Journal of Catalysis, Vol.271, No.2, 195-200, 2010
Direct oxidation of methane to methanol over proton conductor/metal mixed catalysts
The intermediate-temperature and low-pressure production of methanol from methane in a one-pass process was investigated using a micro- or nanosized electrocatalyst system. The powdered catalyst was prepared by mixing proton-conducting Sn0.9In0.1P2O7 particles with high-activity Pd-Au-Cu/C particles to provide numerous electrolyte-electrode interfaces as reaction sites for methane oxidation. For a feed mixture of H2O, O-2, and methane, a local electrochemical cell can be formed at the electrode-electrolyte interface: H2O -> 1/2O(2) + 2H(+) + 2e(-) at the anode site; O-2 + CH4 + 2H(+) + 2e(-) -> CH3OH + H2O at the cathode site. In addition, the electrode also functions as a lead wire that short-circuits the cell. Therefore, the overall reaction can be expected to be CH4 + 1/2O(2) CH3OH. The series of reactions successfully resulted in reduction in the temperature for initiation of methane oxidation to 250 degrees C and increased the methanol yield while maintaining a very high selectivity toward methanol for temperatures up to 400 degrees C. (C) 2010 Elsevier Inc. All rights reserved.