Hydrogen‐Atom Abstraction from Methane by Stoichiometric Vanadium–Silicon Heteronuclear Oxide Cluster Cations

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阅读量：

131

作者：

XL Ding，YX Zhao，XN Wu，ZC Wang，JB Ma，SG He

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摘要：

Vanadiumsilicon heteronuclear oxide cluster cations were prepared by laser ablation of a V/Si mixed sample in an O2 background. Reactions of the heteronuclear oxide cations with methane in a fast-flow reactor were studied with a time-of-flight (TOF) mass spectrometer to detect the cluster distribution before and after the reactions. Hydrogen abstraction reactions were identified over stoichiometric cluster cations [(V2O5)n(SiO2)m]+ (n=1, m=14; n=2, m=1), and the estimated first-order rate constants for the reactions were close to that of the homonuclear oxide cluster V4O10+ with methane. Density functional calculations were performed to study the structural, bonding, electronic, and reactivity properties of these stoichiometric oxide clusters. Terminal-oxygen-centered radicals (Ot.) were found in all of the stable isomers. These Ot. radicals are active sites of the clusters in reaction with CH4. The Ot. radicals in [V2O5(SiO2)14]+ clusters are bonded with Si rather than V atoms. All the hydrogen abstraction reactions are favorable both thermodynamically and kinetically. This work reveals the unique properties of metal/nonmetal heteronuclear oxide clusters, and may provide new insights into CH4 activation on silica-supported vanadium oxide catalysts.

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关键词：

CH activation cluster compounds density functional calculations mass spectrometry methane activation radicals

DOI：

10.1002/chem.201001297

被引量：

344

年份：

2010