Promoting effect of Ru-doped Mn/TiO2 catalysts for catalytic oxidation of chlorobenzene

Abstract

Mn/TiO₂ catalysts were synthesized using a deposition–precipitation method. Ru-doped Mn/TiO₂ catalysts were prepared by an incipient-wetness impregnation method. To investigate the interaction between Ru and Mn species, the catalytic performance of Mn/TiO₂ and Ru–Mn/TiO₂ catalysts in the catalytic oxidation of chlorobenzene (CB) was evaluated. The physicochemical properties of the catalysts were characterized by XRD, HRTEM, XPS, EPR, H₂-TPR, O₂-TPD and so on. The results showed that the 0.8% Ru-10% Mn/TiO₂ catalyst exhibited the best catalytic activity with 99% CB conversion at 250 °C and showed an excellent CO₂ yield (95% at 300 °C) and stability. In comparison with the 10% Mn/TiO₂ catalyst, the T90 of the Ru–Mn/TiO₂ catalyst decreased by 60 °C, which was attributed to the interaction between Ru and Mn species at the interfaces of Ru/Mn. The Ru species increased the concentration of Mn⁴⁺ and Ru⁴⁺ and reduced the H₂ reduction temperature, which was conducive to improving the redox performance of the catalysts. Ru species were highly dispersed on the Mn/TiO₂ catalyst surfaces, forming a large number of Ru/Mn interfaces. The interaction between Ru and Mn species at the interfaces of Ru/Mn promoted the formation of oxygen vacancies and surface reactive oxygen species, thus enhancing the catalytic activity.