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.
Keywords: CO2 methanation; Lewis basic sites; Metal-support interactions; operando spectroscopy; particle shape.
© 2020 The Authors. Published by Wiley-VCH GmbH.