文献类型：期刊文献

英文题名：Activity and coke formation of nickel and nickel carbide in dry reforming: A deactivation scheme from density functional theory

作者：Wang, Ziyun[1];Cao, X. -M.[2,3];Zhu, Jinghao[2,3];Hu, P.[1]

机构：[1]Queens Univ Belfast, Sch Chem & Chem Engn, Belfast BT9 5AG, Antrim, North Ireland;[2]E China Univ Sci & Technol, Ctr Computat, State Key Lab Chem Engn, Shanghai 200237, Peoples R China;[3]E China Univ Sci & Technol, Res Inst Ind Catalysis, Shanghai 200237, Peoples R China

年份：2014

卷号：311

起止页码：469

外文期刊名：JOURNAL OF CATALYSIS

收录：;EI(收录号：20140717306311);WOS:【SCI-EXPANDED(收录号:WOS:000333489500050)】；

基金：The authors thank the financial support from National Natural Science Foundation of China (21333003 and 21303051) and "111" programme (B08021). The authors gratefully acknowledge Queen's University of Belfast, UK's national high performance computing service HECToR (for which access was obtained via the UKCP consortium) and National Supercomputer Center in Jinan for computing time. Z.W. thanks Queen's University of Belfast for a Ph.D. studentship.

语种：英文

外文关键词：Dry reforming; Coke formation; Deactivation; Nickel; Nickel carbide; Methane; CO2; DFT; Microkinetics

摘要：Dry reforming is a promising reaction to utilise the greenhouse gases CO2 and CH4. Nickel-based catalysts are the most popular catalysts for the reaction, and the coke formation on the catalysts is the main obstacle to the commercialisation of dry reforming. In this study, the whole reaction network of dry reformation on both flat and stepped nickel catalysts (Ni(111) and Ni(211)) as well as nickel carbide (flat: Ni3C(001); stepped: Ni3C(111)) is investigated using density functional theory calculations. The overall reaction energy profiles in the free energy landscape are obtained, and kinetic analyses are utilised to evaluate the activity of the four surfaces. By careful examination of our results, we find the following regarding the activity: (i) flat surfaces are more active than stepped surfaces for the dry reforming and (ii) metallic nickel catalysts are more active than those of nickel carbide, and therefore, the phase transformation from nickel to nickel carbide will reduce the activity. With respect to the coke formation, the following is found: (i) the coke formation probability can be measured by the rate ratio of CH oxidation pathway to C oxidation pathway (r(CH)/r(C)) and the barrier of CO dissociation, (ii) on Ni(111), the coke is unlikely to form, and (iii) the coke formations on the stepped surfaces of both nickel and nickel carbide can readily occur. A deactivation scheme, using which experimental results can be rationalised, is proposed. (C) 2014 Elsevier Inc. All rights reserved.