Methane coupling by a parallel-electrodes pulsed gliding plasma: A strong correlation between conversion ability and the plasma mobility

Abstract

The coupling of methane using a highly mobile nanosecond pulsed plasma is examined. A stroboscopic imaging system is used to determine the drift velocity of the plasma column (vd). When vd varies within a narrow range of 1.2–2.2 m/s in CO2 + CH4 plasma, the energy efficiency increases from 35% to over 60% showing very sensitive correlation. The reactants conversion rates also increase linearly with vd, ranging from 40 to 60%. Yields of ethylene and ethane monotonically increases with vd when pure methane is introduced. A mathematical model predicts a high spatial overlap of successive plasma pulses, with an overlap of 78% at the highest vd obtained here. This overlap, inversely related to vd, negatively affects on the process due to energy dissipation by products and high temperatures in the overlap zone. To address the problem of low conversion rates or efficiencies of plasmas, using non-overlapping plasma reactors may be a viable solution.