Morphology effect of cerium dioxide on the catalytic performance of Ru/CeO2 catalyst for the oxidation of different CVOCs

CeO2 with different morphology of rod-shape (R-CeO2), cube-shape (C-CeO2) and octahedra-shape (O-CeO2) were synthesized as supports and impregnated with Ru to obtain Ru/CeO2 catalysts, and the performance of which in catalytic oxidation of different chlorine-containing volatile organic compounds (CVOCs) (1,2-dichloroethylene (DCE) and vinyl chloride (VC)) were investigated. Due to the stronger interaction between Ru and R-CeO2, Ru was highly dispersed on R-CeO2 and more Ru entered support lattice to form Ru-O-Ce structure, thus Ru/R-CeO2 catalyst exhibited better redox property. Ru addition enhanced the acidity of Ru/R-CeO2 and Ru/C-CeO2, while that of Ru/O-CeO2 decreased instead. The acidity mainly affected DCE catalytic activity when catalyst had sufficient redox property and chlorine resistance. Run+ content was the main factor affecting VC catalytic activity. Ru/R-CeO2 catalyst exhibited the best catalytic activity in both DCE and VC catalytic oxidation with T50 of 285 °C and 207 °C, respectively, due to its excellent redox property, acidity, and sufficient Run+. In situ DRIFTS suggested that DCE was first dissociated to VC and then oxidized to carboxylates, and the addition of Ru led to the oxidation of carboxylates to carbonyl and ultimately to complete oxidation to CO2 and H2O. Run+ was important for the oxidation of carboxylate intermediates.