V2O5SiO2-catalyzed methane partial oxidation with molecular oxygen

The partial oxidation of methane to formaldehyde by molecular oxygen has been studied using vanadium(V) oxide-silica catalysts in the temperature range 773–873 K at 1 atm pressure. Although HCHO selectivity in excess of 70% was observed at very low conversions, it was found to decrease rapidly as the extent of reaction was increased. At the highest conversions studied (6.4%), carbon monoxide was the principal reaction product. Methane oxidation was found to follow a sequential reaction path, where formaldehyde is formed from methane, carbon monoxide from formaldehyde, and carbon dioxide from carbon monoxide. This is in contrast to the molybdenum(VI) oxide-silica-catalyzed reaction, where CO2 is formed directly from methane in a parallel pathway. A model has been constructed based on the sequential mechanism and experimentally derived kinetic parameters. It accounts for the observed selectivity and conversion behavior of this Catalyst.