Effect of CeO2 addition on the structure and activity of RuO2/γ-Al2O3 catalyst

RuO2/γ-Al2O3 and RuO2-CeO2/γ-Al2O3 catalysts, prepared by impregnation of γ-Al2O3 with aqueous solution containing Ru and Ce were used to study the influence of CeO2 on the structure and activity of RuO2/γ-Al2O3 catalyst in catalytic wet air oxidation (CWAO) of phenol. The surface properties of two catalysts were measured by BET, SEM, XRD and XPS. Slight aggregates of Ru particles were observed on the surface of RuO2/γ-Al2O3 catalyst, while a better dispersion of Ru particles was detected in the presence of CeO2 on the surface of RuO2/γ-Al2O3 catalyst. The chemical state of Ru and O was investigated. The results show that the addition of CeO2 affects the chemical state of Ru and O elements and promotes the increase of the chemisorbed oxygen contents on the catalyst surface. Moreover, the removal of phenol with RuO2-CeO2/γ-Al2O3 catalyst is more complete than with RuO2/γ-Al2O3 catalyst.