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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

Making sense of the fischer − tropsch synthesis reaction / Xiaojun Lu in Industrial & engineering chemistry research, Vol. 49 N° 20 (Octobre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 20 (Octobre 2010) . - pp. 9753–9758 Titre : Making sense of the fischer − tropsch synthesis reaction : Start - up Type de document : texte imprimé Auteurs : Xiaojun Lu, Auteur ; Diane Hildebrandt, Auteur ; Xinying Liu, Auteur Année de publication : 2011 Article en page(s) : pp. 9753–9758 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Fischer  tropsch  reaction Résumé : Conventional Fischer−Tropsch experiments were conducted to investigate the early stages (start-up) of the reaction of a TiO2-supported cobalt catalyst in a continuous stirred tank reactor and compared to the later stages. Thus, both short-term and long-term experiments were performed starting with fresh catalysts in each case. The experimental results showed that stirrer speed had an influence on the Fischer−Tropsch performance only in the short term. This suggested that under typical reaction conditions in a gas−solid system, long-term the Fischer−Tropsch reaction is not controlled by external mass transfer. After between about 30 and 80 h (depending on the temperature), large changes in reaction rate and product selectivity were observed, and these time-on-stream experiments showed that these changes were caused neither by the reaction conditions nor by the external mass transfer. Two possible explanations are proposed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1011933 [article] Making sense of the fischer − tropsch synthesis reaction : Start - up [texte imprimé] / Xiaojun Lu, Auteur ; Diane Hildebrandt, Auteur ; Xinying Liu, Auteur . - 2011 . - pp. 9753–9758. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 20 (Octobre 2010) . - pp. 9753–9758 Mots-clés : Fischer  tropsch  reaction Résumé : Conventional Fischer−Tropsch experiments were conducted to investigate the early stages (start-up) of the reaction of a TiO2-supported cobalt catalyst in a continuous stirred tank reactor and compared to the later stages. Thus, both short-term and long-term experiments were performed starting with fresh catalysts in each case. The experimental results showed that stirrer speed had an influence on the Fischer−Tropsch performance only in the short term. This suggested that under typical reaction conditions in a gas−solid system, long-term the Fischer−Tropsch reaction is not controlled by external mass transfer. After between about 30 and 80 h (depending on the temperature), large changes in reaction rate and product selectivity were observed, and these time-on-stream experiments showed that these changes were caused neither by the reaction conditions nor by the external mass transfer. Two possible explanations are proposed. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie1011933

Study of radial heat transfer in a tubular fischer - tropsch synthesis reactor / Xiaowei Zhu 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. 10682-10688 Titre : Study of radial heat transfer in a tubular fischer - tropsch synthesis reactor Type de document : texte imprimé Auteurs : Xiaowei Zhu, Auteur ; Xiaojun Lu, Auteur ; Xinying Liu, Auteur Année de publication : 2011 Article en page(s) : pp. 10682-10688 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Reactor  Fischer  Tropsch  synthesis  Heat  transfer Résumé : A series of experiments were performed to investigate and compare the heat transfer characteristics of a catalyst bed during the Fischer-Tropsch synthesis (FTS) reaction and heating without the reaction. A Co/ TiO2 catalyst was used in a relatively large internal diameter (ID) tubular reactor. In the first set of experiments, the bed was run under typical low-temperature FTS conditions, while in the second set an inert gas was fed to the bed and a heater with variable heat output was used along the center axis of the catalytic bed to generate the temperature profile. The two-dimensional (radial and axial) temperature profiles in the bed in both cases were measured for varying flow rates and reactor wall temperatures. Simple radial heat transfer models were derived for these two sets of experiments, and the effective thermal conductivity coefficients of the catalyst bed were estimated. Comparisons of the results showed that there were considerable differences between the values of the coefficients and in the shape of the temperature profiles in the reaction and nonreaction cases. This suggests that the liquid formed during the reaction may play an important role in affecting the heat transfer characteristics of the catalyst bed. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447961 [article] Study of radial heat transfer in a tubular fischer - tropsch synthesis reactor [texte imprimé] / Xiaowei Zhu, Auteur ; Xiaojun Lu, Auteur ; Xinying Liu, Auteur . - 2011 . - pp. 10682-10688. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 21 (Novembre 2010) . - pp. 10682-10688 Mots-clés : Reactor  Fischer  Tropsch  synthesis  Heat  transfer Résumé : A series of experiments were performed to investigate and compare the heat transfer characteristics of a catalyst bed during the Fischer-Tropsch synthesis (FTS) reaction and heating without the reaction. A Co/ TiO2 catalyst was used in a relatively large internal diameter (ID) tubular reactor. In the first set of experiments, the bed was run under typical low-temperature FTS conditions, while in the second set an inert gas was fed to the bed and a heater with variable heat output was used along the center axis of the catalytic bed to generate the temperature profile. The two-dimensional (radial and axial) temperature profiles in the bed in both cases were measured for varying flow rates and reactor wall temperatures. Simple radial heat transfer models were derived for these two sets of experiments, and the effective thermal conductivity coefficients of the catalyst bed were estimated. Comparisons of the results showed that there were considerable differences between the values of the coefficients and in the shape of the temperature profiles in the reaction and nonreaction cases. This suggests that the liquid formed during the reaction may play an important role in affecting the heat transfer characteristics of the catalyst bed. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=23447961

A Thermodynamic approach to olefin product distribution in fischer–tropsch synthesis / Xiaojun Lu in Industrial & engineering chemistry research, Vol. 51 N° 51 (Décembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 51 (Décembre 2012) . - pp. 16544-16551 Titre : A Thermodynamic approach to olefin product distribution in fischer–tropsch synthesis Type de document : texte imprimé Auteurs : Xiaojun Lu, Auteur ; Diane Hildebrandt, Auteur ; Xinying Liu, Auteur Année de publication : 2012 Article en page(s) : pp. 16544-16551 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Fischer  Tropsch  synthesis Résumé : Conventional Fischer―Tropsch (FT) experiments were performed in both a continuously stirred tank reactor (CSTR) and a plug-flow reactor (PFR) on a TiO2-supported cobalt catalyst. The olefin/paraffin ratios for short-chain hydrocarbons (C2―C5) were found to change when the reaction conditions were kept constant in a CSTR, while the ratio of adjacent olefins (for example, C4H8/C3H6) remained unchanged. In the experiments with a fixed-bed reactor, the temperature was varied from 210―250 °C and different flow rates ranging from 1.8―5.4 NL h―1 g-cat―1. The ratio of adjacent olefins was found to be constant under these conditions as well. After proposing a thermodynamic model for olefin product distribution, we compared the results that the model predicted with those obtained in the experiments, and found that there is good agreement between the thermodynamic predictions and the measured distributions. This supports the postulation that the olefin distribution in the Fischer-Tropsch synthesis (FTS) reaction might be determined by thermodynamics. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26755617 [article] A Thermodynamic approach to olefin product distribution in fischer–tropsch synthesis [texte imprimé] / Xiaojun Lu, Auteur ; Diane Hildebrandt, Auteur ; Xinying Liu, Auteur . - 2012 . - pp. 16544-16551. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 51 (Décembre 2012) . - pp. 16544-16551 Mots-clés : Fischer  Tropsch  synthesis Résumé : Conventional Fischer―Tropsch (FT) experiments were performed in both a continuously stirred tank reactor (CSTR) and a plug-flow reactor (PFR) on a TiO2-supported cobalt catalyst. The olefin/paraffin ratios for short-chain hydrocarbons (C2―C5) were found to change when the reaction conditions were kept constant in a CSTR, while the ratio of adjacent olefins (for example, C4H8/C3H6) remained unchanged. In the experiments with a fixed-bed reactor, the temperature was varied from 210―250 °C and different flow rates ranging from 1.8―5.4 NL h―1 g-cat―1. The ratio of adjacent olefins was found to be constant under these conditions as well. After proposing a thermodynamic model for olefin product distribution, we compared the results that the model predicted with those obtained in the experiments, and found that there is good agreement between the thermodynamic predictions and the measured distributions. This supports the postulation that the olefin distribution in the Fischer-Tropsch synthesis (FTS) reaction might be determined by thermodynamics. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26755617