The relationship between structure and activity of Pt-WOx/SiO2 catalysts for selective cleavage of C[sbnd]O bond in glycerol and 1,4-anhydroerythritol was investigated. Characterization results showed that various types of W species were present depending on the W amount: W-Pt alloy, WOx species with low coordination numbers on Pt particle surface, submonolayer/monolayer on SiO2, and so on. In Pt-WOx/SiO2 (4 wt% Pt, W/Pt = 0.25) catalyst with the optimized W amount, WOx species (average valence of W: +4 from XAS) were located between Pt particles and SiO2 as shown by the disappearing W signal in XPS. These Pt-WOx interface sites can be the active site for the dissociation of C[sbnd]O bond. The interaction between Pt particles and WOx over non-pre-reduced catalyst can be further enhanced by the migration of high valent WOx species (+6) in the presence of water solvent to form the Pt-WOx interface between Pt particles and SiO2 more effectively.
- Heterogeneous catalysis