Dry reforming of methane by microsecond pulsed dielectric barrier discharge plasma: Optimizing the reactor structures

Dry reforming of CH4 process can convert greenhouse gases into high-value-added fuels and chemicals with its broad application prospects in environmental protection and renewable energy. Non-thermal plasma is considered an effective alternative method because it can activate CH4 and CO2 under low temperature and atmospheric pressure. This paper is aimed to optimize the plasma-assisted dry reforming of CH4 process in a unipolar microsecond pulsed coaxial dielectric barrier discharge by investigating the effects of reactor structures. The results show that the conversions of reactants and the yields of syngas were significantly affected by the reactor structures. Specifically, a multi-stage or foil external electrode and negative polar discharge could promote CH4 and CO2 conversions, gas product yields, and energy conversion efficiencies. For different electrodes, the maximal conversions of CH4 and CO2 were 20.4% and 14.1%, with an energy conversion efficiency of 4.4% under our experimental conditions. Higher conversions, yields, and energy conversion efficiencies were obtained with lower power input when applying heat insulation measures. CH4 conversion was promoted to 27.9% with a moderate energy conversion efficiency of 3.8%, but the conversion of CO2 was only 12% when packing materials into the reactor. The results can provide specific guidance for designing plasma or plasma-catalytic dry reforming reactor.