Efficient and selective formation of methanol from methane in a fuel cell-type reactor

Direct oxidation of methane to methanol at low temperatures was investigated using a fuel cell-type reactor, where a mixture of methane and H2O vapor was supplied to the anode and air to the cathode. Methanol was scarcely produced over a Pt/C anode from 50 to 250 °C. However, through trial and error, the production of methanol over a V2O5/SnO2 anode was significant at 100 °C; the current efficiency for methanol production and the selectivity toward methanol were as high as 61.4% and 88.4%, respectively. Methanol was produced by the reaction of methane with an active oxygen species over the V2O5 catalyst. Cyclic voltammetry of the anode indicated that the generation of such active oxygen species was strongly dependent on the anode potential. Moreover, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy measurements confirmed that highly dispersed and partially reduced vanadium species were present on the SnO2 surface. These vanadium species are considered to be active sites for the formation of the active oxygen species, probably anion radicals (image and Oradical dot−).