Dry reforming reactions of CH4 over CeO2/MgO catalysts at high concentrations of H2S, and behavior of CO2 at the CeO2-MgO interface

•Stable activity of CeO2/MgO was demonstrated in CH4 reforming with 2000 ppm H2S.•5 mol% CeO2/MgO exhibited comparable activity to that of pure CeO2.•No carbon deposition or phase change was observed after the reaction.•DRIFT and isotopic labeling showed CO2 at CeO2-MgO interface promoted the reaction.•SOx formed at the CeO2-MgO interface supplies oxygen to the CeO2 surface.