Rh/CeO2 composites prepared by combining dealloying with calcination as an efficient catalyst for CO oxidation and CH4 combustion

Abstract In this paper, a series of Rh/CeO2 catalysts with three-dimensional porous nanorod frameworks and large specific surface area were prepared by chemical dealloying Al-Ce-Rh precursor alloys and then calcining in pure O2. The effect of the Rh content and calcination temperature on CO oxidation and CH4 combustion were studied, and the results revealed that the Rh/CeO2 catalysts produced by dealloying melt-spun Al91.3Ce8Rh0.7 alloy ribbons and then calcining at 500 °C exhibited the best catalytic activity, the reaction temperatures for the complete conversion of CO and CH4 were as low as 90 and 400 °C, respectively. Furthermore, after 150 h of continuous testing at high concentrations of H2O and CO2, the nature of the catalyst was not irreversibly destroyed and could still return to its initial level of activity. This excellent catalytic activity was attributed to a portion of Rh being uniformly distributed on the CeO2 nanorod surface in the form of nanoparticles, forming strong Rh-CeO2 interfacial synergy. Another portion of Rh permeated into the CeO2 lattice, which resulted in a significant increase in the number of oxygen vacancies in CeO2, thus allowing more surface active oxygen to be adsorbed and converted from the gas phase. Moreover, the catalytic reaction could proceed even in an oxygen-free environment due to the excellent oxygen storage performance of the Rh/CeO2 catalyst.