Highly active and stable Ru‐promoted Ni/<scp>CeO₂</scp> catalysts for <scp>CO₂</scp> methanation reaction

Abstract Biogas is not only a promising renewable source of energy that can be integrated into existing infrastructures, but biogas could also be a CO 2 source for green methane synthesis by hydrogenation with renewable energy‐derived hydrogen. Since biogas is a mixture of CO 2 and CH 4 , we targeted to accomplish direct methanation of CO 2 in CH 4 ‐rich gases that are supposed to be a simulated biogas without any processes for CH 4 and CO 2 separation in biogas. This direct CO 2 methanation in biogas can be a more sustainable and environmentally friendly approach. Methane production from biogas‐derived CO 2 by conventional methods has some difficulties, including (1) the vast energy cost for separation process of CO 2 and CH 4 and (2) the slow rate of the reaction in biochemical CO 2 methanation. In this paper, we developed active and durable catalysts in direct methanation of CO 2 contained in biogas. The focus was on the effect of coexisting CH 4 and steam in biogas on CO 2 methanation activity and durability of CeO 2 supported Ni catalysts. Among all prepared catalysts, a 1 wt.% Ru‐10 wt.% Ni/CeO 2 catalyst exhibited 90% CO 2 conversion and 100% CH 4 selectivity at 275°C reaction temperature. Adding steam to the standard reaction gas mixture (CO 2 /H 2 /N 2 = 1/4/5) did not impact CO 2 conversion in the temperature range investigated, whereas adding CH 4 to the standard reaction gas mixture had only a minute decrease (i.e., 86.9% CO 2 conversion and 100% CH 4 selectivity at 275°C temperature). Furthermore, the 1 wt.% Ru‐10 wt.% Ni/CeO 2 catalyst demonstrated remarkable stability in the CO 2 methanation reaction.