Catalytic performance of mesoporous Mn-Co-Ti for o-xylene degradation: Mechanistic study under practical conditions

Catalytic combustion of volatile organic compounds from industrial flue gases at low temperatures remains a challenge. Herein, we developed a mesoporous Mn-Co-Ti catalyst for o-xylene degradation by a solvothermal strategy. The optimized Mn0.1Co-TiO2 catalyst possessed a nanoflower structures with a surface area of 83.1 m2/ g and mesoporous volume of 0.1191 cm3/g. Mn-doping modulated the electronic interactions between Mn and Co, which promoted the formation of MnCo2O4.5 phase and increased Co3+ and Mn4+ content of the catalyst. The Mn0.1Co-TiO2 catalyst had an improved reduction capacity from 170 to 644 degrees C, with a maximum H2 consumption of 4.56 mmol/g. The Mn0.1Co-TiO2 catalyst achieved 50% o-xylene conversion at 193 degrees C at a GHSV of 60,000 h-1, whereas the equivalent catalyst prepared by impregnation required 315 degrees C for 50% o-xylene conversion. In the presence of NO, the generated NO2 accelerated o-xylene conversion because it promoted the generation of more Mn4+-O-Co3+ active sites and accumulation of intermediates such as maleate and acetate species. NH3 and H2O had slight inhibitory effects on o-xylene conversion, which were attenuated by abundant mesopores and redox ability of catalyst. SO2 gas caused inactive sulfates and chemical deactivation on catalyst surface, thus leading to excessive formation of benzoquinone products.