Hydrogen-transfer dehydration between alcohols over V2O3 and MoO2 catalysts for the formation of corresponding alkanes and aldehydes

Abstract

Conversion of alcohols in a gas phase under N2 flow at 573K was carried out using V2O3 and MoO2 oxides with low valence oxidation states. It was found in the reaction of ethanol that equimolar amounts of ethane and acetaldehyde were catalytically formed as the main products over the oxides. Bi-products were small amounts of ethene and C4 compounds. Reactions of other alcohols (methanol, 1-propanol and 2-propanol) over the V2O3 and MoO2 catalysts also led to the equimolar formation of corresponding alkanes and aldehydes or ketone. It was confirmed by XRD and XPS that the low valence states of V2O3 and MoO2 were unchanged during the reactions and the oxides stably worked as the catalyst. Based on catalytic reaction results obtained under various reaction conditions (reaction temperature, contact time, introduction of H2 and C2H4 into reaction stream) and on experiments of kinetic isotope effects on the ethanol reaction, a reaction scheme is proposed, in which hydrogen transfer reaction between two alcohol molecules adsorbed on metal–O2−–metal sites on the surface of V2O3 and MoO2 catalysts takes place via 6-membered transition state, followed by dehydration.