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Hydrogen‐Atom Abstraction from Methane by Stoichiometric Vanadium–Silicon Heteronuclear Oxide Cluster Cations
Author(s) -
Ding XunLei,
Zhao YanXia,
Wu XiaoNan,
Wang ZheChen,
Ma JiaBi,
He ShengGui
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201001297
Subject(s) - heteronuclear molecule , stoichiometry , silicon , cluster (spacecraft) , hydrogen , inorganic chemistry , vanadium , vanadium oxide , methane , oxide , chemistry , materials science , molecule , metallurgy , organic chemistry , computer science , programming language
Vanadium–silicon heteronuclear oxide cluster cations were prepared by laser ablation of a V/Si mixed sample in an O 2 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 [(V 2 O 5 ) n (SiO 2 ) m ] + ( n =1, m =1–4; n =2, m =1), and the estimated first‐order rate constants for the reactions were close to that of the homonuclear oxide cluster V 4 O 10 + 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 (O t . ) were found in all of the stable isomers. These O t . radicals are active sites of the clusters in reaction with CH 4 . The O t . radicals in [V 2 O 5 (SiO 2 ) 1–4 ] + 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 CH 4 activation on silica‐supported vanadium oxide catalysts.