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Investigation of the Enhanced Water Gas Shift Reaction Using Natural and Synthetic Sorbents for the Capture of CO2 / Christoph R. Müller in Industrial & engineering chemistry research, Vol. 48 N° 23 (Décembre 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 23 (Décembre 2009) . - pp. 10284–10291 Titre : Investigation of the Enhanced Water Gas Shift Reaction Using Natural and Synthetic Sorbents for the Capture of CO2 Type de document : texte imprimé Auteurs : Christoph R. Müller, Auteur ; Roberta Pacciani, Auteur ; Christopher D. Bohn, Auteur Année de publication : 2010 Article en page(s) : pp. 10284–10291 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Investigation--Enhanced--Water  Gas--Shift  Reaction--Using  Natural--Synthetic  Sorbents--Capture--CO2 Résumé : The water gas shift (WGS) reaction was conducted in the presence of two natural and two synthetic CaO-based sorbents. It was shown that such sorbents can affect the WGS in two ways: (i) by catalysis of the reaction and (ii) by altering the equilibrium position by abstraction of CO2 from the gas phase. It was shown that CaO can significantly enhance the production of H2 during the WGS reaction; however, a trade-off between the production of H2 and contamination of the product gas with CO2 (the “CO2 slip”) has to be made. It was found that CaO catalyzes the WGS reaction. The carbonation reaction was very close to thermodynamic equilibrium, even at small contact times at 650 °C. However, the concentration of H2 was significantly below that predicted from equilibrium considerations. In our experiments, once the sorbent had been fully carbonated, it was regenerated by heating to release the CO2 so that it could be reused. In such a cyclic experiment, calcium magnesium acetate, a synthetic sorbent, was the best sorbent tested, albeit only over five cycles of reaction, with respect to the amount of H2 produced. The other sorbents, especially limestone, revealed a decrease in the production of hydrogen with the number of cycles. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900772q [article] Investigation of the Enhanced Water Gas Shift Reaction Using Natural and Synthetic Sorbents for the Capture of CO2 [texte imprimé] / Christoph R. Müller, Auteur ; Roberta Pacciani, Auteur ; Christopher D. Bohn, Auteur . - 2010 . - pp. 10284–10291. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 23 (Décembre 2009) . - pp. 10284–10291 Mots-clés : Investigation--Enhanced--Water  Gas--Shift  Reaction--Using  Natural--Synthetic  Sorbents--Capture--CO2 Résumé : The water gas shift (WGS) reaction was conducted in the presence of two natural and two synthetic CaO-based sorbents. It was shown that such sorbents can affect the WGS in two ways: (i) by catalysis of the reaction and (ii) by altering the equilibrium position by abstraction of CO2 from the gas phase. It was shown that CaO can significantly enhance the production of H2 during the WGS reaction; however, a trade-off between the production of H2 and contamination of the product gas with CO2 (the “CO2 slip”) has to be made. It was found that CaO catalyzes the WGS reaction. The carbonation reaction was very close to thermodynamic equilibrium, even at small contact times at 650 °C. However, the concentration of H2 was significantly below that predicted from equilibrium considerations. In our experiments, once the sorbent had been fully carbonated, it was regenerated by heating to release the CO2 so that it could be reused. In such a cyclic experiment, calcium magnesium acetate, a synthetic sorbent, was the best sorbent tested, albeit only over five cycles of reaction, with respect to the amount of H2 produced. The other sorbents, especially limestone, revealed a decrease in the production of hydrogen with the number of cycles. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900772q

Laser diagnostic investigation of the bubble eruption patterns in the freeboard of fluidized beds. 1. optimization of acetone planar laser induced fluorescence measurements / Georg Hartung in Industrial & engineering chemistry research, Vol. 47 n°15 (Août 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5686–5697 Titre : Laser diagnostic investigation of the bubble eruption patterns in the freeboard of fluidized beds. 1. optimization of acetone planar laser induced fluorescence measurements Type de document : texte imprimé Auteurs : Georg Hartung, Auteur ; Christoph R. Müller, Auteur ; Johan Hult, Auteur ; John S. Dennis, Auteur Année de publication : 2008 Article en page(s) : p. 5686–5697 Note générale : Bibliogr. p. 5696-5697 Langues : Anglais (eng) Mots-clés : Freeboard  gas  --  mixing;  Acetone  PLIF;  Bubble  eruption  pattern Résumé : Here, the mixing of the freeboard gas with the gas of single bubbles and a continuous stream of bubbles is investigated using acetone planar laser induced fluorescence (PLIF), a technique only recently introduced to fluidized bed research [Solimene et al. Chem. Eng. Sci.2007, 62, 94]. Various improvements with respect to laser diagnostics are presented leading to optimal signals from acetone PLIF. The results obtained are compared with models presented in the literature. The observed bubble eruption pattern generally corresponds to the models proposed by Levy and Lockwood [ AIChE J.1983, 29, 889], Yórquez-Ramirez and Duursma [ Powder Technol.2001, 116, 76], and Solimene et al. [ Chem. Eng. Sci.2007, 62, 94]. No difference was observed between the eruption patterns of a single bubble compared to a continuous stream of bubbles. In contrast to the models of Yórquez-Ramirez and Duursma and Solimene et al., five different patterns of the release of gas at a dome formed by a rising bubble are observed. An explanation for the formation of a thin layer of acetone after the eruption of a bubbles is given. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0713543 [article] Laser diagnostic investigation of the bubble eruption patterns in the freeboard of fluidized beds. 1. optimization of acetone planar laser induced fluorescence measurements [texte imprimé] / Georg Hartung, Auteur ; Christoph R. Müller, Auteur ; Johan Hult, Auteur ; John S. Dennis, Auteur . - 2008 . - p. 5686–5697. Bibliogr. p. 5696-5697 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5686–5697 Mots-clés : Freeboard  gas  --  mixing;  Acetone  PLIF;  Bubble  eruption  pattern Résumé : Here, the mixing of the freeboard gas with the gas of single bubbles and a continuous stream of bubbles is investigated using acetone planar laser induced fluorescence (PLIF), a technique only recently introduced to fluidized bed research [Solimene et al. Chem. Eng. Sci.2007, 62, 94]. Various improvements with respect to laser diagnostics are presented leading to optimal signals from acetone PLIF. The results obtained are compared with models presented in the literature. The observed bubble eruption pattern generally corresponds to the models proposed by Levy and Lockwood [ AIChE J.1983, 29, 889], Yórquez-Ramirez and Duursma [ Powder Technol.2001, 116, 76], and Solimene et al. [ Chem. Eng. Sci.2007, 62, 94]. No difference was observed between the eruption patterns of a single bubble compared to a continuous stream of bubbles. In contrast to the models of Yórquez-Ramirez and Duursma and Solimene et al., five different patterns of the release of gas at a dome formed by a rising bubble are observed. An explanation for the formation of a thin layer of acetone after the eruption of a bubbles is given. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie0713543

Performance of a novel synthetic Ca-based solid sorbent suitable for desulfurizing flue gases in a fluidized bed / Roberta Pacciani in Industrial & engineering chemistry research, Vol. 48 N° 15 (Août 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7016–7024 Titre : Performance of a novel synthetic Ca-based solid sorbent suitable for desulfurizing flue gases in a fluidized bed Type de document : texte imprimé Auteurs : Roberta Pacciani, Auteur ; Christoph R. Müller, Auteur ; John F. Davidson, Auteur Année de publication : 2009 Article en page(s) : pp. 7016–7024 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Dolomite  Limestone  Carbonation  Sulfation Résumé : The extent and mechanism of sulfation and carbonation of limestone, dolomite, and chalk, were compared with a novel, synthetic sorbent (85 wt % CaO and 15 wt % Ca12Al14O33), by means of experiments undertaken in a small, electrically heated fluidized bed. The sorbent particles were used either (i) untreated, sieved to two particle sizes and reacted with two different concentrations of SO2, or (ii) after being cycled 20 times between carbonation, in 15 vol % CO2 in N2, and calcination, in pure N2, at 750 °C. The uptake of untreated limestone and dolomite was generally low (<0.2 gSO2/gsorbent), confirming previous results. However, the untreated chalk and the synthetic sorbent were found to be substantially more reactive with SO2, and their final uptake was significantly higher (>0.5 gSO2/gsorbent) and essentially independent of the particle size. Here, comparisons are made on the basis of the sorbents in the calcined state. Hg-intrusion porosimetry, performed on calcined sorbents, revealed that the pore volume of limestone and dolomite was distributed almost entirely across small pores, which were easily plugged and hindered the diffusion of SO2 through the particle; this was confirmed by EDS analysis. Conversely, the pore size distribution of calcined chalk and fresh synthetic sorbent revealed the presence of pore volume also in the macroporous region; these bigger pores were not prematurely blocked by the newly formed CaSO4 and therefore allowed sulfation to proceed uniformly throughout the particle. It was also found that the uptake of SO2 by limestone, dolomite, and chalk was substantially lower when the particles had been subjected to cycles of calcination and carbonation in CO2 prior to sulfation; this was attributed to the loss in pore volume in the small pores with cycles of carbonation and calcination, as confirmed by Hg-intrusion porosimetry. The uptake of the synthetic sorbent, on the other hand, was much closer to that achieved when the sorbent was used untreated, because its pore volume in large pores was not lost with cycling. The capacities for the uptake of SO2, on a basis of unit mass of calcined sorbent, were comparable for the chalk and the synthetic sorbent. However, previous work has demonstrated the ability of the synthetic sorbent to retain its capacity for CO2 over many cycles of carbonation and calcination: much more so than natural sorbents such as chalk and limestone. Accordingly, the advantage of the synthetic sorbent is that it could be used to remove CO2 from flue gases and, at the end of its life, to remove SO2 on a once-through basis. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900181y [article] Performance of a novel synthetic Ca-based solid sorbent suitable for desulfurizing flue gases in a fluidized bed [texte imprimé] / Roberta Pacciani, Auteur ; Christoph R. Müller, Auteur ; John F. Davidson, Auteur . - 2009 . - pp. 7016–7024. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 15 (Août 2009) . - pp. 7016–7024 Mots-clés : Dolomite  Limestone  Carbonation  Sulfation Résumé : The extent and mechanism of sulfation and carbonation of limestone, dolomite, and chalk, were compared with a novel, synthetic sorbent (85 wt % CaO and 15 wt % Ca12Al14O33), by means of experiments undertaken in a small, electrically heated fluidized bed. The sorbent particles were used either (i) untreated, sieved to two particle sizes and reacted with two different concentrations of SO2, or (ii) after being cycled 20 times between carbonation, in 15 vol % CO2 in N2, and calcination, in pure N2, at 750 °C. The uptake of untreated limestone and dolomite was generally low (<0.2 gSO2/gsorbent), confirming previous results. However, the untreated chalk and the synthetic sorbent were found to be substantially more reactive with SO2, and their final uptake was significantly higher (>0.5 gSO2/gsorbent) and essentially independent of the particle size. Here, comparisons are made on the basis of the sorbents in the calcined state. Hg-intrusion porosimetry, performed on calcined sorbents, revealed that the pore volume of limestone and dolomite was distributed almost entirely across small pores, which were easily plugged and hindered the diffusion of SO2 through the particle; this was confirmed by EDS analysis. Conversely, the pore size distribution of calcined chalk and fresh synthetic sorbent revealed the presence of pore volume also in the macroporous region; these bigger pores were not prematurely blocked by the newly formed CaSO4 and therefore allowed sulfation to proceed uniformly throughout the particle. It was also found that the uptake of SO2 by limestone, dolomite, and chalk was substantially lower when the particles had been subjected to cycles of calcination and carbonation in CO2 prior to sulfation; this was attributed to the loss in pore volume in the small pores with cycles of carbonation and calcination, as confirmed by Hg-intrusion porosimetry. The uptake of the synthetic sorbent, on the other hand, was much closer to that achieved when the sorbent was used untreated, because its pore volume in large pores was not lost with cycling. The capacities for the uptake of SO2, on a basis of unit mass of calcined sorbent, were comparable for the chalk and the synthetic sorbent. However, previous work has demonstrated the ability of the synthetic sorbent to retain its capacity for CO2 over many cycles of carbonation and calcination: much more so than natural sorbents such as chalk and limestone. Accordingly, the advantage of the synthetic sorbent is that it could be used to remove CO2 from flue gases and, at the end of its life, to remove SO2 on a once-through basis. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie900181y

Production of very pure hydrogen with simultaneous capture of carbon dioxide using the redox reactions of iron oxides in packed beds / Christopher D. Bohn in Industrial & engineering chemistry research, Vol. 47 N°20 (Octobre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7623-7630 Titre : Production of very pure hydrogen with simultaneous capture of carbon dioxide using the redox reactions of iron oxides in packed beds Type de document : texte imprimé Auteurs : Christopher D. Bohn, Editeur scientifique ; Christoph R. Müller, Editeur scientifique ; Jason P. Cleeton, Editeur scientifique Année de publication : 2008 Article en page(s) : P. 7623-7630 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Hydrogen  Carbon  dioxide  Oxides  H2  CO2 Résumé : A chemical looping process, which uses a packed bed of the various oxides of iron, has been formulated to produce separate, pure streams of H2 and CO2 from syngas. The process has the following stages: (1) Reduction of Fe2O3 to Fe0.947O in the syngas from gasifying coal or biomass. This stage generates pure CO2, once the water has been condensed. (2) Subsequent oxidation of Fe0.947O to Fe3O4 using steam, to simultaneously produce H2. (3) Further oxidation of Fe3O4 to Fe2O3 using air to return the oxide to step 1. Step 1 was studied here using a mixture of CO + CO2 + N2 as the feed to a packed bed of iron oxide particles, while measuring the concentrations of CO and CO2 in the off-gas; step 2 was investigated by passing steam in N2 through the packed bed and measuring the quantity of H2 produced. The third step simply involved passing air through the bed. Reduction to Fe, rather than Fe0.947O, in step 1 gave low levels of H2 in step 2 after 10 cycles of reduction and oxidation and led to the deposition of carbon at lower temperature. Step 3, i.e. reoxidizing the particles in air to Fe2O3, led to no deterioration of the hydrogen yield in step 2 and benefited the process by (i) increasing the heat produced in each redox cycle and (ii) preventing the slip of CO from the bed in step 1. The proposed process is exothermic overall and very usefully generates separate streams of very pure H2 and CO2 without complicated separation units. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800335j [article] Production of very pure hydrogen with simultaneous capture of carbon dioxide using the redox reactions of iron oxides in packed beds [texte imprimé] / Christopher D. Bohn, Editeur scientifique ; Christoph R. Müller, Editeur scientifique ; Jason P. Cleeton, Editeur scientifique . - 2008 . - P. 7623-7630. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N°20 (Octobre 2008) . - P. 7623-7630 Mots-clés : Hydrogen  Carbon  dioxide  Oxides  H2  CO2 Résumé : A chemical looping process, which uses a packed bed of the various oxides of iron, has been formulated to produce separate, pure streams of H2 and CO2 from syngas. The process has the following stages: (1) Reduction of Fe2O3 to Fe0.947O in the syngas from gasifying coal or biomass. This stage generates pure CO2, once the water has been condensed. (2) Subsequent oxidation of Fe0.947O to Fe3O4 using steam, to simultaneously produce H2. (3) Further oxidation of Fe3O4 to Fe2O3 using air to return the oxide to step 1. Step 1 was studied here using a mixture of CO + CO2 + N2 as the feed to a packed bed of iron oxide particles, while measuring the concentrations of CO and CO2 in the off-gas; step 2 was investigated by passing steam in N2 through the packed bed and measuring the quantity of H2 produced. The third step simply involved passing air through the bed. Reduction to Fe, rather than Fe0.947O, in step 1 gave low levels of H2 in step 2 after 10 cycles of reduction and oxidation and led to the deposition of carbon at lower temperature. Step 3, i.e. reoxidizing the particles in air to Fe2O3, led to no deterioration of the hydrogen yield in step 2 and benefited the process by (i) increasing the heat produced in each redox cycle and (ii) preventing the slip of CO from the bed in step 1. The proposed process is exothermic overall and very usefully generates separate streams of very pure H2 and CO2 without complicated separation units. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800335j