HE0060 – Reprint of: CO2/CH4, CH4/H2 and CO2/CH4/H2 separations at high pressures using Mg2(dobdc)
High-pressure separations of binary and ternary mixtures of CO2, CH4, and H2 are relevant to carbon dioxide capture as well as hydrogen and natural gas purification. Metal–organic frameworks represent a class of porous materials that could be used to accomplish these separations, and Mg2(dobdc) (dobdc4? = 1,4-dioxido-2,5-benzenedicarboxylate), also sometimes referred to as Mg–MOF-74 or CPO-27–Mg, is an especially lightweight metal–organic framework with a high concentration of coordinatively-unsaturated metal sites decorating its interior surfaces. High pressure CH4 adsorption isotherms presented here, together with CO2 and H2 adsorption behavior, are analyzed using the Ideal Adsorbed Solution Theory to model CO2/CH4, CH4/H2, and CO2/CH4/H2 mixture separations using Mg2(dobdc). The selectivities, working capacities and breakthrough performances for these three mixtures are reported, and Mg2(dobdc) is shown to outperform zeolite 13X in each scenario.
HE0055 – Direct Synthesis of Amine-Functionalized MIL-101(Cr) Nanoparticles and Application to CO2 Capture
The synthesis of amine-functionalized metal-organic framework was obtained with chromic nitrate hydrate, 2-aminoterephthalic acid and and sodium hydroxide.. The adsorption isotherms of the probe gas CO2, N2 and CH4 (purity of 99.99) were measured using volumetric technique by an apparatus from SETARAM France (PCTpro-E&E). Before each measurement, the sample was evacuated at 150°C?? for 12 h. The adsorbed amounts ( Qi ) were calculated by the volumetric method. The ideal selectivity (?) of the sample was defined as: ? (A/B)= QA / QB , where QA is the adsorption uptake for gas A, and QB is the adsorption uptake for gas B.
HE0052 – Carbon monoliths for CO2 adsorption
In this article we present the characterization of some carbon monoliths, which have an open and permeable structure. Due to electrical and thermal conductivity of the carbon fibers these composites could be electrically desorbed. The monoliths were prepared from milled carbon fibers and a phenolic resin. The obtained monolithic composites were carbonized up to 650°C
and then the composites were steam activated at 800°C. By activation, the adsorption capacity of carbon dioxide was improved. The carbon fibers composites were characterized using scanning electron microscopy, atomic force microscopy, X-ray diffraction, BET surface area analysis and volumetric measurements of gas adsorption.
HE0050 – Metal Organic Frameworks as Adsorbents for Hydrogen Purification and Precombustion Carbon Dioxide Capture
Selected metal organic frameworks exhibiting representative properties—high surface area, structural flexibility, or the presence of open metal cation sites—were tested for utility in the separation of CO2 from H2 via pressure swing adsorption. Single-component CO2 and H2 adsorption isotherms were measured at 313 K and pressures up to 40 bar for Zn4O(BTB)2 (MOF-177, BTB3 = 1,3,5-benzenetribenzoate), Be12(OH)12(BTB)4 (Be-BTB), Co(BDP) (BDP2 = 1,4-benzenedipyrazolate), H3[(Cu4Cl)3(BTTri)8] (Cu-BTTri, BTTri3 = 1,3,5-enzenetristriazolate), and Mg2-(dobdc) (dobdc4 = 1,4-dioxido-2,5-benzenedicarboxylate). Ideal adsorbed solution theory was used to estimate realistic isotherms for the 80:20 and 60:40 H2/CO2 gas mixtures
relevant to H2 purification and precombustion CO2 capture, respectively. In the former case, the results afford CO2/H2 selectivities between 2 and 860 and mixed-gas working capacities,
assuming a 1 bar purge pressure, as high as 8.6 mol/kg and 7.4mol/L. In particular, metal organic frameworks with a high concentration of exposed metal cation sites, Mg2(dobdc) and
Cu-BTTri, offer significant improvements over commonly used adsorbents, indicating the promise of such materials for applications in CO2/H2 separations.
B3275 – Equimolar CO2 Absorption by Anion-Functionalized Ionic Liquids
Amino acid ionic liquid trihexyl(tetradecyl)phosphonium methioninate [P66614][Met] and prolinate [P66614][Pro] absorb CO2 in nearly 1:1 stoichiometry, surpassing by up to a factor of 2 the CO2 capture efficiency of previously reported ionic liquid and aqueous amine absorbants for CO2. Room temperature isotherms are obtained by barometric measurements in an accurately calibrated stirred cell, and the product identity is confirmed using in situ IR. Density functional theory (DFT) calculations support the 1:1 reaction stoichiometry and predict reaction enthalpies in good agreement with calorimetric measurements and isotherms
B3193 – Development of a Low Cost CO2 Capture System with a Novel Absorbent under the COCS Project
The COCS (Cost Saving CO2 Capture System) Project had been carried out by RITE in collaboration with four Japanese companies from April 2004 to March 2009. It was the R&D project to reduce CO2 capture cost by half compared to the cost of a conventional technology for CO2 removal from a blast furnace gas in an integrated steel works. One of the main research issues in this project was to develop a novel absorbent which could be regenerated with a low thermal energy. RITE especially led the development of new absorbents. Initially amine solvents were investigated through laboratory-scale experiments, and then some selected solvents were evaluated at the 1t-CO2/d test plant. RITE successfully developed innovative amine absorbents, which have high absorption rate and low desorption energy of about 2.5–2.65 GJ/t-CO2 for CO2 capture from a blast furnace gas.
B3079 – Amine-modified MCM-41 mesoporous silica for carbon dioxide capture
This paper presents an easy way to obtain a material with CO2 sorption properties by using commercially available MCM-41. In order to increase MCM-41 CO2 sorption capacity, 2.48 mmol g?1 of amine groups were anchored onto silica surface. A few carefully chosen spectroscopic techniques – namely infrared diffuse reflectance spectroscopy and solid-state 13C and 29Si nuclear magnetic resonance – demonstrated that amino groups are covalently bounded to mesoporous silica and not just adsorbed on it. CO2 uptake by the samples was investigated by microcalorimetry experiments performed at 30 °C. The amine functionalized material, MCM-41-NH2, exhibited a higher uptake of CO2 at very low pressures compared with the nongrafted material. The modified material presented heat of adsorption of ?98 versus ?32 kJ mol?1 for MCM-41 at low pressures. The mode of CO2 uptake in MCM-41-NH2 was both chemisorption at low pressures and physisorption at high pressures. Solid-state 13C nuclear magnetic resonance performed on amine-functionalized MCM-41 after CO2 adsorption experiments, showed a signal attributed to carbamate that was formed as a product of the reaction between CO2 and amine groups. This material has potential for CO2 recovery at low pressures/concentrations.
B3025 – Etude thermodynamique de solutions aqueuses d’amines démixantes pour le captage du dioxyde de carbone
Les alcanolamines en solution aqueuse sont les solvants chimiques les plus utilisés pour capter le CO2. Le captage du gaz par une amine combine dans ce cas des réactions chimiques réversibles et une dissolution physique du CO2. La séparation du CO2 de la solution absorbante est ensuite possible grâce au caractère réversible des réactions chimiques. Des démonstrateurs ont été développés afin d’évaluer les capacités de ce procédé. La monoéthanolamine (MEA) en raison de sa grande réactivité avec le CO2 a été le solvant chimique utilisé dans ces premiers essais sur pilotes industriels. Le coût de la régénération de ce solvant limite son utilisation à grande échelle. Dès lors, de nouvelles voies de captage dites en rupture ont été envisagées dans le but de réduire le coût de traitement du CO2. C’est dans cette optique que le projet ACACIA (Amélioration du Captage du CO2 Industriel et Anthropique), financé par le Fond Unique Interministériel (FUI) et le Grand Lyon, a été mis en place en 2008. Le procédé en rupture étudié au cours de ce travail consiste à utiliser des solvants démixants. Il s’agit de solutions aqueuses d’amines pouvant former deux phases liquides immiscibles à une température et une concentration en CO2 données
B3018 – Direct measurement of the heat of solution and solubility of carbon dioxide in 1-hexyl-3-methylimidazolium bis[trifluoromethylsulfonyl]amide and 1-octyl-3-methylimidazolium bis[trifluoromethylsulfonyl]amide
We report the first direct experimental determination of the enthalpies of solution of carbon dioxide in ionic liquids 1-hexyl-3-methylimidazolium bis[trifluoromethylsulfonyl]amide ([C6mim][NTf2]) and 1-octyl-3-methylimidazolium bis[trifluoromethylsulfonyl]amide ([C8mim][NTf2]) at 313.15 K and pressures up to 5 MPa. The experiments are based on the detection of heat of mixing of gas with ionic liquid using a flow calorimetric technique. For both ionic liquids, gas solubilities were derived from experimental calorimetric data and were compared with solubility data obtained by a newly designed high-pressure solubility measurement apparatus. Results of enthalpies of solution were compared to enthalpies derived from Henry’s law constant, available in literature. The analysis of the data reported herein confirms the consistency between the direct determination of the heats of solution and their derivation from precise
enough solubility data. Also it was proven that, within the experimental uncertainty, it is possible to derive reliable solubility data from the calorimetric experiments.
B2892 – Measurement and Modeling of Enthalpy of Solution of Carbon Dioxide in Aqueous Solutions of Diethanolamine at Temperatures of (322.5 and 372.9) K and Pressures up to 3 Mpa
The enthalpies of solution (?solH) of carbon dioxide (CO2) in two aqueous solutions (w = 0.1500 and w = 0.3000) of diethanolamine (DEA) have been measured at two temperatures ((322.5 and 372.9) K) and pressures up to 3 MPa. Measurements were carried out by a flow calorimetric technique using a custom-made flow-mixing unit combined with a SETARAM C-80 isothermal differential heat-flux calorimeter. Enthalpies of solution of CO2 (?solH) have been obtained as function of loading, ? (moles CO2/mol amine). Influences of temperature, pressure, and absorbent composition have been discussed. Solubility data of the gas into the different absorbent (s) were derived from the enthalpic data. The experimental enthalpies of solution (?solH) of carbon dioxide (CO2) in the two aqueous solutions of diethanolamine have been compared with data derived from a rigorous thermodynamic model of phase equilibria based on a ?- approach. Interaction parameters were chosen to be adjustable parameters in this model and were fitted to vapor-liquid equilibrium data. Several formulations for the amine protonation and carbamate formation equilibrium constants have been tested. The different contributions to the enthalpy of solution of CO2 in aqueous solutions of DEA have been analyzed.
B2774 – Measurement of Heat of CO2 Absorption into 2-Amino-2-methyl-1-propanol (AMP)/Piperazine (PZ) Blends Using Differential Reaction Calorimeter
In this work, a Differential Reaction Calorimeter (DRC) was used to measure differential heats of CO2 absorption into aqueous solutions of 2-amino-2-methyl-1-propanol (AMP) + piperazine (PZ) blend. The measurement was carried out at 40, 60, and 80oC, and at CO2 loading ranging from nil to CO2 saturation. The AMP/PZ molar ratios of 2:1, 4:1, and 6:1 were tested. Effects of reaction temperature, CO2 loading, and molar ratio were analyzed according to reaction mechanism.
B2587 – Flow calorimetric insight to competitive sorption of carbon dioxide and methane on coal
Flow calorimetric technique was used to obtain information on the additional adsorption of carbon dioxide on two samples of Czech bituminous coal with pre-adsorbed methane. It was found that most of the adsorption sites for CO2 remain unoccupied when the coal surface is saturated by pre-adsorbed methane. The calorimetric measurements then confirmed the displacement ability of carbon dioxide to methane molecules pre-adsorbed on the coal.
B2571 – Enthalpy of Solution of Carbon Dioxide in Aqueous Solutions of Monoethanolamine at Temperatures of 322.5 K and 372.9 K and Pressures up to 5 MPa
The enthalpies of solution (?solH) of carbon dioxide (CO2) in two aqueous solutions (w = 0.1500 and w = 0.3000) of monoethanolamine (MEA) have been measured at two temperatures (322.5 K and 372.9 K) and pressures up to 5 MPa. Measurements were carried out by a flow calorimetric technique using a custom-made flow-mixing unit combined with a SETARAM
C-80 isothermal differential heat-flux calorimeter. Enthalpies of solution of CO2 (?solH) have been obtained as function of loading R (moles CO2/mol amine). Solubility data of the gas into the different absorbent (s) were derived from the enthalpic data.
B2478 – Enthalpies of absorption and solubility of carbon dioxide in aqueous polyamine solutions
The enthalpies of absorption and solubility at T=298.15 K of carbon dioxide in aqueous solutions of bis-(3-dimethylaminopropyl)amine (CAS RN: [6711-48-4]) are reported in this paper. It was observed that the saturation loading of the CO2 is a=2.9 mol CO2/mol TMBPA, which is close to the theoretical value, a0=3 mol CO2/mol TMBPA. The molar heat of absorption of CO2 is independent of the polyamine concentration of the solutions and the amount of CO2 absorbed and was calculated to be ?absHm= – 44 (±2) kJ mol-1 CO2.
B2371 – Use of calorimetric techniques for the investigation of CO2 capture and storage
Capture and storage demonstration projects are multiplying worldwide as industrial companies are facing the obligation to cut back their CO2 emissions. As a consequence, industrial interest is generating important technological developments at the process level, but another significant aspect is the drive to find and understand the chemistries and technologies that will provide the most efficient capture and
the safest storage in the field. Most CCS technologies are based upon gas-solid or gas-liquid adsorption or absorption systems and during such a process, heat is exchanged by the system. By measuring this heat, the corresponding thermal data can provide critical information on the amount of adsorbed (absorbed) CO2 at a given temperature and gas pressure and also on the kinetics of the reaction. Such a measurement is ideally performed using the calorimetric technique. This paper explains how such a calorimetric technique is used for the investigation
of gas-liquid absorption for CO2 capture using frequently used amine solutions and for CO2 storage in saline aquifers
B2295 – Development of novel tertiary amine absorbents for CO2 capture
Development of high performance CO2 absorbents to reduce the regeneration energy cost to almost half the current cost. To achieve this target, 25 tertiary amine based CO2 sorbents with different chemical structures are investigated. Solvent selection procedures were carried out based on their CO2 absorption rate, loading capacity and heat of recation measurements using the DRC calorimetric technique.
B2026 – Enthalpy and solubility data of CO2 in water and NaCl(aq) at conditions of interest for geological sequestration
The transfer of acid gases in saline aquifers under high pressures is an important step in their geological storage. The dissolution of carbon
dioxide in water and in aqueous solution of sodium chloride was studied by measuring the heat of mixing ?Hmix of a supercritical gas with the
liquid phase. The measurements were carried out using a new customized mixing unit developed for an isothermal differential heat flux calorimeter
Setaram BT 2.15D. The experimental technique was specifically adapted for measurements with acid gases (H2S, CO2) in water and salt solutions.
The heats of mixing were measured at temperatures of 323.1-373.1 K, and at pressures up to 20MPa in the regions where the solution is unsaturated
and saturated by gas. The concentration dependence of ?Hmix allowed to derive simultaneously the limiting enthalpy of solution ?Hsol and the gas
solubility limit. The influence of temperature, pressure and salt concentration (up to 3 molal) on the solubility limits and on the enthalpies of solution
was examined. The salting out effect, as measured by Setchenov constant, does not vary strongly with the temperature, pressure, or electrolyte
concentration. The consistency between our results and literature data was verified. The reasonable agreement suggests that this technique, beside
being a reliable source of enthalpy data, is also suitable for the indirect determination of gas solubility limits.
B1279 – Use of flow calorimetry for determining enthalpies of absorption and the solubility of CO2 in aqueous monoethanolamine solutions
A flow mixing unit adapted to a Setaram C-80 calorimeter was used for measuring enthalpies of absorption of carbon dioxide in a 30 wt % aqueous solution of monoethanolamine (MEA) at three temperatures (313.15, 353.15, and 393.15 K) and three pressures (2.0, 5.0, and 10.0 MPa). Determinations were performed both in the region where the gas is fully absorbed in the solvent and also in the region of concentrations above the saturation. Experimental data served to obtain the integral enthalpies of absorption and for indirect determination of solubility limits. Where comparison was possible, the presented results derived from calorimetric determinations were in reasonable agreement with those obtained from phase equilibria measurements.
B1144 – Enthalpies of absorption and solubility of CO2 in aqueous solutions of methyldiethanolamine.
A flow mixing unit using a SETARAM C-80 calorimeter, developed for measuring the enthalpy of solution of two fluids, has been used to measure enthalpies of absorption of carbon dioxide in a 30 wt.% aqueous solution of methyldiethanolamine (MDEA) at three temperatures 313.15, 353.15, 393.15 K and three pressures 2.0, 5.0, 10.0 MPa. We have established that the effect measured by calorimetry corresponds not only to the absorption of CO2 in the aqueous solution but also to the vaporisation of water into the carbon dioxide depending on the temperature and the pressure of the experiment. The enthalpies measured by calorimetry were compared with those calculated from solubility measurements and a reasonable agreement within the accuracy of measurement and calculation was found.
A2173 – Amine modified mesocellular siliceous foam (MCF) as a sorbent for CO2
Adsorption is considered a promising method for carbon capture. CO2 adsorbents take a variety of forms – but one approach is to fill mesoporous substrates with a polymeric CO2 selective sorbent. SBA-15 and mesocellular siliceous foam (MCF) are high pore volume, high surface area ordered mesoporous materials for which modification with amine should result in high capacity, highly selective adsorbents. SBA-15 and MCF were separately loaded with approximately one pore volume equivalent of linear polyethyleneimine (PEI) (Mw = 2500) or branched PEI (Mn = 1200). CO2 adsorption/desorption isotherms under dry CO2 were obtained at 75, 105 and 115 °C. The CO2 adsorption/desorption kinetics were improved with temperature, though the CO2 capacities generally decreased. The adsorption capacity for MCF loaded with branched PEI at 105 and 115 °C were 151 and 133 mg/g adsorbent, respectively (in 50% CO2/Ar, 20 min adsorption time). These are significantly higher than the adsorption capacity observed for SBA-15 loaded with branched PEI under same conditions, which were 107 and 83 mg/g adsorbent, respectively. Thus the results indicate that, on a unit mass basis, amine modified MCF's are potentially better adsorbents than amine modified SBA-15 for CO2 capture at modestly elevated temperature in a vacuum swing adsorption process.
A2166 – Spinel mixed oxides as oxygen carriers for chemical looping combustion
Several transition metal based mixed oxides with the spinel structure have been prepared, characterised and tested using a TGA apparatus simulating the oxidation and reduction periods in CLC. Despite the fact that gas phase diffusion limitations have been encountered under our TGA test conditions, the spinel materials were compared in terms of oxygen transfer capacity as well as oxidation and reduction rates. The best working spinel formulation is Cu0.95Fe1.05AlO4, with high oxygen transfer capacity, high oxidation rate, but a relatively low reduction rate compared to our reference formulation (60%NiO-40%NiAl2O4).
Impregnating NiO on the former spinel material allowed to increase both oxygen transfer capacity and reactivity of the resulting materials. While oxidation rates in the same order of magnitude to that of the reference material could be obtained, the maximum measured reduction rate was still only slightly above half that of the reference material.
A1995 – CO2 and H2O reduction by solar thermochemical looping using SnO2/SnO redox reactions: Thermogravimetric analysis
The thermochemical dissociation of CO2 and H2O from reactive SnO nanopowders is studied via thermogravimetry analysis. SnO is first produced by solar thermal dissociation of SnO2 using concentrated solar radiation as the high-temperature energy source. The process targets the production of CO and H2 in separate reactions using SnO as the oxygen carrier and the syngas can be further processed to various synthetic liquid fuels. The global process thus converts and upgrades H2O and captured CO2 feedstock into solar chemical fuels from high-temperature solar heat only, since the intermediate oxide is not consumed but recycled in the overall process. The objective of the study was the kinetic characterization of the H2O and CO2 reduction reactions using reactive SnO nanopowders synthesized in a high-temperature solar chemical reactor. SnO conversion up to 88% was measured during H2O reduction at 973 K and an activation energy of 51 ± 7 kJ/mol was identified in the temperature range of 798-923 K. Regarding CO2 reduction, a higher temperature was required to reach similar SnO conversion (88% at 1073 K) and the activation energy was found to be 88 ± 7 kJ/mol in the range of 973-1173 K with a CO2 reaction order of 0.96. The SnO conversion and the reaction rate were improved when increasing the temperature or the reacting gas mole fraction. Using active SnO nanopowders thus allowed for efficient and rapid fuel production kinetics from H2O and CO2.
A1994 – CO2 splitting by thermo-chemical looping based on ZrxCe1 xO2 oxygen carriers for synthetic fuel generation
The thermochemical CO2 splitting via cerium-based mixed oxides is considered. This process targets the recycling and upgrading of CO2 emissions for the production of solar fuels. The CO2 reduction is achieved by thermochemical looping using ceria–zirconia solid solutions as oxygen carriers: (1) the mixed oxide is first reduced by thermal activation for releasing some oxygen from its lattice, (2) the reduced oxide is then oxidized with CO2 for producing carbon monoxide and the initial metal oxide that is recycled to the first step. Reactive cerium-based mixed oxides were first synthesized as nanopowders by different soft chemical routes. Their reactivity was then investigated experimentally by thermogravimetry analysis to demonstrate that the produced nanoparticles react efficiently with CO2. The two-step process consisting of thermal activation and CO2-splitting reaction was able to produce CO repeatedly. The influence of
the synthesis method, the Zr content in ZrxCe1 xO2, and the temperature of the CO2 reduction reaction was investigated. The material was reduced at 1400 C in flowing Ar and the CO2 reduction was performed below this temperature (typically in the range of 700–1200 C). Both the CO production and the material cyclability were improved when decreasing the Zr content, although the reduction extent was lessened. The Ce0.75Zr0.25O2 and Ce0.9Zr0.1O2 redox catalysts withstood repeated cycles without any noticeable sintering and reactivity losses. The most reactive material was the powder synthesized via the Pechini method (242 lmol CO/g at 1000 C).
A1993 – Effect of H2O on Mg(OH)2 carbonation pathways for combined CO2 capture and storage
Mg-bearing sorbents, derived from silicate minerals and industrial wastes, can act as combined carbon capture and storage media in various energy conversion systems. Mg(OH)2 carbonation in the slurry phase occurs spontaneously and recent results show improved gas–solid carbonation with comparable materials in the presence of H2O vapor; however, the reaction mechanism is still poorly understood at high temperature and pressure conditions. This study investigated the pathways of H2O enhanced Mg(OH)2 carbonation at elevated temperatures and CO2 pressures (up to 673 K and 1.52 MPa) in the presence of steam and in the slurry phase. For a given reaction temperature, carbonation conversion showed dramatic increase with increasing H2O loading. Comprehensive solid analyses via thermogravimetric analysis, X-ray diffraction, and UV-Raman allowed for qualitative and quantitative compositional characterization of reacted solids. The results suggest that a hydrated environment facilitates the formation of intermediate hydrated magnesium carbonate species. The hydrated carbonates form relatively quickly and can transform into anhydrous carbonates while subjected to greater H2O loading, higher temperature, and/or longer reaction time.
A1830 – Valorisation of spent coffee grounds as CO2 adsorbents for postcombustion capture applications
In this work spent coffee grounds from single-use capsules were used as the starting material for producing low-cost activated carbons. The activation conditions were selected and optimised to produce microporous carbons with high CO2 adsorption capacity and selectivity, thus with potential to be used as adsorbents in postcombustion CO2 capture applications. Two activation methods are compared: physical activation with CO2 and chemical activation with KOH. The first method is considered less contaminant; however, leads to carbons with lower textural development and thus lower CO2 adsorption capacity than those obtained by activation with KOH. On the other hand, multicomponent adsorption cyclic experiments pointed out that the CO2/N2 selectivity of physically activated carbons is higher than that of chemically activated carbons.
A1727 – Fast CO2 sequestration by aerogel composites
The increasingly evident impact of anthropogenic CO2 emissions on climate change and associated environmental effects is stimulating the search for viable methods to remove this gas. One of the most promising strategies is the long-term storage of CO2 in inert, insoluble and thermodynamically-stable materials. This strategy mimics the natural reactions that transform silicates into carbonates regulating the cycle of CO2 on the surface of the Earth, operating on a geological time-scale. Consequently, the aim is to accelerate these reactions to be applicable on
the timescale of human lives. We present the various technologies developed or proposed to date, based on this particular approach. The principal limiting factor is that high pressures and temperatures are required to produce appropriate materials capable of CO2 sequestration and storage. Nevertheless, the synthetic materials known as aerogels can be modified in shape, size and chemical functionality so as to catalyse the process of CO2 elimination through silicates (of Ca or Mg), considerably reducing the reaction time and working at atmospheric pressure and temperature.
A1724 – Microporous phenol–formaldehyde resin-based adsorbents for pre-combustion CO2 capture
Different types of phenolic resins were used as precursor materials to prepare adsorbents for the separation of CO2 in pre-combustion processes. In order to obtain highly microporous carbons with suitable characteristics for the separation of CO2 and H2 under high pressure conditions, phenol–formaldehyde resins were synthesised under different conditions. Resol resins were obtained by using an alkaline environment while Novolac resins were synthesised in the presence of acid catalysts. In addition, two organic additives, ethylene glycol (E) and polyethylene glycol (PE) were included in the synthesis. The phenolic resins thus prepared were carbonised at different temperatures and then physically activated with CO2. The carbons produced were characterised in terms of texture, chemical composition and surface chemistry. Maximum CO2 adsorption capacities at atmospheric pressure were determined in a thermogravimetric analyser. Values of up to 10.8 wt.% were achieved. The high-pressure adsorption of CO2 at room temperature was determined in a high-pressure magnetic suspension balance. The carbons tested showed enhanced CO2 uptakes at high pressures (up to 44.7 wt.% at 25 bar). In addition, it was confirmed that capture capacities depend highly on the microporosity of the samples, the narrow micropores (pore widths of less than 0.7 nm) being the most active in CO2 adsorption at atmospheric pressure. The results presented in this work suggest that phenol–formaldehyde resin-derived activated carbons, particularly those prepared with the addition of ethylene glycol, show great potential as adsorbents for pre-combustion CO2 capture.
A1715 – Reactivity of CO2 traps in aerogel–wollastonite composites
Synthetic wollastonite has been used as the active phase embedded into two different silica aerogel composites. These composites are different in respect of the route used for the synthesis of the wollastonite powder. Texture and composition of both types of composite have been characterized. In addition, several factors (pH, reaction time, CO2 saturation, etc.) that could help to optimize the carbonation process at room temperature and pressure have been studied. Under the same conditions, both composites confirm previous results showing efficiencies as
CO2 sequesters between 80% and 100% in only 15 min of gas flow. The textural characteristics of the aerogel, together with the grain size of the synthetic wollastonite powder, not only increase the speed of the reaction, but also inhibit the appearance of a passivating layer on the surface of the wollastonite grains attacked by the CO2. This is an outstanding feature as it insists on a cutting-edge challenge of the CO2 research: its economical availability.
A1537 – Improvements of Calcium Oxide Based Sorbents for multiple CO2 Capture cycles
This study presents the development of a novel calcium-oxide sorbent for carbon dioxide capture. In this work, CaO sorbent was impregnated with different molar percentage of titanium ethoxide. The sorbent prepared with 50 % of titanium ethoxide resulted in the best uptake characteristics for CO2. Compared to others, a higher BET surface area and a larger pore volume were observed. An excellent stability during extended carbonationdecarbonation cycles was also demonstrated. The high titanium content limits the sintering of particles and thus stabilizes the microstructure of CaO.
A1507 – Study of inexpensive oxygen carriers for chemical looping combustion
Norwegian industrial tailings and by-products, as well as naturally occurring minerals and ores have been surveyed with the purpose of identifying candidate oxygen carrier materials for use in a chemical looping combustion process. Nine materials, based on manganese and/or iron oxide, were selected for an initial screening test; six were deemed promising and were hence investigated further. Thermogravimetric experiments were performed to investigate the oxygen capacity, the reaction kinetics and reversibility of the oxygen absorption reaction. A manganese ore with a reversible capacity of 4.9 wt% oxygen at 1000 °C was selected as the most promising for chemical looping combustion applications. This material was modified by addition of calcia to explore the possibility of enhancing the kinetic, catalytic and mechanical properties. The addition of excess calcium relative to manganese resulted in formation of calcium manganite and related phases. The oxygen capacity of the modified material was 4.5 wt% at 1000 °C, but it has potential advantages in terms of kinetics and chemical and mechanical stability relative to the pure ore.
A1470 – Application of thermogravimetric analysis to the evaluation of aminated solid sorbents for CO2 capture
In this work a series of solid sorbents were synthesized by immobilizing liquid amines on the surface of a mesoporous alumina. The samples were chemically characterized and BET surface areas calculated from the N2 adsorption isotherms at 77 K. The CO2 capture performance of the sorbents and their thermal stability was studied by thermogravimetric methods. The effect of amine loading on the CO2 capture performance of the prepared sorbents was also evaluated. Analysis of TG-DTG curves showed that thermal stabilization of the amines is significantly improved by immobilizing them on an inorganic support. Temperature-programmed CO2 adsorption tests from 298 K up to 373 K at atmospheric pressure, proved to be a useful technique for assessing the capacity of sorbents for CO2 capture. Alumina impregnated with diethylenetriamine presented the highest CO2 adsorption capacities throughout the tested temperature range.
A1461 – Mesoporous micelle templated silica with incorporated C8 and C18 phase
Mesoporous silica material of MCM-41 type was synthesized by co-condensation of highly concentrated octyltriethoxysilane (OTEOS), octadecyltriethoxysilane (ODTEOS) and tetraethoxysilane (TEOS). The obtained hybrid materials were characterized using XRD, TG-DSC and low temperature adsorption/desorption of nitrogen. It was shown that the applied method of synthesis allows to obtain silica of MCM-41 type with a high degree of hydrocarbon saturation
A1448 – Multicyclic study on the carbonation of CaO using different limestones
Different samples of limestones, with small differences in their stoichiometry, have been studied comparatively. The carbonation reaction has been studied for a large area of isothermal temperatures. The conditions for the multicyclic experiments of calcination/carbonation were: isothermal temperature 670°C, heating time 60 min and carrier gas CO2. The final carbonation
conversion depends mainly on the isothermal temperature of the carbonation reaction and the heating time. The final temperature of the calcination reaction depends on the percentage of CaO that it has not been conversed to CaCO3 in the repeated carbonation experiments. The quantity of CaO that has not been carbonated, in the same sample, affects the values of the coefficients of the kinetic model that fit the calcination reaction. In the multicyclic experiments the carbonation conversion for two of the four studied samples, was high enough in comparison to other samples of calcite. At sample A the reduction of the carbonation conversion during the first five cycles is less than it is at other samples from the literature. Under the above experimental conditions – isothermal temperature and heating time – specific samples consisted mainly of calcite can absorb larger quantities of CO2 than samples consisted mainly of dolomite.
A1410 – CO2 and SO2 uptake by oil shale ashes. Effect of pre-treatment on kinetics
In the present research, CO2 and SO2 binding ability of different oil shale ashes and the effect of pretreatment (grinding, preceding calcination) of these ashes on their binding properties and kinetics was studied using thermogravimetric, SEM, X-ray, and energy dispersive X-ray analysis methods. It was shown that at 700 °C, 0.03–0.28 mmol of CO2 or 0.16–0.47 mmol of SO2 was bound by 100 mg of ash in 30 min. Pre-treatment conditions influenced remarkably binding parameters. Grinding decreased CO2 binding capacities, but enhanced SO2 binding in the case of fluidized bed ashes. Grinding of pulverized firing ashes increased binding parameters with both gases. Calcination at higher temperatures decreased binding parameters of both types of ashes with both gases studied. Clarification of this phenomenon was given. Kinetic analysis of the binding process was carried out, mechanism of the reactions and respective kinetic con-
stants were determined. It was shown that the binding process with both gases was controlled by diffusion. Activation energies in the temperature interval of 500–700 °C for CO2 binding with circulating fluidized bed combustion ashes were in the range of 48–82 kJ mol-1, for SO2 binding 43–107 kJ mol-1. The effect of pre-treatment on the kinetic parameters was estimated.
A1394 – Effects of Carbon on the Rates of Reduction in Iron-based Chemical Looping
The availability and low cost of coal and natural gas make them favorable fuels for energy conversion processes. However, the combustion of carbon-based fuels inevitably results in production of CO2. To avert climate change and comply with likely future regulations, the CO2 byproduct must be efficiently captured. Unfortunately, existing carbon capture methods result in up to a 2-fold increase in capital and operating costs. Chemical looping technologies are a group of processes that can separate the CO2 stream in-situ by utilizing iron oxide composite particles as oxygen carriers. The process allows for efficient total carbon capture, therefore ensuring a sustainable future for carbon-fueled hydrogen production. The objective of this study was to explore the effect the presence of carbon has on the reduction rates of 11 iron oxide-based particle compositions. The 11 particles have been isolated from previous recyclability tests of 126 different particle compositions. Faster reduction rates allows for a reduction in capital costs in scale-up design and a smaller oxygen carrier requirement, both of which are required to ensure the success of CDCL. The experiments use TGA to determine the rate of reduction at 900°C and 1 atmosphere in a methane (CH4) environment. T-7, T-2 and T-3 compositions have
the fastest rate of reduction. The addition of CeO2 and ZrO2 based promoters are shown to enhance these rates even more and reduce the rate of carbon deposition. The use of
promoters needs to be explored more extensively to find the optimal composition for an acceptable trade-off in cost for performance.
A1388 – Carbon dioxide sequestration in municipal solid waste incinerator (MSWI) bottom ash
During bottom ash weathering, carbonation under atmospheric conditions induces physico-chemical evolutions leading to the pacification of the material. Fresh bottom ash samples were subjected to an accelerated carbonation using pure CO2. The aim of this work was to quantify the volume of CO2 that could be sequestrated with a view to reduce greenhouse gas emissions and investigate the possibility of upgrading some specific properties of the material with accelerated carbonation. Carbonation was performed by putting 4 mm-sieved samples in a CO2
chamber. The CO2 pressure and the humidity of the samples were varied to optimize the reaction parameters. Unsieved material was also tested. Calcite formation resulting from accelerated carbonation was investigated by thermogravimetry and differential scanning calorimetry (TG/DSC) and metal leaching tests were performed. The volume of sequestrated CO2 was on average 12.5 L/kg dry matter (DM) for unsieved material and 24 L/kg DM for 4 mm-sieved samples. An ash humidity of 15% appeared to give the best results. The reaction was drastically
accelerated at high pressure but it did not increase the volume of sequestrated CO2. Accelerated carbonation, like the natural phenomenon, reduces the dangerous nature of the material. It decreases the pH from 11.8 to 8.2 and causes Pb, Cr and Cd leaching to decrease. This process could reduce incinerator CO2 emissions by 0.5–1%.
A1380 – Behavior of Different Calcium-Based Sorbents in a Calcination/Carbonation Cycle for CO2 Capture
The aim of this work is to identify the characteristics of natural carbonates which upon calcination generate an optimum material for use as a CO2-capturing sorbent in large-scale industrial CO2-producing sources. Nine different naturally occurring Ca/Mg carbonates were selected for this study. The carbonates were fully characterized by a variety of analytical techniques including atomic absorption and redox volumetry, for the chemical characterization of the carbonates, and optical and scanning electron microscopy (SEM), X-ray
diffraction, and Fourier transform infrared spectroscopy, to determine their crystallinity, morphology, and the presence of impurities. They were then subjected to successive (up to 100) calcination/recarbonation cycles, and their conversion decay curves were interpreted on the basis of the physical and chemical characteristics of the parent carbonates. The textural development of the sorbents during cycling was studied by Hg porosimetry and SEM. Hardness tests were also conducted on selected samples. It was concluded that both carbonate
purity and crystallinity are important parameters in determining the performance of the sorbents. The activity of all the sorbents tested turned out to be highly dependent on the pore structure of the calcines and their variation during cycling. In turn, the natural tendency of the sorbents to develop low surface areas (poor efficiencies) during cycling seems to be enhanced by the presence of moderate amounts of Mg.
A1379 – Ammoxidation of carbon materials for CO2 capture
Ammoxidised carbons were produced from three different starting materials: an activated carbon obtained from wood by chemical activation using the phosphoric acid process, a steam activated peatbased carbon, and a char obtained from a lowcost biomass feedstock, olive stones. Nitrogen was successfully incorporated into the carbon matrix of the different materials, the amount of nitrogen uptake being proportional to the oxygen content of the precursor. At room temperature the CO2 capture capacity of the samples was found to be related to the narrow micropore volume, while at 100 ?C other factors such as surface basicity took on more relevance. At 100 ?C all the ammoxidised samples presented an enhancement in CO2 uptake compared to the parent carbons.
A1378 – Development of low-cost biomass-based adsorbents for postcombustion CO2 capture
In this work a series of carbon adsorbents were prepared from a low-cost biomass residue, olive stones. Two different approaches were studied: activation with CO2 and heat treatment with gaseous ammonia. The results showed that both methods are suitable for the production of adsorbents with a high CO2 adsorption capacity, and their potential application in VSA or TSA systems for postcombustion CO2 capture. It was found that the presence of nitrogen functionalities enhances CO2 adsorption capacity, especially at low partial pressures.
A1377 – CO2 capture by adsorption with nitrogen enriched carbons
The success of CO2 capture with solid sorbents is dependent on the development of a low cost sorbent with high CO2 selectivity and adsorption capacity. Immobilised amines are expected to offer the benefits of liquid amines in the typical absorption process, with the added advantages that solids are easy to handle and that they do not give rise to corrosion problems. In this work, different alkylamines were evaluated as a potential source of basic sites for CO2 capture, and a commercial activated carbon was used as a preliminary support in order to study the effect of the impregnation. The amine coating increased the basicity and nitrogen content of the carbon. However, it drastically reduced the microporous volume of the activated carbon, which is chiefly responsible for CO2 physisorption, thus decreasing the capacity of raw carbon at room temperature.
A1376 – Surface modification of activated carbons for CO2 capture
The reduction of anthropogenic CO2 emissions to address the consequences of climate change is a matter of concern for all developed countries. In the short term, one of the most viable options for reducing carbon emissions is to capture and store CO2 at large stationary sources. Adsorption with solid sorbents is one of the most promising options. In this work, two series of materials were prepared from two commercial activated carbons, C and R, by heat treatment with gaseous ammonia at temperatures in the 200–800 8C range. The aim was to improve the selectivity and capacity of the sorbents to capture CO2, by introducing basic nitrogen-functionalities into the carbons. The sorbents were characterised in terms of texture and chemical composition. Their surface chemistry was studied through temperature programmed desorption tests and X-ray photoelectron spectroscopy. The capture performance of the
carbons was evaluated by using a thermogravimetric analyser to record mass uptakes by the samples when exposed to a CO2 atmosphere.
A1374 – Hybrid Mesoporous Materials for Carbon Dioxide Separation
One common method for CO2 separation from mixed gas streams is by absorption in aqueous solutions of alkanolamines4, for example monoethanolamine (MEA) or diethanolamine (DEA). It is widely accepted that CO2 becomes absorbed via the formation of both carbamates and bicarbonates.In this study, solid phase hexagonal mesoporous silicas (HMS) of known porosity (pore diameter) were modified using aminopropyltrimethoxysilane and related compounds to provide very high surface area materials with varied concentrations of surface bound amine and
hydroxyl functional groups
A1368 – Synthesis and characterization of bimetallic Fe/Mn oxides for chemical looping combustion
Fe-Mn mixed oxides have been prepared by different routes, characterized, and tested with TGA for application as oxygen carriers in the CLC process. These mixed oxides exhibit a lower oxygen transfer capacity than Ni based materials which is also dependant on synthesis method. In-situ XRD analysis was performed with one sample and allowed to clearly demonstrate the reaction pathway, reduction and oxidation reactions occurring stepwise, with little phase coexistence. SEM-EDS analysis on reduced and re-oxidized samples show atom migration occurs on a rather long distance, forming Fe0 and MnO particles during reduction which are oxidized back to (Fe,Mn)2O3.
A1367 – A mechanistic investigation of a calcium-based oxygen carrier for chemical looping combustion
Chemical looping combustion (CLC) has been suggested as an energy-efficient method for the capture of carbon dioxide from combustion. It is indirect combustion by the use of an oxygen carrier, which can be used for CO2 capture in power-generating processes. The possibility of CLC using a calcium-based oxygen carrier is investigated in this paper. In the air reactor air is supplied to oxidize CaS to CaSO4, where oxygen is transferred from air to the oxygen carrier; the reduction of CaSO4 to CaS takes place in the fuel reactor. The exit gas from the fuel reactor is CO2 and H2O. After condensation of water, almost pure CO2 could be obtained. The thermodynamic and kinetic problem of the reduction reactions of CaSO4 with CO and H2 and the oxidization reactions of CaS with O2 is discussed in the paper to investigate the technique possibility. To prevent SO2 release from the process of chemical looping combustion using a calcium-based oxygen carrier, thermochemical CaSO4 reduction and CaS oxidation are discussed. Thermal simulation experiments are carried out using a thermogravimetric analyzer (TGA). The properties of the products are characterized by Fourier transform infrared (FT-IR) spectroscopy and X-ray diffractometry (XRD), and the optimal reaction parameters are evaluated. The effects of reaction temperature, reductive gas mixture, and oxygen partial pressure on the composition of flue gas are discussed. The suitable temperature of the air reactor is between 1050 and 1150 ?C and the optimal temperature of the fuel reactor between 900 and 950 ?C
A1366 – Semi-continuous operation of chemical-looping combustion with metal oxides supported on bentonite in an annular fluidized bed reactor
The chemical-looping combustion (CLC) process has an advantage of no energy loss for CO2 separation without NOx formation. This process consists of oxidation and reduction reactors where metal oxides particles are circulating through these two reactors. Nickel oxide supported on bentonite was selected based on their good reactivity, and semi-continuous operation was conducted in an annular fluidized bed reactor. The reaction efficiency is determined by analyzing concentrations of CO and H2 in flue gas and their concentrations are below 10 % at the optimum operating conditions.
A1351 – Application of thermogravimetric analysis to the evaluation of aminated solid sorbents for CO2 capture
In this work a series of solid sorbents were synthesized by immobilizing liquid amines on the surface of a mesoporous alumina. The
samples were chemically characterized and BET surface areas calculated from the N2 adsorption isotherms at 77 K. The CO2 capture
performance of the sorbents and their thermal stability was studied by thermogravimetric methods. The effect of amine loading
on the CO2 capture performance of the prepared sorbents was also evaluated. Analysis of TG-DTG curves showed that thermal stabilization
of the amines is significantly improved by immobilizing them on an inorganic support. Temperature-programmed CO2
adsorption tests from 298 K up to 373 K at atmospheric pressure, proved to be a useful technique for assessing the capacity of
sorbents for CO2 capture. Alumina impregnated with diethylenetriamine presented the highest CO2 adsorption capacities throughout
the tested temperature range.
A0874 – Design, synthesis and characterization of mixed matrix material for CO2 capture
A0787 – Carbon dioxide sequestration in municipal solid waste incinerator (MSWI) bottom ash
During bottom ash weathering, carbonation under atmospheric conditions induces physico-chemical evolutions leading to the pacification
of the material. Fresh bottom ash samples were subjected to an accelerated carbonation using pure CO2. The aim of this work was to quantify
the volume of CO2 that could be sequestrated with a view to reduce greenhouse gas emissions and investigate the possibility of upgrading
some specific properties of the material with accelerated carbonation. Carbonation was performed by putting 4 mm-sieved samples in a CO2
chamber. The CO2 pressure and the humidity of the samples were varied to optimize the reaction parameters. Unsieved material was also
tested. Calcite formation resulting from accelerated carbonation was investigated by thermogravimetry and differential scanning calorimetry
(TG/DSC) and metal leaching tests were performed. The volume of sequestrated CO2 was on average 12.5 L/kg dry matter (DM) for unsieved
material and 24 L/kg DM for 4 mm-sieved samples. An ash humidity of 15% appeared to give the best results. The reaction was drastically
accelerated at high pressure but it did not increase the volume of sequestrated CO2. Accelerated carbonation, like the natural phenomenon,
reduces the dangerous nature of the material. It decreases the pH from 11.8 to 8.2 and causes Pb, Cr and Cd leaching to decrease. This process
could reduce incinerator CO2 emissions by 0.5-1%.
A0494 – The effects of procedural variables on the maximum capture efficiency of CO2 using a carbonation/calcination cycle of carbonate rocks
The effect of procedural variables-mass and heating and cooling rate-on the maximum capture efficiency of CO2 is studied, using a carbonation/calcination cycle, for a series of carbonation rocks with different stoichiometries of dolomite and calcite. The extent of carbonation and the cyclability depends particularly on dolomite presence and at the same time seems to be influenced by the existence of impurities. Samples having the highest percentage of calcite and the lowest percentage of impurities seemed to be independent on the above variables. In limestone samples with small quantity of dolomite, impurities or a combination of both of them was observed a very small increase in the extent of carbonation due to the increase in the initial mass of the samples, while these samples in the case of the same initial mass presented an increase in the extent of carbonation due to the decrease in the cooling and the second heating rate.