Barrier effect of SiO2 shell over hollow CeO2/CuO@SiO2 catalysts for broadening temperature window of total CO conversion

摘要

The hollow inverse CeO2/CuO@SiO2 catalysts with different Ce/Cu mass ratios were synthesized by the two-step hydrothermal and incipient wetness impregnation methods, and characterized by multitechnique characterizations, such as SEM, TEM, XRD, H-2-TPR, XPS and N-2 adsorption-desorption techniques. It is found that the hollow shell is composed of CuO and SiO2, and CeO2 nanoparticles are coated on the surface of CuO@SiO2 support. And the CeO2/CuO@SiO2 catalyst with the Ce/Cu mass ratios of 1:1 denoted as 1CeO(2)/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 SiO2 shell effectively prevents the reduction of CuO species, which broadens temperature window of CO total conversion and enhances CO2 selectivity above 155 degrees C over the 1CeO(2)/CuO@SiO2 catalyst in comparison with the CuO-CeO2 and CeO2-CuO catalysts. (C) 2019 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.