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Catalytic carbon dioxide reforming of methane to synthesis gas over activated carbon catalyst / Qilei Song in Industrial & engineering chemistry research, Vol. 47 N° 13 (Juillet 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4349–4357 Titre : Catalytic carbon dioxide reforming of methane to synthesis gas over activated carbon catalyst Type de document : texte imprimé Auteurs : Qilei Song, Auteur ; Rui Xiao, Auteur ; Yanbing Li, Auteur ; Laihong Shen, Auteur Année de publication : 2008 Article en page(s) : p. 4349–4357 Note générale : Bibliogr. p. 4357 Langues : Anglais (eng) Mots-clés : Methane;  Catalytic  activity;  Kinetics Résumé : The catalytic activity and kinetic behavior of catalytic reforming of methane with carbon dioxide over activated carbon were investigated as a function of reaction temperature, gas hourly space velocity (GHSV), and partial pressures of CH4 and CO2. The CH4 and CO2 conversions were greatly influenced by the reaction temperature in the range of 850−1050 °C. The apparent activation energies for CH4 and CO2 consumption and CO and H2 production were 32.63 ± 1.06, 25.54 ± 1.79, 24.81 ± 3.06, and 32.99 ± 2.58 kcal/mol, respectively. The curves of reaction rates versus GHSV showed various trends at different temperatures and indicated 7500 mL/h·g-cat was sufficient for operation in the kinetic regime. The reaction rate of methane and carbon dioxide over activated carbon was affected significantly by the partial pressures. Under a higher CO2 pressure, the excess CO2 reacted with H2 through the reverse water−gas shift (RWGS) reaction. The predictions of the CH4 and CO2 reaction rates based on a semiexperimental formula fitted satisfactorily with the experiments data. The results of mass balance, BET, XRD, and SEM studies in the deactivation test indicated that the catalyst deactivation was mainly attributed to the carbon deposition and might be alleviated at high temperatures. On the basis of the experimental results and Langmuir−Hinshelwood mechanism in the literature, a reaction mechanism was proposed. The overall reaction pathway involves the adsorption and cracking of methane and CO2 adsorption and gasification with carbon cracked. The RWGS reaction occurs simultaneously. Overall, a derived semitheoretical kinetic equation satisfactorily predicted the experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800117a [article] Catalytic carbon dioxide reforming of methane to synthesis gas over activated carbon catalyst [texte imprimé] / Qilei Song, Auteur ; Rui Xiao, Auteur ; Yanbing Li, Auteur ; Laihong Shen, Auteur . - 2008 . - p. 4349–4357. Bibliogr. p. 4357 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N° 13 (Juillet 2008) . - p. 4349–4357 Mots-clés : Methane;  Catalytic  activity;  Kinetics Résumé : The catalytic activity and kinetic behavior of catalytic reforming of methane with carbon dioxide over activated carbon were investigated as a function of reaction temperature, gas hourly space velocity (GHSV), and partial pressures of CH4 and CO2. The CH4 and CO2 conversions were greatly influenced by the reaction temperature in the range of 850−1050 °C. The apparent activation energies for CH4 and CO2 consumption and CO and H2 production were 32.63 ± 1.06, 25.54 ± 1.79, 24.81 ± 3.06, and 32.99 ± 2.58 kcal/mol, respectively. The curves of reaction rates versus GHSV showed various trends at different temperatures and indicated 7500 mL/h·g-cat was sufficient for operation in the kinetic regime. The reaction rate of methane and carbon dioxide over activated carbon was affected significantly by the partial pressures. Under a higher CO2 pressure, the excess CO2 reacted with H2 through the reverse water−gas shift (RWGS) reaction. The predictions of the CH4 and CO2 reaction rates based on a semiexperimental formula fitted satisfactorily with the experiments data. The results of mass balance, BET, XRD, and SEM studies in the deactivation test indicated that the catalyst deactivation was mainly attributed to the carbon deposition and might be alleviated at high temperatures. On the basis of the experimental results and Langmuir−Hinshelwood mechanism in the literature, a reaction mechanism was proposed. The overall reaction pathway involves the adsorption and cracking of methane and CO2 adsorption and gasification with carbon cracked. The RWGS reaction occurs simultaneously. Overall, a derived semitheoretical kinetic equation satisfactorily predicted the experimental results. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800117a

Effect of Temperature on Reduction of CaSO4 Oxygen Carrier in Chemical-Looping Combustion of Simulated Coal Gas in a Fluidized Bed Reactor / Oilei Song in Industrial & engineering chemistry research, Vol. 47 n°21 (Novembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8148–8159 Titre : Effect of Temperature on Reduction of CaSO4 Oxygen Carrier in Chemical-Looping Combustion of Simulated Coal Gas in a Fluidized Bed Reactor Type de document : texte imprimé Auteurs : Oilei Song, Auteur ; Rui Xiao, Auteur ; Zhongyi Deng, Auteur Année de publication : 2008 Article en page(s) : p. 8148–8159 Note générale : chemical engineering Langues : Anglais (eng) Mots-clés : Chemical-looping  combustion Résumé : Chemical-looping combustion (CLC) is a promising combustion technology for gaseous and solid fuel with efficient use of energy and inherent separation of CO2. The concept of a coal-fueled CLC system using calcium sulfate (CaSO4) as oxygen carrier is proposed in this study. Reduction tests of CaSO4 oxygen carrier with simulated coal gas were performed in a laboratory-scale fluidized bed reactor in the temperature range of 890−950 °C. A high concentration of CO2 was obtained at the initial reduction period. CaSO4 oxygen carrier exhibited high reactivity initially and decreased gradually at the late period of reduction. The sulfur release during the reduction of CaSO4 as oxygen carrier was also observed and analyzed. H2 and CO conversions were greatly influenced by reduction temperature. The carbon deposition ratio was found to be quite low. The oxygen carrier conversion and mass-based reaction rates during the reduction at typical temperatures were compared. Higher temperatures would enhance reaction rates and result in high conversion of oxygen carrier. An XRD patterns study indicated that CaS was the dominant product of reduction and the variation of relative intensity with temperature is in agreement with the solid conversion. The slight content of CaO in reduced oxygen carrier at high temperatures was due to the formation of SO2 and H2S during the reduction period. ESEM analysis indicated that the surface structure of oxygen carrier particles changed significantly from impervious to porous after reduction. Slight agglomeration of small grains occurred for reduced particles at 950 °C. EDS analysis also demonstrated the transfer of oxygen from the oxygen carrier to the fuel gas and a certain amount of sulfur loss and CaO formation on the surface at higher temperatures. The reduction kinetics of CaSO4 oxygen carrier was explored with the shrinking unreacted-core model. The apparent kinetic parameters were obtained, and the kinetic equation well predicted the experimental data. Finally, some basic considerations on the use of CaSO4 oxygen carrier in a CLC system for solid fuels were discussed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8007264 [article] Effect of Temperature on Reduction of CaSO4 Oxygen Carrier in Chemical-Looping Combustion of Simulated Coal Gas in a Fluidized Bed Reactor [texte imprimé] / Oilei Song, Auteur ; Rui Xiao, Auteur ; Zhongyi Deng, Auteur . - 2008 . - p. 8148–8159. chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°21 (Novembre 2008) . - p. 8148–8159 Mots-clés : Chemical-looping  combustion Résumé : Chemical-looping combustion (CLC) is a promising combustion technology for gaseous and solid fuel with efficient use of energy and inherent separation of CO2. The concept of a coal-fueled CLC system using calcium sulfate (CaSO4) as oxygen carrier is proposed in this study. Reduction tests of CaSO4 oxygen carrier with simulated coal gas were performed in a laboratory-scale fluidized bed reactor in the temperature range of 890−950 °C. A high concentration of CO2 was obtained at the initial reduction period. CaSO4 oxygen carrier exhibited high reactivity initially and decreased gradually at the late period of reduction. The sulfur release during the reduction of CaSO4 as oxygen carrier was also observed and analyzed. H2 and CO conversions were greatly influenced by reduction temperature. The carbon deposition ratio was found to be quite low. The oxygen carrier conversion and mass-based reaction rates during the reduction at typical temperatures were compared. Higher temperatures would enhance reaction rates and result in high conversion of oxygen carrier. An XRD patterns study indicated that CaS was the dominant product of reduction and the variation of relative intensity with temperature is in agreement with the solid conversion. The slight content of CaO in reduced oxygen carrier at high temperatures was due to the formation of SO2 and H2S during the reduction period. ESEM analysis indicated that the surface structure of oxygen carrier particles changed significantly from impervious to porous after reduction. Slight agglomeration of small grains occurred for reduced particles at 950 °C. EDS analysis also demonstrated the transfer of oxygen from the oxygen carrier to the fuel gas and a certain amount of sulfur loss and CaO formation on the surface at higher temperatures. The reduction kinetics of CaSO4 oxygen carrier was explored with the shrinking unreacted-core model. The apparent kinetic parameters were obtained, and the kinetic equation well predicted the experimental data. Finally, some basic considerations on the use of CaSO4 oxygen carrier in a CLC system for solid fuels were discussed. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8007264