Highly active and stable Ru/κ-Al2O3 catalyst for CO2 methanation

CO 2 methanation over the Al 2 O 3 supported Ru catalyst attracts increasing attentions because of the importance of Al 2 O 3 as an industrial support. However, the activity of the developed Ru/Al 2 O 3 catalysts is not sufficiently high. Here, we confirmed that kappa alumina (κ-Al 2 O 3 ) is an excellent support for ruthenium (Ru) nanocluster catalyst with a significantly higher activity for CO 2 methanation, compared to the γ-Al 2 O 3 supported Ru catalyst. In addition, the Ru/κ-Al 2 O 3 catalyst retains its structural stability up to 1000-h with a sustained CO 2 conversion of 70% and nearly 100% CH 4 selectivity at 325 °C as illustrated. The catalyst characterization reveals that an electronic metal-support interaction (EMSI) exists between Ru and κ-Al 2 O 3 with unsaturated defect sites, which promotes H 2 dissociation and spillover on Ru nanoclusters while strengthening CO 2 adsorption. Density functional theory (DFT) calculations also verify the unique EMSI between Ru nanoclusters and κ-Al 2 O 3 with active interface sites for enhanced CO 2 adsorption and subsequently improved methanation via the CO pathway. This study offers critical insights for the design and preparation of highly active and stable catalysts for CO 2 methanation with alumina support.