Fischer鈥揟ropsch Synthesis Using H2/CO/CO2 Syngas Mixtures over an Iron Catalyst

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• 作者：Yali Yao ; Xinying Liu ; Diane Hildebrandt ; David Glasser
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2011
• 出版时间：October 5, 2011
• 年：2011
• 卷：50
• 期：19
• 页码：11002-11012
• 全文大小：1041K
• 年卷期：v.50,no.19(October 5, 2011)
• ISSN：1520-5045

文摘

A series of low-temperature Fischer鈥揟ropsch 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.