Low-temperature catalytic oxidation of toluene over Mn–Co–O/Ce0.65Zr0.35O2 mixed oxide catalysts

Abstract

Ce0.65Zr0.35O2 was prepared by co-precipitation method and a series of Mn1-yCoy/Ce0.65Zr0.35O2 catalysts with different Mn/Co molar ratio were synthesized via the co-impregnation method. These catalysts were applied for gaseous toluene oxidation, which showed that the catalytic activity was significantly improved by the addition of Mn and Co. In particular, Mn–Co(1:1)/Ce0.65Zr0.35O2 with Mn/Co molar ratio of 1:1 displayed the best result with the lowest complete conversion temperature of 242 °C under a GHSV of 12,000 h−1. The as-prepared catalysts were characterized by X-ray diffraction, H2 temperature-programmed reduction, N2 adsorption–desorption, X-ray photoelectron spectroscopy and O2 temperature-programmed desorption. These characteristics revealed that the coexistence of Mn and Co could enhance the redox property and generate more surface adsorbed oxygen, thereby improving the performance of the catalysts for toluene low-temperature oxidation. The Mn–Co(1:1)/Ce0.65Zr0.35O2 exhibited the best catalytic activity and high stability. The excellent catalytic activity of the Mn–Co(1:1)/Ce0.65Zr0.35O2 could be ascribed to a greater amount of surface adsorbed oxygen species and Mn4+ on the catalyst surface.