Ethanol Synthesis from Syngas on the Stepped Rh(211) Surface: Effect of Surface Structure and Composition

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• 作者：Jiancheng Wang ; Zhixue Liu ; Riguang Zhang ; Baojun Wang
• 刊名：Journal of Physical Chemistry C
• 出版年：2014
• 出版时间：October 2, 2014
• 年：2014
• 卷：118
• 期：39
• 页码：22691-22701
• 全文大小：800K
• ISSN：1932-7455

文摘

The mechanisms of ethanol synthesis from syngas including CH_x (x = 1鈥?) species and C₂ oxygenates on the stepped Rh(211) surface have been systematically investigated by using density functional theory together with a periodic slab model. Our results show that among all CH_x (x = 1鈥?) species, CH₃ is the most favorable monomer, which is more favorable than CH₃OH formation; this result is quite different from that on the flat Rh(111). Beginning with CH₃ species, CH₃ + CHO 鈫?CH₃CHO dominantly contributes to the formation of C₂ oxygenates; subsequently, CH₃CHO is successively hydrogenated to ethanol via CH₃CH₂O intermediate. Meanwhile, CH₄ formation by CH₃ hydrogenation is energetically compatible with CH₃CHO formation; that is, the productivity and selectivity of ethanol is determined by the formations of CH₃CHO and CH₄. As a result, the strategy of improving the Rh-based catalyst with the help from the promoter Mn is employed to tune the relative activity of CH₃CHO and CH₄ formations that control the productivity and selectivity of ethanol from syngas. Our results show that the productivity and selectivity of ethanol from syngas can be improved by introducing promoter Mn into the Rh catalyst.