Barrier effect of SiO2shell over hollow CeO2/CuO@SiO2catalysts for broadening temperature window of total CO conversion

The hollow inverse CeO2/CuO@SiO2catalysts with different Ce/Cu mass ratios were synthesized by the two-step hydrothermal and incipient wetness impregnation methods, and characterized by multi-technique characterizations, such as SEM, TEM, XRD, H2-TPR, XPS and N2adsorption-desorption techniques. It is found that the hollow shell is composed of CuO and SiO2, and CeO2nanoparticles are coated on the surface of CuO@SiO2support. And the CeO2/CuO@SiO2catalyst with the Ce/Cu mass ratios of 1:1 denoted as 1CeO2/CuO@SiO2, which possesses a maximum amount of highly dispersed copper species and medium-sized CuO as well as the highest concentration of oxygen vacancies, exhibits the highest catalytic activity and widest full CO conversion window. The barrier effect of the SiO2shell effectively prevents the reduction of CuO species, which broadens temperature window of CO total conversion and enhances CO2selectivity above 155 °C over the 1CeO2/CuO@SiO2catalyst in comparison with the CuOCeO2and CeO2CuO catalysts.