Insight into the preference mechanism for Csingle bondC chain formation of C2 oxygenates and the effect of promoters in syngas conversion over Cu-based catalysts

Authors: Guiru Wang, Riguang Zhang, Baojun Wang

Abstract:
Cu-based catalysts are often used for the production of C₂ oxygenates or hydrocarbons from syngas, although numerous studies have been reported, the exact mechanism remains in debate, and presents a major challenge in catalysis. In this study, the preference mechanism for C=C chain formation of C₂ oxygenates and the role of promoters in syngas conversion on Cu(2 1 1) and metal-doped MCu(2 1 1) (M = Rh, Ni) surfaces, including CH_x (x = 1–3) hydrogenation, dissociation and coupling, as well as CO or CHO insertion into CH_x (x = 1–3), have been systematically investigated by using density functionaltheory method. Our results show that pure Cu(2 1 1) surface shows a better catalytic activity to C₂H₄ formation rather than C2 oxygenates. However, promoters Rh and Ni-doped Cu(2 1 1) surfaces show a better activity and selectivity to C2 oxygenates rather than hydrocarbons, in which CH₂ species is responsible for C₂ oxygenates formation by CHO insertion. In addition, the difference between CO and CHO insertion into CH_x (x = 1–3) to form C₂ oxygenates is mainly attributed to the HOMO–LUMO gap of CH_x CHO and CH_x CO, the smaller HOMO–LUMO gap greatly facilitates the charge transfer and hybridization between adsorbed species and catalysts.

Keywords:
C₂ oxygenates
Mechanism Cu(2 1 1)
Metal-doped Cu(2 1 1)
Density functional theory

Published in: Applied catalysis A: General  (Volume 466, Pages 1-314, 10 September 2013)

Publisher: Elsevier  

ISSN Information: 0926-860X

Insight into the preference mechanism for Csingle bondC chain formation of C2 oxygenates and the effect of promoters in syngas conversion over Cu-based catalysts

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