Catalytic Removal of Benzene at Mild Temperature over Manganese Oxide Catalysts

Series of MnOx catalysts were synthesized through oxalate route and calcined at facile temperatures. Characterizations through XRD, N2-adsorption/desorption, HRTEM, C6H6-TPD, O2-TPD, XPS, and H2-TPR revealed that MnOx calcined at 250 °C (N250) with a main crystal phase of Mn2O3 showed micro-mesopores and largest specific surface area, and therefore had a high adsorption capacity of C6H6. N250 also presented better oxygen mobility, rich surface adsorbed oxygen species (Oads), and proper ratio of surface Mn4+/Mn3+. The starting temperature of H2-TPR of N250 was the lowest among the obtained MnOx samples. As a result, N250 exhibited the lowest T90 value of 191 °C in C6H6 thermal catalytic oxidation (WHSV 60,000 mL gcat.−1 h−1, initial C6H6 concentration 190 ppm) among all the catalysts, and this T90 value is lower than those reported in many research. At last, a potential reaction pathway was proposed according to the results of in-situ FTIR measurement.