The conversion of methane to acetylene in MW (microwave)-DC (direct current) hybrid plasma was studied. The effects of H₂/CH₄ ratio, flow rate and power on the reaction and the stability of the device were investigated. The energy efficiency of the MW-DC hybrid plasma device was increased with the increase of the flow rate. The conventional DC plasma column was split into tens of plasma filaments, which changed the erosion mode of the electrode from point erosion to face erosion. The conversion of methane and the yield of acetylene are increased with the increase of the feed power or decrease of the H₂/CH₄ ratio and flow rate. With a total flow rate of 760 L/min, H₂/CH₄ ratio of 0.9, DC power of 90 kW, MW power of 6 kW, the conversion of methane, yield of acetylene and specific energy of requirement (SER) could reach 84.4%, 63.8% and 10.8 kWh•kg^－1 respectively. The electrode life was extended to more than 200 h.

Key words: MW-DC hybrid plasma, natural gas, acetylene, long electrode life