Raising the COx Methanation Activity of a Ru/γ-Al2O3 Catalyst by Activated Modification of Metal-Support Interactions.

Ru/Al 2 O 3 is a highly stable, but less active catalyst for methanation reactions. Here we report an effective approach to significantly improve its performance in the methanation of CO 2 /H 2 mixtures. Highly active and stable Ru/γ-Al 2 O 3 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 CO 2 methanation, goes along with a flattening of the Ru nanoparticles and the formation of highly basic hydroxylated alumina sites. We propose an activated modification of the metal-support interactions (MSIs) as origin of the increased activity, caused by reactive modification of the Al 2 O 3 surface in the reductive atmosphere and increased thermal mobility of the Ru nanoparticles, allowing their transfer to modified surface sites. We suggest this as general approach for the modification of alumina-supported noble metal catalysts in reactions involving reducing atmospheres.