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4887152 
Journal Article 
XPS study of MoO2, WO2 and WO3 and their catalytic activities in the izomerization reactions of alkanes 
Katrib, A; Logie, V; Peter, M; Wehrer, P; Hilaire, L; Maire, G 
1997 
Journal de Chimie Physique et de Physico-Chimie Biologique
ISSN: 0021-7689 
Societe Francaise de Chimie 
94 
11-12 
1923-1937 
English 
The X.P.S Spectra of MoO2, WO2 and WO3 are presented. It was revealed that these commercial MoO2 and WO2 samples are partially oxidized on the surface to the more stable MoO3 and WO3 states respectively, with the presence of Mo(V) and W(V) in the interfaces. In Situ reduction of these samples, by hydrogen at different temperatures enabled to reduce MoO3 or WO3 to lower oxidation states. Catalytic activities in terms of isomerization reactions of 2-methyl pentane reactant to 3-methyl pentane and n-hexane as major products were interpreted in terms of a bifunctional mechanism involving the two free valence electrons of MoO2 and WO2 (metallic site) and the -OH (Bronsted acidic site) on the sample surface. 
XPS; catalytic reactions; WO2; WO3; MoO2