DIMERIZATION OF METHANE THROUGH MICROWAVE PLASMAS

Methane is converted to saturated and unsaturated C2 hydrocarbons in microwave plasma reactors at pressures from 10 to 100 Torr. The microwave power is coupled to the plasma through either an Evenson or a Beenakker cavity, with the Beenakker cavity giving better results. The conversion of methane depends on the pressure, power input, and the flow rate and can be as high as 90%. A simple kinetic model based on collision theory relates conversion to experimental variables. The selectivity to unsaturated C2 products varies from 0 to 50% with the maximum selectivity occurring around 20% methane conversion. The energy efficiency of utilizing microwave energy to drive the thermodynamically unfavorable reaction of methane dimerization ranges from 0.2% to 3.3%.