In brief

Abstract

Co3O4 catalysts modified with Mn and Ti, prepared by co-precipitation method, were used for catalytic oxidation of dibromomethane (CH2Br2), a model molecule for brominated volatile organic compounds (BVOCs). Addition of Ti or Ti + Mn distorted the crystal structure and led to the formation of a Co–O–Ti solid solution. The addition of Mn further enhanced the surface acidity and redox ability of the catalysts. Co–Mn–Ti exhibited the highest activity with a T90 of approximately 234 °C and the highest selectivity to CO2 at low temperatures. Additionally, Co–Mn–Ti showed good stability for at least 30 h at 500 ppm CH2Br2, 0 or 2 vol% H2O, 0 or 500 ppm p-xylene (PX), and 10% O2 at a gas hourly space velocity of 60,000 h−1, and the final products were COx, Br2, and HBr, without the formation of other Br-containing organic byproducts. This high catalytic activity was attributed to its high specific area, high surface acidity, and strong redox property. Furthermore, the synergetic effect of Co, Mn, and Ti made it superior for CH2Br2 oxidation. A plausible reaction mechanism for CH2Br2 oxidation over Co–Mn–Ti catalysts was proposed based on the analysis of the products and in situ diffuse-reflectance infrared Fourier transform spectroscopy results.