The catalytic oxidation performance of toluene over the Ce-Mn-O catalysts: Effect of synthetic routes

Ce-Mn-Ox catalysts were synthesized by impregnation (CM-IM), co-precipitation (CM-CP), citrate sol-gel (CM-SG) and hydrothermal (CM-HT) methods. The synthesis methods exhibited a great impact on the physicochemical properties of catalysts, resulting in different catalytic activity. The catalytic oxidation activity of toluene followed the sequence: CM-HT (T50: 234 °C; T90: 246 °C) > CM-SG (T50: 242 °C; T90: 249 °C) > CM-CP (T50: 243 °C; T90: 259 °C) > CM-IM (T50: 251 °C; T90: 261 °C), which was consistent with the sequence of surface relative percentage of Cov, Ce3+, Mn3+, Oα and r values. Among them, CM-HT showed the best catalytic oxidation performance of toluene due to more structural defects, oxygen vacancies, surface adsorption oxygen, normalized conversion rate and other active species. In addition, CM-HT catalysts showed reliable water resistance and good durability, implying the potential industrial application.