A DIRECT, CONTINUOUS, LOW-POWER CATALYTIC CONVERSION OF METHANE TO HIGHER HYDROCARBONS VIA MICROWAVE PLASMAS

A selective, direct, continuous, low-power catalytic conversion of methane to higher energy hydrocarhons via microwave plasma methods has been developed in the pressure range 10 to 50 Torr. Methane can be converted to ethane, ethylene, and acetylene in different selectivities depending on the power of the plasma, flow rate, nature of the catalyst, and pressure in the system. Selectivities for ethane can be as high as 77%, for ethylene 25%, and for acetylene 25%. Conversions of methane as high as 52% have been realized. Coking can be minimized by proper choice of catalyst and high flow rates. Ethane and ethylene can be converted with 100% selectivity to ethylene and acetylene, respectively, in a similar process. Radicals are important in these transformations, with the catalyst surface providing sites for radical combination. Rates of reaction, energy balances, and mechanisms of reaction are discussed. © 1993 Academic Press, Inc.