文献类型：期刊文献

英文题名：CO Activation Pathways of Fischer-Tropsch Synthesis on χ-Fe5C2 (510): Direct versus Hydrogen-Assisted CO Dissociation

作者：Thanh Hai Pham[1];Duan, Xuezhi[1];Qian, Gang[1];Zhou, Xinggui[1];Chen, De[2]

机构：[1]E China Univ Sci & Technol, State Key Lab Chem Engn, Shanghai 200237, Peoples R China;[2]Norwegian Univ Sci & Technol, Dept Chem Engn, N-7491 Trondheim, Norway

年份：2014

卷号：118

期号：19

起止页码：10170

外文期刊名：JOURNAL OF PHYSICAL CHEMISTRY C

收录：;EI(收录号：20142117750164);WOS:【SCI-EXPANDED(收录号:WOS:000336198900036)】；

基金：This work is financially supported by the Natural Science Foundation of China (21306046), the China Postdoctoral Science Foundation (2012M520041 and 2013T60428), and the 111 Project of Ministry of Education of China (B08021).

语种：英文

外文关键词：Electronic properties - Chemical bonds - Hydrogen - Fischer-Tropsch synthesis - Activation analysis - Carbides - Iron compounds - Binding energy - Dissociation - Activation energy

摘要：Iron carbides, especially chi-Fe5C2, among the active iron species in Fischer-Tropsch synthesis (FTS), are considered to be responsible for high FTS activity. CO activation pathways as the initial steps of FTS over chi-Fe5C2 were explored by spin-polarized density functional theory calculations. Surface energies of chi-Fe5C2 facets observed from the XRD patterns were first calculated, and then the corresponding equilibrium chi-Fe5C2 shape was obtained by Wulff construction. The thermodynamically stable (510) surface was predicted to have the largest percentage among the exposed crystal facets. Subsequently, the adsorption properties of CO on chi-Fe5C2 (510) were studied. Despite exhibiting lower binding energy than that at the 3F-4 site as the most stable configuration, CO adsorption at the 4F-1 site led to significant weakening of the C-O bond from both the structural and electronic properties' points of view. Furthermore, two kinds of CO activation mechanisms (i.e., the direct and H-assisted CO dissociation) and the corresponding six kinds of CO activation pathways on chi-Fe5C2 (510) were comparatively investigated on the basis of the evolution of carbon species, in which the C-O bond cleavage and further hydrogenation of surface species were concerned. The systematic analysis of the activation properties of CO suggests the direct CO dissociation as the preferred activation pathway.