Raising the CO_x Methanation Activity of a Ru/γ-Al₂ O₃ Catalyst by Activated Modification of Metal-Support Interactions

Ru/Al₂ O₃ is a highly stable, but less active catalyst for methanation reactions. Herein we report an effective approach to significantly improve its performance in the methanation of CO₂ /H₂ mixtures. Highly active and stable Ru/γ-Al₂ O₃ catalysts were prepared by high-temperature treatment in the reductive reaction gas. Operando/in situ spectroscopy and STEM imaging reveals that the strongly improved activity, by factors of 5 and 14 for CO and CO₂ methanation, is accompanied by a flattening of the Ru nanoparticles and the formation of highly basic hydroxylated alumina sites. We propose a modification of the metal-support interactions (MSIs) as the origin of the increased activity, caused by modification of the Al₂ O₃ surface in the reductive atmosphere and an increased thermal mobility of the Ru nanoparticles, allowing their transfer to modified surface sites.