Mechanism and sites requirement for CO hydrogenation to CH3OH over Cu/CeO2 catalysts

This study investigated the Cu-CeO 2 interactions for CO hydrogenation to methanol by applying rate measurements, chemical titration/desorption, together with in-situ/operando spectroscopy techniques under realistic reaction conditions. Ce components were enriched in the surface region of Cu/CeO 2 catalysts while Ce 3+ and Ce 4+ atoms co-existed during CO hydrogenation. The ratio of Ce 3+ to Cu 0 in the surface region of catalysts increased linearly with the Ce content. The turnover rates of CH 3 OH formation increased as a single-valued function of the ratio, irrespective to the individual contact extent between Cu and CeO 2 clusters or Ce content in the Cu/CeO 2 catalysts, indicating that the Cu 0 -Ce 3+ sites pair acts as active sites for CO hydrogenation to methanol over Ce-CeO 2 samples. This study also unraveled that formyl and formate species, as reactive surface intermediates, were co-adsorbed on the Cu 0 -Ce 3+ sites, and their hydrogenation routes occurred concurrently for CH 3 OH formation during CO-H 2 reactions.