Understanding promotional effects of trace oxygen in CO2 methanation over Ni/ZrO2 catalysts

Abstract

Feed composition is crucial for gas-phase catalytic reactions but has rarely been studied in CO2 methanation. In this work, we studied the effect of impurities (i.e., N2, steam, and O2) on the activity of Ni/ZrO2 in CO2 methanation. The reducible ZrO2 favored the formation of oxygen vacancies, which enhanced CO2 adsorption and subsequent hydrogenation into methane. Interestingly, trace O2 enhanced CO2 methanation over Ni/ZrO2 due to the generation of more *OH groups facilitating the conversion of intermediates to methane.