期刊
APPLIED CATALYSIS B-ENVIRONMENTAL
卷 197, 期 -, 页码 324-336出版社
ELSEVIER
DOI: 10.1016/j.apcatb.2016.04.004
关键词
Methane activation; Density functional theory; CeO2; Transition metal doping
资金
- European FP7 NMP project BIOGO [604296]
- COST ACTION CM1104 Reducible oxides: structure and function
- Science Foundation Ireland (SFI) Irish Centre for High-end Computing (ICHEC)
- SFI at Tyndall
The development of economical heterogeneous catalysts for the activation of methane is a major challenge for the chemical industry. Screening potential candidates becomes more feasible using rational catalyst design to understand the activity of potential catalysts for CH4 activation. The focus of the present paper is the use of density functional theory to examine and elucidate the properties of doped CeO2. We dope with Cu and Zn transition metals having variable oxidation state (Cu), and a single oxidation state (Zn), and study the activation of methane. Zn is a divalent dopant and Cu can have a +1 or +2 oxidation state. Both Cu and Zn dopants have an oxidation state of +2 after incorporation into the CeO2 (111) surface; however a Hubbard +U correction (+U = 7) on the Cu 3d states is required to maintain this oxidation state when the surface interacts with adsorbed species. Dissociation of methane is found to occur locally at the dopant cations, and is thermodynamically and kinetically more favorable on Zn-doped CeO2 than Cu-doped CeO2. The origins of this lie with the Zn(II) dopant moving towards a square pyramidal geometry in the sub surface layer which facilitates the formation of two-coordinated surface oxygen atoms, that are more beneficial for methane activation on a reducible oxide surface. These findings can aid in rational experimental catalyst design for further exploration in methane activation processes. (C) 2016 Elsevier B.V. All rights reserved.
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