Enhanced catalytic performance for toluene combustion via Ce-doped α-MnO2: efficient balance between toluene adsorption and activation oxidation

Abstract

Herein, a series of manganese oxide catalysts were prepared via different synthesis routes and applied in the catalytic oxidation of toluene. Compared to MnO₂-RP and MnO₂-HT, MnO₂-EG with a tetragonal cryptomelane structure (α-MnO₂) synthesized via a novel ethylene glycol (EG) reduction strategy exhibits better catalytic activity for toluene combustion. Moreover, Ce-doped MnO₂-EG (Ce–MnO₂-EG) was further prepared and characterized through XRD, XRF, N₂ adsorption–desorption, SEM, H₂-TPR, O₂-TPD and XPS techniques. It was demonstrated that the strong interaction between Ce and Mn species further regulated the microstructure and surface properties of MnO₂-EG, resulting in a smaller crystal size, significant increase in specific surface area and the creation of more oxygen vacancies as well as promoted the redox capacity and lattice oxygen mobility of the Ce–MnO₂-EG catalyst. The results of C₇H₈-TPSR further indicated that effective balance between toluene adsorption capacity and activation oxidation ability may play a key role in the catalytic combustion of toluene over the Ce–MnO₂-EG catalyst, which accelerated the conversion rate and achieved an excellent low-temperature oxidation performance (T₉₀ = 197 °C). Meanwhile, Ce–MnO₂-EG also exhibited high catalytic stability with strong water tolerance (5 and 10 vol%) in the oxidation of toluene. Therefore, this work provides a new idea for the preparation of catalysts for efficient elimination of volatile organic compounds.