Promoting low-temperature methanol production over mixed oxide supported Cu catalysts: Coupling ceria-promotion and photo-activation

Abstract

Catalytic methanol production from CO2 hydrogenation at a lower temperature is limited, predominantly constricted by sluggish reaction kinetics. In this work, a ceria-modified Cu/ZnO/Al2O3 catalyst (CuZnCe-Al) is fabricated which delivers efficient low-temperature methanol production (yield= 822 g/kgCu/h and selectivity = 94% at 225 ºC and 20 bar) under light illumination. The influence of ceria loading on the morphology/microstructure, interfacial features, and surface chemistry of a Cu/ZnO-based catalyst is systematically assessed. Incorporating ceria (≤ 10 at%) into ZnO initially forms ZnO/CeOx interface which promotes both CO2 chemisorption and the formate-pathway which favours methanol production over CO. Increasing the ceria loading beyond 10 at% invoked a Cu/CeOx-dominated structure, leading to over-stabilisation of the surface reaction species and a decreased preference for methanol. The photo-enhancement factor observed for each CuZnxCey catalysts is largely independent of the ceria loading, implying that ceria inclusion imposed little influence on the Cu-ZnO interfacial characteristics.