feng Wang, Ning Zhao, Wei Wei, Yuhan Sun, Applied Surface Science 257 (2011) 3596–3602

A2259 – Hydrosilylation of n-alkenes and allyl chloride over platinum supported on styrene–divinylbenzene copolymer

Catalytic performance of styrene–divinylbenzene copolymer-supported platinum catalyst of high crosslinking degree and high surface area was studied in reactions of hydrosilylation of allyl chloride, 1-octene and 1-butene. The catalyst has shown considerably greater stability of catalytic activity than classical active carbon-supported catalyst. In experiments on repeated use of catalysts, the decrease in catalytic activity for hydrosilylation of liquid double bond-containing compounds proceeding in the presence of the copolymer-supported and carbon-supported platinum was considerably smaller in the case of the former catalyst. Bimetallic Pt–Cu catalyst on polymeric support appeared to be considerably less active than monometallic catalyst.
Agata Wawrzynczak, Micha? Dutkiewicz, Jacek Gulinski, Hieronim Maciejewski, Bogdan Marciniec, Ryszard Fiedorow, Catalysis Today 169 (2011) 69–74

A2258 – New catalysts for biodiesel additives production

Mesoporous silicate and metallosilicate (Al or Nb) materials of SBA-15 type were prepared in the presence of MPTMS, i.e. (3-mercaptopropyl)trimethoxysilane, and hydrogen peroxide. The samples prepared were characterised by different techniques (N2 adsorption/desorption, XRD, XRF, elemental analysis, thermal analysis, FTIR, UV–Vis) and applied as catalysts in glycerol esterification with acetic acid. The impact of different factors such as temperature, glycerol to acetic acid molar ratio, and metal concentration on the course and yield of glycerol esterification was examined. The role of niobium in the formation of sulphonic species was considered and discussed. The most important finding is that niobium source present in the SBA-15 synthesis gel together with MPTMS and H2O2 improves the efficiency of –SH oxidation towards sulphonic species and increases the stability of the modifier (oxidised MPTMS), which results in increased activity and selectivity of the catalysts to triacetylglycerol in esterification of glycerol.
Maciej Trejda, Katarzyna Stawicka, Maria Ziolek, Applied Catalysis B: Environmental 103 (2011) 404–412

A2253 – Desilication of MOR zeolite: Conventional versus microwave assisted heating

MOR zeolites were modified via desilication treatments with NaOH, under conventional and microwave heating. The samples were characterized by powder X-ray diffraction, 27Al and 29Si NMR spectroscopy, TEM and N2 adsorption at ?196 °C. The acidity of the samples and the space available inside the pores were evaluated through a catalytic model reaction, the isomerization of m-xylene, for which the profiles of the coke thermal decomposition were also analyzed. Powder X-ray diffraction and 29Si and 27Al MNR results show that in comparison with conventional heating, microwave irradiation (a less time consuming process) leads to identical amount of Si extraction from the zeolite framework. With this treatment, in addition to the customary mesopores development promoted by conventional heating, a partial conversion of the zeolite microporosity into larger micropores, is observed. The microwave irradiated and conventionally heated samples show different catalytic behavior in the m-xylene isomerization model reaction. It was observed that, by controlling the experimental conditions, it is possible to obtain samples with catalytic properties closer to the parent material, which is also confirmed by the respective coke analysis.
V. Paixão, R. Monteiro, M. Andrade, A. Fernandes, J. Rocha, A.P. Carvalho, A. Martins, Applied Catalysis A: General 402 (2011) 59– 68

A2245 – Liquid and gas-phase Meerwein–Ponndorf–Verley reduction of crotonaldehyde on ZrO2 catalysts modified with Al2O3, Ga2O3 and In2O3

A series of catalysts consisting of ZrO2 modified with Al, Ga and In by coprecipitation with their precursor salts or impregnation of previously synthesized ZrO2 with the nitrates of the metals was prepared. The solids thus obtained were characterized using a wide range or techniques including TG/DTG; XRD, SEM-EDAX, ICP-MS, FTIR and FT-Raman spectroscopies; and nitrogen adsorption–desorption at 77 K. The catalysts prepared by impregnation were found to contain Al, Ga and In nitrates while those obtained by coprecipitation contained Al2O3, Ga2O3 and In2O3. The catalysts were analyzed for surface acidity and basicity by thermal programmed desorption of pyridine and CO2, respectively. The impregnated solids calcined at 300 °C exhibited low basicity and moderate acidity due to Brønsted and Lewis sites. The coprecipitated solids were slightly more acid and basic than their impregnated counterparts, their acidity being mainly due to the presence of Brønsted sites. Both types of solids were used as catalysts in the Meerwein–Ponndorf–Verley reduction of crotonaldehyde with 2-propanol as hydrogen donor. The impregnated solids calcined at 300 °C (particularly the Ga/ZrO2 catalyst) were the most active and selective ones in the liquid phase reaction. The selectivity towards 2-butenol in the reaction in the gas phase was high at temperatures up to 250 °C, above which it dropped in a rapid manner. Again, the impregnated solids calcined at 300 °C were the most active and selective systems in the process (particularly Ga/ZrO2).
Juan F. Minambres, María A. Aramendía, Alberto Marinas, José M. Marinas, Francisco J. Urbano, Journal of Molecular Catalysis A: Chemical 338 (2011) 121–129

A2242 – Highly effective CuO/Fe(OH)x catalysts for selective oxidation of CO in H2-rich stream

Ferric hydroxide supported copper oxide (CuO/Fe(OH)x) catalysts were prepared with a simple co-precipitation method and used for selective oxidation of CO in H2-rich gas. The effect of calcination temperatures and Cu loadings on the activity as well as the durability of the catalyst was investigated. When the calcination temperature was 200 °C and the Cu loading was ranging from 7.2 to 17.3 wt%, the catalyst gave the best performance with total conversion of CO achievable in a wide temperature window from 110 °C to 150 °C. To reveal the reason for the high activity of the catalysts, a variety of characterization techniques were employed. The results of XRD and TG–DTA indicated that the catalysts were amorphous even after being calcined at 400 °C, which gave rise to large surface areas. HRTEM and XPS examinations indicated that the surface copper species were Cu2O with particle size of smaller than 5 nm. In situ DRIFT and FT-IR results showed that the reduction of Cu2+ in the composite occurred even below room temperature when exposed to CO. The significant reducibility might contribute to the high activity of the catalysts.
Botao Qiao, Aiqin Wang, Jian Lin, Lin Li, Dangsheng Su, Tao Zhang, Applied Catalysis B: Environmental 105 (2011) 103–110

A2238 – Deactivation and regeneration studies of a PdSb/TiO2 catalyst used in the gas-phase acetoxylation of toluene

A PdSb/TiO2 catalyst was subjected to selective gas-phase acetoxylation of toluene (Tol) to benzyl acetate (BA). The catalyst showed low initial activity, which increased with time and displayed maximum activity after 6 h on-stream. The catalyst exhibited stable performance for the next 25 h on-stream and then started to deactivate rapidly. Carbon analysis pointed to coke deposition as a main reason for the loss of catalytic activity. Regeneration at 250 °C could restore the catalyst activity but showed rapid deactivation again in a subsequent run. Regenerative treatment at 300 °C was much more effective not only in restoring the performance but also in maintaining relatively good stability of the catalyst. However, treatment at 350 °C and higher was found to be ineffective in restoring catalytic activity. This surprising behavior of the catalyst was studied in detail with various techniques such as XRD, TEM, and XPS analysis. XRD data give evidence on shifting of Pd reflection to lower 2? values and the splitting into two parts pointing to different types of Pd species. The surface ratio of Pd0/PdO of 1 seems to be essential for better performance as revealed by XPS analysis. Surprisingly, this ratio is significantly changed in the deactivated catalyst. Moreover, only metallic Pd species were found on the catalyst surface of this deactivated solid. In addition, regeneration at 300 °C could restore PdO concentration to a greater extent, while the one regenerated at 350 °C could not restore the PdO proportion. This behavior is also believed to be one of the reasons for the unproductive regeneration of deactivated catalyst at 350 °C. Furthermore, Pd0, PdO, and Sb synergy is needed for stable and high performance of the catalyst.
N. Madaan, S. Gatla, V.N. Kalevaru, J. Radnik, B. Lücke, A. Brückner, A. Martin, Journal of Catalysis 282 (2011) 103–111

A2237 – Factorial design analysis for sorption of zinc on hydroxyapatite

A factorial design was employed to evaluate the quantitative removal of zinc from aqueous solutions on synthesized hydroxyapatite. The experimental factors and their respective levels studied were the initial zinc concentration in solution (35 ? CZn ? 85 mg/L), adsorbent dosage (4.5 ? Csusp ? 9.5 g/L), Ca/P molar ratio (1.667 ? Ca/P ? 2) and calcination temperature of hydroxyapatite (600 ? TCal ? 800 °C). The adsorption parameters were analysed statistically by means of variance analysis by using the STATISTICA software. The experimental results and statistical analysis show that increasing in the calcination temperature from 600 to 800 °C decrease the zinc adsorption whereas the increase of adsorbent dosage increases it. Based on the analysis of variance and the factorial design of experiments, adsorbent dosage has a positive effect on the removal of zinc, whereas zinc concentration, Ca/P molar ratio and calcination temperature have a negative effect on this process. The factorial results also demonstrate the existence of statistically significant binary interactions of the experimental factors. The experimental results were fitted to the Langmuir and Freundlich equations to find out adsorption capacities. In most cases, the results indicate that the sorption data fits well in the Freundlich isotherm model. The results of XRD analysis, pHPZC and pHFinal values indicated that ion exchange and dissolution/precipitation mechanisms predominate for the sorption of zinc on our hydroxyapatite.
S. Meski, S. Ziani, H. Khireddine, S. Boudboub, S. Zaidi, Journal of Hazardous Materials 186 (2011) 1007–1017

A2232 – The influence of catalytic activity on the response of Pt/SnO2 gas sensors to carbon monoxide and hydrogen

The article presents the results of research studies on ceramics SnO2 sensors with Pt catalysts. The role of catalysis in gas sensing mechanisms was investigated. In order to obtain samples with different catalytic activity but with identical Pt loading, the Pt/SnO2 catalysts were calcined at different temperatures (400–800 °C). Structural analysis of these samples was performed. Among the sensors manufactured with Pt/SnO2, the highest sensitivity was shown for the sensor obtained with Pt/SnO2 sample sintered at 800 °C. The correlation between catalytic activity and sensor sensitivity is given.
Ireneusz Kocemba, Jacek Rynkowski, Sensors and Actuators B 155 (2011) 659–666

A2220 – Fluidized bed plasma for pre-treatment of Co-ferrierite catalysts: An approach to NOx abatement

Replacement of calcination procedures used during catalyst preparation, by a plasma treatment, was studied over a Co-ferrierite (Co-FER) catalyst. The catalyst was tested in the NOx selective catalytic reduction reaction. A combination of UV–Vis spectroscopy and TG analysis revealed the presence of ammonium ions on the untreated and plasma Co-FER samples but not on the calcined one. Therefore, it can be concluded that the plasma treatment was not able to replace the thermal calcination step. The evaluation of catalyst behaviour was performed both under temperature programmed surface reaction (TPSR) and under steady-state conditions at different temperatures. NO oxidation tests showed that, during TPSR runs, calcined catalyst produces more NO2 than plasma catalyst. NOx consumption during TPSR of plasma catalyst confirms that precursors used on the ion-exchange procedure are still present on the catalyst even after the plasma treatment, reacting with NO to produce R-NOx, N2O and N2. Concerning deNOx tests using ethanol as reducing agent, TPSR tests showed higher NOx conversions over untreated and plasma catalysts due to the presence of ammonium and acetate precursors on these catalysts. Untreated, plasma and calcined catalysts present the same NOx and COx conversions in isothermal tests.
R. Bartolomeu, M. Foix, A. Fernandes, M. Tatoulian, M.F. Ribeiro, C. Henriques, P. da Costa, Catalysis Today 176 (2011) 234– 238

A2217 – Catalytic activities of cobalt, nickel and copper ferrospinels for sulfuric acid decomposition: The high temperature step in the sulfur based thermochemical water splitting cycles

The catalytic decomposition of sulfuric acid is the most endothermic step of the sulfur based water splitting thermochemical cycles, which are promising technologies for large scale hydrogen production in future. In the present study the catalytic activities of three ferrospinels AFe2O4 (A = Co, Ni, Cu) were evaluated for high temperature sulfuric acid decomposition reaction. Catalyst characterization by Mössbauer spectroscopy confirmed the occupancy of octahedral and tetrahedral sites by Fe3+ ions in all three inverse spinels. The temperature programmed reduction studies revealed that the reducibility of Fe3+ was greatly enhanced in CuFe2O4 as compared to other ferrites. Copper ferrite was found to be the most active catalyst for the reaction with ?78% conversion at 800 °C. Presence of sulfate species on the spent catalysts was revealed by an ex situ analysis of the spent catalyst samples by FTIR, SEM and evolved gas analysis (EGA). FTIR spectra of all the three spent catalyst samples exhibit four prominent peaks in the region 950–1200 cm?1, which is an indicative of C2v symmetry and bidentate sulfate coordination. A plausible mechanism for the sulfuric acid decomposition over spinel ferrites was proposed via the metal sulfate formation and then decomposition followed with an oxygen evolution step with the sulfate decomposition being the rate determining step at higher temperatures. EGA showed evolution of SO2 as a decomposition product from existed sulfate of spent catalysts at high temperatures, with the rate of SO2 evolution following the order: CuFe2O4 > NiFe2O4 > CoFe2O4. The enhanced rate of decomposition of the sulfates of copper ferrite can be attributed to the higher electronegativity of Cu2+ as compared to Ni2+ and Co2+, which renders the S–O bond in the mixed metal sulfate weaker than others and thus more susceptible to dissociation. The lower thermal stability of sulfate and better reducibility are responsible for the improved catalytic properties of copper ferrite among the three ferrospinels investigated for sulfuric acid decomposition.
A.M. Banerjee, M.R. Pai, S.S. Meena, A.K. Tripathi, S.R. Bharadwaj, International Journal of Hydrogen Energy 36 (2011) 4768-4780

A2213 – Adsorption performance of VOCs in ordered mesoporous silicas with different pore structures and surface chemistry

Ordered mesoporous silicas with different pore structures, including SBA-15, MCM-41, MCM-48 and KIT? 6, were functionalized with phenyltriethoxysilane by a post-synthesis grafting approach. It was found that phenyl groups were covalently anchored onto the surface of mesoporous silicas, and the long-range ordering of the mesoporous channels was well retained after the surface functionalization. The static adsorption of benzene and the dynamic adsorption of single component (benzene) and bicomponent (benzene and cyclohexane) on the original and functionalized materials were investigated. As indicated by the adsorption study, the functionalized silicas exhibit improvement in the surface hydrophobicity and affinity for aromatic compounds as compared with the original silicas. Furthermore, the pore structure and the surface chemistry of materials can significantly influence adsorption performance. A larger pore diameter and cubic pore structure are favorable to surface functionalization and adsorption performance. In particular, the best adsorption performance observed with phenyl-grafted KIT-6 is probably related to the highest degree of surface functionalization, arising from the relatively large mesopores and bi-continuous cubic pore structure which allow great accessibility for the functional groups. In contrast, functionalized MCM-41 exhibits the lowest adsorption efficiency, probably owing to the small size of mesopores and 1 D mesoporous channels.
Baojuan Dou, Qin Hu, Jinjun Li, Shizhang Qiao, Zhengping Hao, Journal of Hazardous Materials 186 (2011) 1615–1624

A2211 – Synthesis, characterization and photocatalytic activity of TiO2 supported natural palygorskite microfibers

This study deals with the synthesis of TiO2 supported Moroccan palygorskite fibers and their use as photocatalyst for the removal of Orange G pollutant from wastewater. The TiO2-palygorskite nanocomposite synthesis was accomplished according to a colloidal route involving a cationic surfactant as template (hexadecyltrimethylammonium bromide) assuring hence organophilic environment for the formation of TiO2 nanoparticles. The clay minerals samples were characterized before and after functionalization with TiO2. Anatase crystallizes above ca. 450 °C and remarkably remains stable up to 900 °C. In contrast, pure TiO2 xerogel obtained from titanium tetraisopropoxide (TTIP) showed before calcination a nanocrystalline structure of anatase. By increasing the temperature, anatase readily transforms into rutile beyond 600 °C. The remarkable stability at high temperature of anatase particles immobilized onto palygorskite microfibers was due to the hindrance of particles growth by sintering. Homogeneous monodisperse distribution of anatase particles with an average size of 8 nm was found by TEM and XRD onto palygorskite fibers. This anatase particle size remains below the nucleus critical size (ca. 11 nm) required for anatase–rutile transition. The TiO2 supported palygorskite sample annealed in air at 600 °C for 1 h exhibits the highest photocatalytic activity towards the degradation of Orange G compared to nanocomposite samples prepared under different conditions as well as pure TiO2 powders obtained from the xerogel route or commercially available as Degussa P25.
L. Bouna, B. Rhouta, M. Amjoud, F. Maury, M.-C. Lafont, A. Jada, F. Senocq, L. Daoudi, Applied Clay Science 52 (2011) 301–311

A2210 – Heterogeneous Photodecolorization of Methyl Green Catalyzed by Fe(II)-o-Phenanthroline/Zeolite Y Nanocluster

The potential of Fe(II)-orthophenatrolin, as doped with synthetic zeolite Y nanocluster (Na-Y) via complexation process, after wet impregnation of parent zeolite with FeSO4 aqueous solution, was studied as a photocatalyst in decolorization of Methyl Green (MG) under UV irradiation. The characterization of the synthesized zeolite nanocluster and the prepared catalyst was studied using X-ray powder diffraction (XRD), infrared spectroscopy (FT-IR), thermal analysis, and SEM methods. The dye photodecolorization process was studied considering the influence of experimental parameters and it was observed that photoreactivity of the photocatalyst was varied with catalyst amount, initial dye concentration, pH of dye solution, temperature, and the presence of KBrO3. The optimal experimental parameters were obtained as follows: catalyst amount: 1?gL?1, dye concentration: 40?ppm, pH: 9, and active component value: 100?mg Fe(II)-orthophenatrolin per g catalyst. The reusability of the intended catalyst was also investigated. The degradation process obeyed first-order kinetics.
Alireza Nezamzadeh-Ejhieh, Elahe Shahriari, International Journal of Photoenergy Volume 2011, Article ID 518153

A2208 – Effect of functionalized carbon as Pt electrocatalyst support on the methanol oxidation reaction

FTIRS and XPS spectra showed that after oxidative treatments using H2SO4 + HNO3 and HNO3 solutions the Vulcan XC-72R carbon support has been found to be more hydrophilic and richer in oxygen-containing functional groups. Consequently, the Pt electrocatalyst prepared on those functionalized carbon materials further to having good dispersion of metal presented a significant improvement of the electrocatalytic activity due to the synergistic effect between the metal nanoparticles and oxygenated groups on functionalized carbon.
J.R.C. Salgado, R.G. Duarte, L.M. Ilharco, A.M. Botelho do Rego, A.M. Ferraria, M.G.S. Ferreira, Applied Catalysis B: Environmental 102 (2011) 496–504

A2207 – Centimeter-sized zeolite bodies of intergrown crystals: Preparation, characterization and study of binder evolution

The control of the inter-particle porosity in polycrystalline zeolite bodies remains a challenge. The present study reports on the preparation of centimeter-sized zeolite bodies (32 × 2 mm pellets) with reduced inter-particle porosity. The bodies were prepared by assembling zeolite colloidal nanocrystals with monomodal particle size distribution and sub-colloidal aluminum hydroxide binder. A secondary growth treatment under hydrothermal conditions was performed in order to fill up the inter-particle voids and obtain polycrystalline zeolite materials with textural characteristics close to those of single zeolite crystals. Initial material, intermediates and ultimate product were studied with a combination of complementary methods revealing a substantial reduction even an elimination of the inter-particle porosity. Particular attention was paid to the chemical evolution of the binder and the migration of aluminum species, employing X-ray powder diffraction, 27Al-MAS, 27Al-3QMAS NMR and X-ray fluorescence spectroscopy analyses. Evidences for insertion of aluminum from the binder into the zeolite framework during secondary growth step were found. Consequently the ultimate pellets comprised aluminum-rich zeolite beta crystals and very low binder content.
Lama Itani, Valentin Valtchev, Joël Patarin, Séverinne Rigolet, Feifei Gao, Gérard Baudin, Microporous and Mesoporous Materials 138 (2011) 157–166

A2205 – The effect of heat treatment on phase formation of copper manganese oxide: Influence on catalytic activity for ambient temperature carbon monoxide oxidation

The auto-reduction of copper and manganese acetates has been investigated using in situ X-ray diffraction and thermogravimetric analysis, with the intention of manipulating the phenomena to tailor specific phase formation for synthesising catalysts. Subsequently catalysts prepared in this controlled manner were evaluated for ambient temperature CO oxidation. The decomposition of mixed copper and manganese acetate systems was controlled to form MnOx-supported Cu or CuMnOx spinel structures, depending on the oxygen concentration and flow conditions during the heat treatment. Catalyst precursors were prepared by physical grinding and by a supercritical CO2 anti-solvent precipitation process. The use of supercritical anti-solvent precipitation allows for the formation of well-mixed metal acetates that decompose to form active spinel CO-oxidation catalysts or small copper nano-particles supported on MnOx, depending on the oxygen content of the heat treatment atmosphere. The ability to tune oxidation state and phase composition of catalysts is a key preparation parameter for controlling the activity and provides insight into the active sites for CO oxidation.
Simon A. Kondrat, Thomas E. Davies, Zhongling Zu, Paul Boldrin, Jonathan K. Bartley, Albert F. Carley, Stuart H. Taylor, Matthew J. Rosseinsky, Graham J.Hutchings , Journal of Catalysis 281 (2011) 279–289

A2204 – Synthesis and characterization of PVAm/SBA-15 as a novel organic–inorganic hybrid basic catalyst

Composite polyvinyl amine/SBA-15 (PVAm/SBA-15) in various amounts of SBA-15 were prepared and characterized. The physical and chemical properties of PVAm/SBA-15 were investigated using FT-IR, XRD, BET, SEM and TGA techniques. The catalytic performance of each material was determined for the Knoevenagel condensation reaction between carbonyl compounds and ethyl cyanoacetate in the presence of ethanol as solvent. The effects of reaction temperature, solvent and the amounts of catalyst as well as recyclability of the catalyst were investigated. The catalyst used for this synthetically useful transformation showed a considerable degree of reusability besides being very active.
Roozbeh Javad Kalbasi, Majid Kolahdoozan, Mahsa Rezaei, Materials Chemistry and Physics 125 (2011) 784–790

A2203 – Synthesis and characterization of BEA-SO3H as an efficient and chemoselective acid catalyst

BEA zeolite was synthesized under hydrothermal condition and modified with various amounts of chlorosulphonic acid. It was characterized by XRD, XRF, FT-IR, BET, thermogravimetric analysis and SEM techniques. Catalytic activity of BEA-SO3H was tested for the synthesis of 1,1-diacetates from a variety of aromatic and aliphatic aldehydes including those carrying electron donating or withdrawing substituents by acetic anhydride. At optimized conditions, The BEA-SO3H (28 wt.%) catalyst showed good yield at very short time for the synthesis and deprotection of 1,1-diacetates. Furthermore, BEA-SO3H was found to be recyclable for the protection of aldehydes with acetic anhydride under solvent-free and room temperature conditions. This method is a green approach for the protection of aldehydes in the presence of ketones.
Roozbeh Javad Kalbasi, Ahmad Reza Massah, Anahita Shafiei, Journal of Molecular Catalysis A: Chemical 335 (2011) 51–59

A2202 – Synthesis, characterization and catalytic activity studies of Pd-based supported nanoparticle catalyst anchoring on poly(N-vinyl-2-pyrrolidone) modified CMK-3

Pd nanoparticle-poly(N-vinyl-2-pyrrolidone)/CMK-3 (Pd-PVP/CMK-3) composite was prepared by in situ polymerization method which was effectively employed as a novel heterogeneous catalyst for the Suzuki–Miyaura cross-coupling reaction. The physical and chemical properties of Pd nanoparticle-PVP/CMK-3 were investigated using FT-IR, XRD, BET, UV–vis, TEM and TGA techniques. The reaction was carried out between aryl halides and phenylboronic acid in the presence of water at room temperature. The stability of the catalyst was good and could be reused 10 times without much loss of activity in Suzuki–Miyaura reaction.
Roozbeh Javad Kalbasi, Neda Mosaddegh, Materials Chemistry and Physics 130 (2011) 1287– 1293

A2201 – Synthesis and characterization of poly(4-vinylpyridine)/MCM-48 catalyst for one-pot synthesis of substituted 4H-chromenes

In this paper, we wish to report the synthesis and characterization of poly(4-vinylpyridine) supported on MCM-48 by in situ polymerization of 4-vinylpyridine in the presence of MCM-48. This catalyst was effectively employed as a novel heterogeneous basic catalyst for the one-pot synthesis of 4H-chromenes in aqueous medium. This catalyst was easily prepared, and showed considerable level of reusability.
Roozbeh Javad Kalbasi, Neda Mosaddegh, Catalysis Communications 12 (2011) 1231–1237

A2200 – Synthesis and characterization of polymer/microporous molecular sieve nanocomposite as a shape-selective basic catalyst

This paper reports the preparation and characterization of poly(4-vinylpyridine)/AlPO4-11 nanocomposite and its application in Knoevenagel condensation as a novel basic catalyst. The catalyst was characterized by XRD, XRF, FT-IR, TGA, BET, SEM, and back titration using NaOH and TPD techniques. Several AlPO4-11 with different Al/P ratios were prepared, and the effect of the Al/P ratio on the surface properties and acidity of the support were studied. The use of AlPO4-11 as a new supporting material for the Poly(4-vinylpyridine) was tested for the Knoevenagel condensation. Excellent yields at room temperature in aqueous and solvent-free conditions were obtained by this nanocomposite. Accordingly, the catalyst showed shape selectivity in the Knoevenagel reaction. It was observed that the activity of the catalyst just decreased to 90% after five regeneration processes were performed.
Roozbeh Javad Kalbasi, Elham Izadi, C. R. Chimie 14 (2011) 1002–1013

A2197 – 2.8NiO–H1.8Ni0.6(OH)MoO4—Novel nanocomposite material for the reactive adsorption of sulfur-containing molecules at moderate temperature

It has been found that a poorly crystalline green precipitate that forms in boiling ammonia solution of Ni(NO3)2 and (NH4)6Mo7O24 yields on annealing a Ni-rich material (Ni/Mo = 3.4) containing slit shaped mesopores and exhibiting the BET surface area of 230 m2/g. Characterization of the material by TGA, XRD, TEM, SEM, and EXAFS allowed to determine that it is a nanocomposite consisting of Ni–Mo (hydro)oxide layers H1.8Ni0.6(OH)MoO4 which are pillared by NiO nanoparticles (D = 3 nm). The structure of the layers appears to be similar to that found in the previously described crystalline molybdate (NH4)HNi2(OH)2(MoO4)2 prepared in the similar conditions. The obtained nanocomposite 2.8NiO–H1.8Ni0.6(OH)MoO4 can be completely reduced in H2 flow at 300 °C yielding unsupported Ni3.4Mo bimetallic nanoparticles (D = 3.6 nm) which are stable towards sintering. The material shows remarkable activity in a moderate temperature reactive adsorption of thiophene: at 300 °C the rate of its sulfidation in the presence of thiophene is an order of magnitude higher than that of conventional Ni/ZnO sorbent. Such increase of activity is attributed to formation (after partial sulfidation) of the mixed Ni–Mo–S phase, which is known to be highly active in catalytic hydrodesulfurization of sulfur-containing molecules. Also, due to its open structure the nanocomposite reacts rapidly and completely with H2S even at 200 °C, while only the surface sulfidation is observed for ZnO nanoparticles under the same conditions.
Jonathan Skrzypski, Igor Bezverkhyy, Olga Safonova, Jean-Pierre Bellat, Applied Catalysis B: Environmental 106 (2011) 460– 468

A2191 – Silylated Co/SBA-15 catalysts for Fischer–Tropsch synthesis

A series of silylated Co/SBA-15 catalysts were prepared via the reaction of surface Si–OH of SBA-15 with hexamethyldisilazane (HMDS) under anhydrous, vapor-phase conditions, and then characterized by FT-IR, N2 physisorption, TG, XRD, and TPR-MS. The results showed that organic modification led to a silylated SBA-15 surface composed of stable hydrophobic Si–(CH3)3 species even after calcinations and H2 reduction at 673 K. Furthermore, the hydrophobic surface strongly influenced both metal dispersion and reducibility. Compared with non-silylated Co/SBA, Co/S-SBA (impregnation after silylation) showed a high activity, due to the better cobalt reducibility on the hydrophobic support. However, S-Co/SBA (silylation after impregnation) had the lowest FT activity among all the catalysts, due to the lower cobalt reducibility along with the steric hindrance of grafted –Si(CH3)3 for the re-adsorption of ?-olefins
Lihong Jia, Litao Jia, Debao Li, Bo Hou, Jungang Wang, Yuhan Sun, Journal of Solid State Chemistry 184 (2011) 488–493

A2189 – Calcium-based sorbents behaviour during sulphation at oxy-fuel fluidised bed combustion conditions

Sulphur capture by calcium-based sorbents is a process highly dependent on the temperature and CO2 concentration. In oxy-fuel combustion in fluidised beds (FB), CO2 concentration in the flue gas may be enriched up to 95%. Under so high CO2 concentration, different from that in conventional coal combustion with air, the calcination and sulphation behaviour of the sorbent must be defined to determine the optimum operating temperature in the FB combustors. In this work, the SO2 retention capacity of two different limestones was tested by thermogravimetric analysis at typical oxy-fuel conditions in FB combustors. The effect of the main operating variables affecting calcination and sulphation reactions, like CO2 and SO2 concentrations, temperature, and sorbent particle size, was analysed. It was observed a clear difference in the sulphation conversion reached by the sorbent whether the sulphation takes place under indirect or direct sulphation, being much higher under indirect sulphation. But, in spite of this difference, for a given condition and temperature, the CO2 concentration did not affect to the sulphation conversion, being its major effect to delay the CaCO3 decomposition to a higher temperature. For the typical operating conditions and sorbent particle sizes used in oxy-fuel FB combustors, the maximum sorbent sulphation conversions were reached at temperatures of about 900 °C. At these conditions, limestone sulphation took place in two steps. The first one was controlled by diffusion through porous system of the particles until pore plugging, and the second controlled by the diffusion through product layer. As a consequence, the maximum sulphation conversion increased with decreasing the particle size and increasing the SO2 concentration.
Francisco García-Labiano, Aránzazu Rufas, Luis F. de Diego, Margarita de las Obras-Loscertales, Pilar Gayán, Alberto Abad, Juan Adánez, Fuel 90 (2011) 3100–3108

A2161 – Effect of Pt-loaded carbon support nanostructure on oxygen reduction catalysis

This work demonstrates the impact of the nanostructure (pore size, wall thickness and wall crystallinity) of several carbon materials on their performance as oxygen reduction reaction (ORR) catalyst supports in PEM fuel cell applications. Two different mesoporous carbons [a surfactant-templated ordered mesoporous carbon (OMC) with 1.6 and 3.3 nm pores, and a silica colloid-imprinted carbon (CIC) with a 15 nm pore size], selected as being the most active in their class, were compared with microporous Vulcan Carbon. After loading with 20 and 40% Pt, both 3D transmission electron microscopy and electron tomography revealed that the Pt nanoparticles reside inside the majority of the pores of the OMC and CIC, but are located only on the outer surface of the VC particles. ORR performance studies on a rotating glassy carbon disc electrode in O2-saturated 0.5 M H2SO4 showed that the Pt-loaded CIC outperforms both Pt-loaded OMC and VC. This is attributed to the higher electronic conductivity (due to the thicker and more crystalline walls, seen by both X-ray diffraction and thermogravimetric analysis) and facilitated mass transport in the larger pores of the CIC support.
Dustin Banham, Fangxia Feng, Tobias Fürstenhaupt, Katie Pei, Siyu Ye, Viola Birss, Journal of Power Sources 196 (2011) 5438–5445

A2159 – Multi-wall carbon nanotube networks as potential resistive gas sensors for organic vapor detection

The sensitivity of multi-wall carbon nanotube (MWCNT) networks of randomly entangled pure nanotubes and those oxidized with acidic KMnO4 to various organic solvent vapors (iso-pentane, diethyl ether, acetone and methanol) has been investigated by resistance measurements. The solvents had different polarities given by Hansen solubility parameters and different volume fractions of saturated vapors defined by the vapor pressure. The results show that the network electrical resistance increases when exposed to organic solvent vapors, and a reversible reaction is observed when the network is removed from the vapors. The reaction with KMnO4 increases oxygen content on the nanotube surface and causes lower porosity of MWCNT network as well as higher electrical resistance, which improves the network selectivity to polar solvents. The investigated MWCNT networks could be potentially used as sensing elements for sensitive and selective organic vapor switches
P. Slobodian, P. Riha, A. Lengalova, P. Svoboda, P. Saha, Carbon 49 (2011) 2499-2507

A2157 – Heterogenization of [Ti(? 5-C 5HMe 4)Cl 3] on to MCM-41 and organomodified MCM-41 to form epoxidation catalyst

This paper describes the heterogenization of a tetramethylmonocyclopentadienyl titanium (IV) trichloride complex, [Ti(?5-C5HMe4)Cl3] onto mesoporous MCM-41. Its immobilization has been performed via a straightforward grafting process of the organometallic precursor in the pores of an MCM-41 host material and by reaction with previously organomodified MCM-41 material with a hydroxyl triazine based compound. Applying all-silica MCM-41 hosts, stable and heterogeneous liquid-phase epoxidation catalysts are obtained. Powder X-ray diffraction and nitrogen adsorption–desorption analysis indicated that the structural integrity of the support has been preserved during the titanium complex immobilization. These materials have been also extensively characterized using diffuse reflectance UV–vis, 13C and 28Si MAS NMR and FT-IR spectroscopy. With these techniques the strong adsorption of the intact catalytic complex within an all-silica MCM-41 host is demonstrated. These materials have been tested as catalyst for the epoxidation of aliphatic and aromatic alkenes with TBHP as oxidant exhibiting a significant selectivity toward the epoxide with negligible leaching of titanium species. The conversion values are moderated, being the olefin trend reactivity 1-octene > cyclohexene > styrene
Yolanda Pérez, Ruth Ballesteros, Mariano Fajardo, Isabel Sierra, Isabel del Hierro, Journal of Organometallic Chemistry 696 (2011) 1708-1715

A2156 – Ring opening of cis-decalin on bifunctional Ir/- and Pt/La-X zeolite catalysts

Zeolite La-X was loaded with iridium or platinum by ion exchange with cationic complexes of the noble metals, their thermal decomposition in air and reduction with hydrogen. The resulting bifunctional catalysts were used for the hydroconversion of cis-decalin in a high-pressure flow-type apparatus at temperatures between 200 and 255 °C and a hydrogen pressure of 5.2 MPa. Both Ir/La-X and Pt/La-X showed a high tendency for skeletal isomerization of decalin. An important isomer was formed by type A rearrangement, namely spiro[4.5]decane. For a safer peak assignment of the most desired products, the open-chain decanes, n-decane was catalytically isomerized, and the iso-decanes thereby generated were co-injected into the gas chromatograph with a liquid product from the hydroconversion of decalin. Open-chain decane yields of up to 12% were achieved. The molar carbon number distributions of the hydrocracked products were M-shaped indicating mainly C–C bond cleavage of the ring opening products with one remaining naphthenic ring via carbocations and the paring reaction.
Sandra Rabla, Andreas Haas, Dominic Santi, Cristina Flego, Marco Ferrari, Vincenzo Calemma, Jens Weitkamp, Applied Catalysis A: General 400 (2011) 131– 141

A2149 – Processing of low-density alumina foam

A novel method for synthesizing low-density alumina foam has been developed. The alumina foam with 98.5% porosity was synthesized by an unconventional route from an aqueous aluminum nitrate–sucrose solution. The resin formed by heating this solution underwent foaming and set into solid green foam, which was sintered at 1873 K. The thermogram of the green foam showed mass loss in four stages. The foam exhibited interconnected porous network with window size in the range 103–226 and 167–311 ?m for foams sintered at 1223 and 1873 K, respectively. The alumina foam sintered at 1223 K exhibited gamma phase and that sintered at 1873 K exhibited alpha phase.
Prasanta Jana, V. Ganesan, Journal of the European Ceramic Society 31 (2011) 75–78

A2148 – The production of a carbon-coated alumina foam

A method for producing ultra light carbon-coated alumina foam with a density of 0.04 g cm?3 and 99% porosity has been developed. It was synthesised from an aqueous aluminum nitrate–sucrose solution. The resin formed by heating this solution underwent foaming and set into solid green foam, which was sintered in the temperature range 1073–1873 K. The thermogram obtained by heating the green foam in argon showed 62 wt% mass loss occurring in three stages. The sintered foam constituted 81 wt% of ?-alumina in three-dimensional network and 19 wt% of carbon present as coating over the alumina framework. Phase analysis by X-ray diffraction revealed that carbon is in outer phase and ?-alumina is in the inner phase. Surface morphology of this foam, examined by scanning electron microscope showed open, fully interconnected and near spherical pores held together by hexagonal edges with a 300 ?m average pore size. Energy dispersive X-ray spectroscopy revealed peaks corresponding to carbon, oxygen and aluminum indicating that the foam is free from nitrogen impurity. The surface concentration of carbon is nearly 85 wt% while it coating thickness is about 10 ?m.
Prasanta Jana, V. Ganesan, Carbon 49 (2011) 3292-3298

A2138 – Adsorptive removal of Cu(II) and Ni(II) ions from aqueous media by chemical immobilization of three different aldehydes

The three aldehydes were chemically immobilized onto silica gel modified with 3-aminopropyltrimethoxy silane, just as the classic condensation reaction of Schiff bases. The obtained silica gel structures used as adsorbent were characterized by infrared spectroscopy, elemental analysis and thermogravimetric analysis. The adsorption capabilities of these adsorbents towards Cu(II) and Ni(II) from aqueous solutions were studied and values of adsorption were detected by an atomic absorption spectrometer. The maximum adsorption capacities and isotherm parameters were found from the Langmuir and Freundlich equations. The characteristics of Ni(II) and Cu(II) metal bindings were interpreted by using Scatchard plot graphics, and it was showed that in different concentrations multi-type and/or nonspecific interactions among metal ions and modified silica gel structures were the prevailing effects causing the Ni(II) and Cu(II) adsorptions. Conclusively, probable benefit of each specific binding type in adsorptions of Ni(II) and Cu(II) from aqueous media has been discussed in detail.
Hakan Dumrul, Ahmed Nuri Kursunlu, Ozcan Kocyigit, Ersin Guler, Seref Ertul, Desalination 271 (2011) 92–99

A2121 – Sulfonic-functionalized SBA-15 as an active catalyst for the gas-phase dehydration of Glycerol

Sulfonic-functionalized mesoporous silicas (SBA-15) were used as catalysts in the gas-phase dehydration of glycerol at moderate temperature (275 and 300 °C). For the tested conditions all the samples show a very high catalytic activity. At the lowest temperature and for 140 h on stream a nearly constant selectivity to acrolein of ca. 80% could be obtained. Both the pore size and density of acid sites play an important role in the deactivation rate and selectivity: larger pore size may extend significantly the catalytic activity and high density of acid sites may reduce acrolein production. Increasing the temperature to 300 °C is beneficial to the acrolein production, but it also leads to an increase of the deactivation rate.
João P. Lourenço, Maria I. Macedo, Auguste Fernandes, Catalysis Communications 19 (2012) 105–109

A2117 – Chemoselective crotonaldehyde hydrogen transfer reduction over pure and supported metal nitrates

A series of catalysts based on calcined aluminium, gallium, indium and zirconyl nitrates was synthesised. Gallium and zirconyl nitrate were also supported (impregnation method) over ZrO2 and TiO2. The whole set of catalysts was characterised and tested for the gas-phase chemoselective reduction of crotonaldehyde by hydrogen transfer from 2-propanol (Meerwein–Ponndorf–Verley process, MPV). Catalyst characterisation revealed that calcined nitrates consisted of metal oxides with residual metal nitrates as evidenced by FT-Raman and XPS measurements. Those systems showed high-strength acid sites (as determined by pyridine TPD). A relationship between high strength Brønsted plus Lewis acidity and the yield to 2-butenol was found for all the systems, calcined zirconyl nitrate being the solid leading to better catalytic results. Pyridine poisoning experiments confirmed the role of the strong acid sites in the MPV reduction of crotonaldehyde. However, all catalysts presented a severe deactivation process that seemed to consist of both irreversible and reversible processes since reactivation cycles only led to a partially recovered catalytic activity. The strong adsorption of polymeric species formed over the strong acid sites accounts for the irreversible deactivation process.
Juan F. Miñambres, Alberto Marinas, José M. Marinas, Francisco J. Urbano, Journal of Catalysis 295 (2012) 242–253

A2102 – Highly selective oxidation of alcohols using MnO2/TiO2-ZrO2 as a novel heterogeneous catalyst

MnO2/TiO2-ZrO2, which was synthesized by the adsorption method, demonstrated very high catalytic activity in the selective oxidation of benzyl alcohols to benzaldehydes with excellent yields and selectivity in short reaction times. The physical and chemical properties of MnO2/TiO2-ZrO2 were investigated by XRD, XRF, BET, FT-IR and SEM techniques. The influence of the catalyst support (SBA-15, ZSM-5, TiO2-ZrO2 and Y), type of metal oxide supported, method of loading and amount of manganese nitrate loading have been thoroughly investigated. Moreover, the catalyst has shown excellent reusability in the process
Ahmad Reza Massah, Roozbeh Javad Kalbasi, Mohammad Azadi, C. R. Chimie 15 (2012) 428–436

A2100 – Mesoporous materials for the removal of SO2 from gas streams

MCM-41 sorbent containing two metal oxides (CuO, CeO2) and an alkaline additive (LiCl) was prepared to remove SO2 from gas streams at 673 K. Two impregnation methods i.e. the template-ion exchange and the two solvents impregnation method were employed yielding a high dispersed state of the metal oxides inside the porosity of the MCM-41 sorbent. The MCM-41 sorbent was found to have a high adsorption capacity of 130 mg SO2/g at 673 K. During the adsorption process, cerium oxide partially oxidized SO2 into SO3 which was further chemically adsorbed on active sites (CuO, Li2O). The formation of CuSO4 and Li2SO4 was observed by X-ray diffraction after the reaction
Yannick Mathieu, Michel Soulard, Joël Patarin, Michel Molière, Fuel Processing Technology 99 (2012) 35–42

A2080 – Behaviors of NH4HSO4 in SCR of NO by NH3 over different cokes

Deposition of ammonium sulfates over catalysts is often observed during selective catalytic reduction (SCR) of NOX by NH3 in the presence of SO2 and H2O, especially at temperatures lower than 350 °C, which results in catalyst deactivation and equipment erosion. Activated coke was reported to be a support effective in reducing accumulation of ammonium sulfates on the catalyst surface. However, detailed information on stability of ammonium sulfates and the properties of coke affecting the stability have not been explored. This work studies decomposition behavior of NH4HSO4 deposited on different cokes in a TG-MS system. It shows that NH4HSO4 on coke decomposes in two steps: formation of NH3 and H2SO4 starting at about 170 °C and reduction of H2SO4 by coke to form SO2 at higher temperatures, regardless of the presence of NO. The decreased NH4HSO4 poisoning is attributed to reduction of H2SO4 because it frees the pores of coke. The BET surface area and pore volume of coke do not affect the reduction behavior of H2SO4 if only they are high enough; the oxygen and nitrogen containing functional groups in coke promote the reduction of H2SO4; the minerals in coke may interact with H2SO4 to form stable sulfates; V2O5 on coke and NO in the gas elevate the reduction temperature of H2SO4.
Pan Li, Qingya Liu, Zhenyu Liu, Chemical Engineering Journal 181– 182 (2012) 169– 173

A2079 – Partial oxidation of methane to syngas on bulk NiAl2O4 catalyst. Comparison with alumina supported nickel, platinum and rhodium catalysts

In this work the catalytic performance of NiAl2O4 catalyst in the partial oxidation of methane (CH4(1)/O2(0.5)/N2(8.5) and 4800 mL CH4 g?1 h?1) was investigated. This bulk catalyst resulted more active (70% conversion at 625 °C) than alumina supported nickel catalysts prepared by conventional impregnation (11%Ni/Al2O3-30% conversion at 625 °C and 14%Ni/Al2O3-65% conversion at 625 °C) and a commercial platinum catalyst (1%Pt/Al2O3-30% conversion at 625 °C). Further, the behaviour of NiAl2O4 was comparable to that of a commercial rhodium catalyst (1%Rh/Al2O3-75% conversion at 625 °C). Fresh and spent catalysts were characterised by N2-physisorption, H2-TPR, UV-vis-DRS, WDXRF, XRD, TGA-MS, TEM and Raman spectroscopy. After catalyst reduction CH4 conversion over bulk NiAl2O4 was associated with the formation of large amounts of metallic nickel crystallites with a relatively small size. Although significant coking was notice