Modeling of the Kinetics for Methanol Synthesis using Cu/ZnO/Al2O3/ZrO2 Catalyst: Influence of Carbon Dioxide during Hydrogenation

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• 作者：Hye-Won Lim ; Myung-June Park ; Suk-Hwan Kang ; Ho-Jeong Chae ; Jong Wook Bae ; Ki-Won Jun
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2009
• 出版时间：December 2, 2009
• 年：2009
• 卷：48
• 期：23
• 页码：10448-10455
• 全文大小：185K
• 年卷期：v.48,no.23(December 2, 2009)
• ISSN：1520-5045

文摘

A kinetic model for methanol (MeOH) synthesis over Cu/ZnO/Al₂O₃/ZrO₂ catalyst has been developed and selected to evaluate the effect of carbon dioxide on the reaction rates due to its high activity and stability. Detailed kinetic mechanism, on the basis of different sites on Cu for the adsorption of carbon monoxide and carbon dioxide, is applied, and the water−gas shift (WGS) reaction is included in order to provide the relationship between the hydrogenations of carbon monoxide and carbon dioxide. Parameter estimation results show that, among 48 reaction rates from different combinations of rate determining steps (RDSs) in each reaction, the surface reaction of a methoxy species, the hydrogenation of a formate intermediate HCO₂, and the formation of a formate intermediate are the RDS for CO and CO₂ hydrogenations and the WGS reaction, respectively. It is shown that the CO₂ hydrogenation rate is much lower than the CO hydrogenation rate, and this affects the methanol production rate. However, carbon dioxide decreases the WGS reaction rate, which prevents methanol from converting to dimethyl ether, a byproduct. In such a way, a small fraction of carbon dioxide accelerates the production of methanol indirectly within a limited range, showing a threshold value of the CO₂ fraction for the maximum methanol synthesis.