New highly active catalysts in direct partial oxidation of methane to synthesis gas

Catalysts for oxidation of methane with a CH4/O-2 ratio of 2 were classified in three groups. Group one contains catalysts with reducible metals. They are active for full oxidation of methane in the presence of oxygen, followed by reforming of methane with CO2 and H2O to CO and H-2 after full oxygen conversion. The second group contains perovskite catalysts with irreducible bulk transition metals and is active only for full oxidation of methane. The third group contains the irreducible metal oxides that are active for direct partial oxidation next to full oxidation. Yttria/zirconia from this last group is active for direct partial oxidation via CH4 + O-2 --> CO + H-2 + H2O. A mechanism via methoxy and formaldehyde intermediates is proposed for this reaction.