Reactivity of methanol over copper supported on well-shaped CeO2: a TPD-DRIFTS study

TPD-DRIFTS experiments upon methanol adsorption over copper (5 wt%) supported on well-shaped ceria (polyhedra, rods and cubes) have been performed for the first time. Support morphology influences the type of methoxy and formate adsorbed species; in polyhedron and rod-shaped catalysts, linear methoxy and formate are the predominant species, while in cube-shaped catalyst, bridged species dominate. In the catalysts, desorption of H-2 and CO2 increases significantly indicating that besides dehydrogenation of adsorbed methoxy, oxidation of adsorbed formate species is taking place. Heterogeneity of surface sites (copper, ceria and copper/ceria interface), surface defects and acid-base properties may account for the differences in the desorption profiles and reactivities of the adsorbed species over the three copper-ceria catalysts.