Oxidative Dehydrogenation of Methanol to Formaldehyde by a Vanadium Oxide Cluster Supported on Rutile TiO2(110): Which Oxygen is Involved?

Isolated vanadia clusters supported on titania catalyze the oxidation of methanol to formaldehyde. We used density functional theory to determine the mechanism of this reaction and found a new pathway for the dissociative adsorption of methanol and the dehydrogenation of the methyl group. In this mechanism, methanol adsorbs dissociatively, by inserting into the double bond of the vanadyl group; the methoxy radical binds to the vanadium atom, whereas the hydrogen binds to the oxygen atom of the vanadyl. The dehydrogenation of the methyl group, which is the rate-limiting step, takes place by moving a H atom from CH3 onto an oxygen atom in the -V-O-Ti- group. The V-O bond is broken, and a HO-Ti group is formed.