Parametric analysis of plasma-assisted pulsed dry methane reforming over Ni/Al2O3 catalyst

Pulsed dry methane reforming (DMR) with CH4/CO2 ratios of 0.5-2.0 was investigated in a dielectric barrier discharge (DBD) and Ni/Al2O3 hybrid reaction. A pulsed CH4 supply allows alternating DMR and de-coking reactions, thus enabling reaction diagnostics without serious catalyst deactivation by coking. Parametric changes in the CH4/CO2 ratio were used to probe the rate-determining step and synergistic effect induced by DBD. Nonthermal plasma-activated CO2 and H2O were found to be key factors for enhancing the H-2 and CO yields and CO2 conversion. In contrast, CH4 conversion was not clearly enhanced by DBD at fixed temperatures near 550 degrees C. Moreover, based on experimental observations, a tentative mechanism was proposed wherein a trace amount of plasma-excited H2O catalytically promoted solid carbon oxidation.