621 SELECTING OXYGEN SOURCE FOR PARTIAL OXIDATION OF METHANE TO METHANOL USING MICROWAVE PLASMAS M.V. BADANI1, J. HUANG1, S.L. SUIB1,2,3*, J.B. HARRISON4, and M. KABLAUOI4 1 Department of Chemistry, U-60, University of Connecticut, Storrs, Connecticut 06269-3060 U.S.A. 2Department of Chemical Engineering 3Institute of MaterialsScience 4Texaco Research Centre, Texaco Inc., P.O. Box 509, Beacon, NY 12508U.S.A. Received 30 December 1994;accepted 25 January 1995 Abstract--The methanol selectivity in partial oxidation of methane in microwave plasma reactors is improved by using H2O in the presence or absence of O2. The use of H2O2 as an oxygen sourcehas a similar effect, although it is less effectivethan H2O. The addition of H2 to the system has littleeffect on selectivity. Two pathways are suggested for the formation of methanol. One involves a CH3O* or CH3O2* intermediate, while the other involvesa direct combination of H3* and OH* radicals. The first pathway is favored in the presence of O2 whilethe latter is favored in the presence of H 2O or H2O2. The best resultsare obtained for the CH4-O2-H2O system when methanol is formed through both pathways. INTRODUCTION The conversion of methane into more useful chemicals, such as methanol, is an important research topic. At present, methanol is commercially produced from methane through steam reforming of methane into synthesis gas, which is then converted to methanol over copper based catalysis [1]. The direct partial oxidation of methane is a more efficient process [2- 9]. However, up to the present time, all the processes studied are impractical because of the raw material cost, the operating cost, or the difficulty of separating methanol from other products. Alternative routes, such as plasma reactions, should be explored [10-19]. Shepelev et al. studied oxidative conversion of methane in alternate current discharges [ 11 ]. They achieved 20% selectivity of methanol from methane. Murphy et al. reported on the microwave plasma conversion of methane and carbon dioxide to syn-gas and the conversion of methane to C2 hydrocarbons in the presence of hydrogen and plasma initiaters [12-14]. We reported on the dimerization of methane using microwave plasmas with 95% selectivity to C2 hydrocarbons at conversions ranging from 30 to 90% [18]. We also studied the