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

Abstract

High concentrations of H2S are contained in unused industrial gases and biomass gasification gases, necessitating catalysts which are robust in the presence of H2S to produce H2 from them. Pure CeO2 is known for its robustness, but rare earth oxide consumption should be reduced to improve sustainability. Herein, a stable dry reforming reaction is demonstrated over CeO2/MgO under reaction conditions of 2000 ppm H2S. A comparable catalytic activity to pure CeO2 was exhibited by 5 mol% CeO2/MgO despite its low loading of CeO2. Further, no carbon deposition or impurity phases were formed in the catalyst after an 8-h reaction. Transmission electron microscopy revealed that MgO stabilized the CeO2 nanoparticles under these reaction conditions. Also, kinetic analyses, infrared spectroscopy, and isotopic labeling studies suggested that the CeO2-MgO interface strongly captures CO2 and supplies it to the CeO2 surface to accelerate the dry reforming reaction.