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Fischer − tropsch synthesis using H2 / CO / CO2 syngas mixtures over a cobalt catalyst / Yali Yao in Industrial & engineering chemistry research, Vol. 49 N° 21 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 11061-11066 Titre : Fischer − tropsch synthesis using H2 / CO / CO2 syngas mixtures over a cobalt catalyst Type de document : texte imprimé Auteurs : Yali Yao, Auteur ; Diane Hildebrandt, Auteur ; David Glasser, Auteur Année de publication : 2011 Article en page(s) : pp. 11061-11066 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalyst  Synthesis  gas  Carbon  dioxide  Fischer  Tropsch  synthesis Résumé : The effect of CO2 on Fischer−Tropsch synthesis (FTS) on a cobalt based catalyst had been investigated in a fixed-bed microreactor. Two feed gases, H2:CO:CO2 = 2:1:0 and H2:CO:CO2 = 3:0:1, were mixed in various proportions thus varying the ratio of CO, CO2, and H2 stoichiometrically. The results show that CO and CO2 mixtures can be used as feed to a cobalt catalyst. Comparison of the FTS using different syngas mixtures (CO2/H2, CO2/CO/H2, and CO/H2) shows that: (1) CO2 can be hydrogenated along with CO in the FT reactor over cobalt catalyst, especially in the case of high content of CO2. (2) Hydrogenation of CO2 or CO/CO2 mixture leads to a typical Anderson−Schulz−Flory (ASF) distribution. These could support the hypothesis that CO2 hydrogenation processes might occur with the formation of CO as intermediate. (3) CO feed exhibit the typical two-alpha distribution while CO2 and CO2 rich feeds only exhibit a single-alpha distribution. This may also help us to understand the mechanisms that lead to product distributions in FT with single- and dual-alpha distributions. In spite of the fact that cobalt catalysts are not water−gas shift active, it is shown the rate of hydrocarbon production is maximized at an intermediate composition of the CO/CO2/H2 mixture. The results could have implications for the design of XTL (anything-to-liquids is a process that converts carbon and energy containing feedstock to high quality fuels and products, such as coal-to-liquids, biomass-to-liquids and gas-to-liquids) using cobalt catalysts in that it might be advantageous to keep some carbon dioxide in the syngas feed to the FTS process. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23448002 [article] Fischer − tropsch synthesis using H2 / CO / CO2 syngas mixtures over a cobalt catalyst [texte imprimé] / Yali Yao, Auteur ; Diane Hildebrandt, Auteur ; David Glasser, Auteur . - 2011 . - pp. 11061-11066. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 11061-11066 Mots-clés : Catalyst  Synthesis  gas  Carbon  dioxide  Fischer  Tropsch  synthesis Résumé : The effect of CO2 on Fischer−Tropsch synthesis (FTS) on a cobalt based catalyst had been investigated in a fixed-bed microreactor. Two feed gases, H2:CO:CO2 = 2:1:0 and H2:CO:CO2 = 3:0:1, were mixed in various proportions thus varying the ratio of CO, CO2, and H2 stoichiometrically. The results show that CO and CO2 mixtures can be used as feed to a cobalt catalyst. Comparison of the FTS using different syngas mixtures (CO2/H2, CO2/CO/H2, and CO/H2) shows that: (1) CO2 can be hydrogenated along with CO in the FT reactor over cobalt catalyst, especially in the case of high content of CO2. (2) Hydrogenation of CO2 or CO/CO2 mixture leads to a typical Anderson−Schulz−Flory (ASF) distribution. These could support the hypothesis that CO2 hydrogenation processes might occur with the formation of CO as intermediate. (3) CO feed exhibit the typical two-alpha distribution while CO2 and CO2 rich feeds only exhibit a single-alpha distribution. This may also help us to understand the mechanisms that lead to product distributions in FT with single- and dual-alpha distributions. In spite of the fact that cobalt catalysts are not water−gas shift active, it is shown the rate of hydrocarbon production is maximized at an intermediate composition of the CO/CO2/H2 mixture. The results could have implications for the design of XTL (anything-to-liquids is a process that converts carbon and energy containing feedstock to high quality fuels and products, such as coal-to-liquids, biomass-to-liquids and gas-to-liquids) using cobalt catalysts in that it might be advantageous to keep some carbon dioxide in the syngas feed to the FTS process. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23448002

Fischer – tropsch synthesis using H2 / CO / CO2 syngas mixtures over an iron catalyst / Yali Yao in Industrial & engineering chemistry research, Vol. 50 N° 19 (Octobre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 19 (Octobre 2011) . - pp. 11002-11012 Titre : Fischer – tropsch synthesis using H2 / CO / CO2 syngas mixtures over an iron catalyst Type de document : texte imprimé Auteurs : Yali Yao, Auteur ; Xinying Liu, Auteur ; Diane Hildebrandt, Auteur Année de publication : 2011 Article en page(s) : pp. 11002-11012 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Catalyst  Synthesis  gas  Carbon  dioxide  Fischer  Tropsch  synthesis Résumé : A series of low-temperature Fischer―Tropsch synthesis (FTS) experiments using a wide range of H2/CO/CO2 syngas mixtures have been performed to provide further insight into the effect of the CO2 on an iron-based catalyst during FTS. In comparison with CO hydrogenation, the reactivity for CO2 hydrogenation was lower and produced more CH4-rich short chain paraffins. Based on the correlation between the experimental results and the thermodynamic equilibrium calculations for the water gas shift (WGS) reaction, although the WGS reaction is far from the thermodynamic equilibrium under low-temperature FTS conditions, its equilibrium constraints determine the pathways and in particular whether CO is converted to CO2 or CO2 to CO. It is possible for CO2 to convert to hydrocarbons only when the composition of co-fed CO2 has a value higher than that set by the equilibrium constraints. A remarkable feature of our experimental results was that when the FTS system was not consuming but forming CO2, the reaction rates of both the FT and the WGS reactions were independent of the partial pressures of CO and CO2. Furthermore, with a decrease in the ratio of CO2/(CO+CO2) in the feed gas, it was observed that the hydrocarbon product formation rate reached a maximum and then maintained this value, even at a very high concentration of CO2 in the H2/CO/CO2 feed mixture. These results could justify the inclusion of CO2 in the syngas feed to the iron-based catalyst FTS processes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24573296 [article] Fischer – tropsch synthesis using H2 / CO / CO2 syngas mixtures over an iron catalyst [texte imprimé] / Yali Yao, Auteur ; Xinying Liu, Auteur ; Diane Hildebrandt, Auteur . - 2011 . - pp. 11002-11012. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 19 (Octobre 2011) . - pp. 11002-11012 Mots-clés : Catalyst  Synthesis  gas  Carbon  dioxide  Fischer  Tropsch  synthesis Résumé : A series of low-temperature Fischer―Tropsch synthesis (FTS) experiments using a wide range of H2/CO/CO2 syngas mixtures have been performed to provide further insight into the effect of the CO2 on an iron-based catalyst during FTS. In comparison with CO hydrogenation, the reactivity for CO2 hydrogenation was lower and produced more CH4-rich short chain paraffins. Based on the correlation between the experimental results and the thermodynamic equilibrium calculations for the water gas shift (WGS) reaction, although the WGS reaction is far from the thermodynamic equilibrium under low-temperature FTS conditions, its equilibrium constraints determine the pathways and in particular whether CO is converted to CO2 or CO2 to CO. It is possible for CO2 to convert to hydrocarbons only when the composition of co-fed CO2 has a value higher than that set by the equilibrium constraints. A remarkable feature of our experimental results was that when the FTS system was not consuming but forming CO2, the reaction rates of both the FT and the WGS reactions were independent of the partial pressures of CO and CO2. Furthermore, with a decrease in the ratio of CO2/(CO+CO2) in the feed gas, it was observed that the hydrocarbon product formation rate reached a maximum and then maintained this value, even at a very high concentration of CO2 in the H2/CO/CO2 feed mixture. These results could justify the inclusion of CO2 in the syngas feed to the iron-based catalyst FTS processes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24573296