Fundamental studies of CH₃OH oxidation over well-defined supported V₂O₅ catalysts

Methanol oxidation over supported V₂O₅ catalysts has received much interest in recent years because this catalytic reaction system represents a nice model for selective oxidation catalysis. In order to establish the molecular/electronic structure-activity/selectivity relationships, both CH₃OH-TPSR and steady-state studies with well-defined supported V₂O₅ catalysts were undertaken. The methanol oxidation TOF was found to be identical for isolated and polymerized surface VO₄ units on the same support in the sub-monolayer region. Relatively inactive crystalline V₂O₅ nanoparticles are also present above monolayer coverage and primarily decrease the number of exposed surface VO₄ catalytic active sites. The most dramatic effect on activity was observed when the specific oxide support was varied (∼103). The significant effect of the specific oxide support ligand and the absence of any effect of surface vanadia coverage (surface VO₄ polymer/monomer ratio), implicates the bridging V-O-Support bond as the catalytic active site for this and other redox reactions.