Insight into the Preference Mechanism of CHx (x = 1鈥?) and C鈥揅 Chain Formation Involved in C2 Oxygenate Formation from Syngas on the Cu(110) Surface

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• 作者：Riguang Zhang ; Xuancheng Sun ; Baojun Wang
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：April 4, 2013
• 年：2013
• 卷：117
• 期：13
• 页码：6594-6606
• 全文大小：814K
• 年卷期：v.117,no.13(April 4, 2013)
• ISSN：1932-7455

文摘

The possible formation pathways of CH_x (x = 1鈥?) and C鈥揅 chain involved in C₂ oxygenate formation from syngas on an open Cu(110) surface have been systematically investigated to identify the preference mechanism of CH_x (x = 1鈥?) and C鈥揅 chain formation. Here, we present the main results obtained from periodic density functional calculations. Our results show that all CH_x (x = 1鈥?) species formation starts with CHO hydrogenation; among them, CH_x (x = 2, 3) are the most favored monomers, however, CH₃OH is the main product from syngas on the Cu(110) surface, and the formation of CH_x (x = 1鈥?) cannot compete with CH₃OH formation. Further, on the basis of the favored monomer CH_x (x = 2, 3), we probe into the C鈥揅 chain formation of C₂ oxygenates by CO or CHO insertion into CH_x (x = 2, 3), as well as the hydrogenation, dissociation, and coupling of CH_x (x = 2, 3), suggesting that CO insertion into CH₂ to form C₂ oxygenates is the dominant reaction for CH₂ on the Cu(110) surface with an activation barrier of 44.5 kJ路mol^鈥?; however, for CH₃, CH₃ hydrogenation to CH₄ is the dominant reaction on the Cu(110) surface with an activation barrier of 67.5 kJ路mol^鈥?. As a result, to achieve high productivity and selectivity for C₂ oxygenates from syngas, Cu has to get help from the promoters, which should be able to boost CH₂ formation and/or suppress CH₃OH and CH₃ formation. The present study provides the basis to understand and develop novel Cu-based catalysts for C₂ oxygenate formation from syngas.