Active sites in CO2 hydrogenation over confined VOx-Rh catalysts

Metal oxide-promoted Rh-based catalysts have been widely used for CO 2 hydrogenation, especially for the ethanol synthesis. However, this reaction usually suffers low CO 2 conversion and alcohols selectivity due to the formation of byproducts methane and CO. This paper describes an efficient vanadium oxide promoted Rh-based catalysts confined in mesopore MCM-41. The Rh-0.3VO x /MCM-41 catalyst shows superior conversion (~12%) and ethanol selectivity (~24%) for CO 2 hydrogenation. The promoting effect can be attributed to the synergism of high Rh dispersion by the confinement effect of MCM-41 and the formation of VO x -Rh interface sites. Experimental and theoretical results indicate the formation of til-CO at VO x -Rh interface sites is easily dissociated into *CH x , and then *CH x can be inserted by CO to form CH 3 CO*, followed by CH 3 CO* hydrogenation to ethanol.