XPS study of MoO2, WO2 and WO3 and their catalytic activities in the izomerization reactions of alkanes

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.