Preparation of a transition metal-supported TiO2 catalyst and the catalytic oxidative degradation of toluene

The synthesis of supported transition metal oxides with satisfactory low-temperature catalytic performance and application potential is still a challenge for the complete degradation of VOCs. Ni-Cu-loaded TiO2 catalysts were prepared by an impregnation method. The lattice defect and oxygen vacancy concentrations of the prepared materials could be tuned by controlling the Ni/Cu molar ratio and the mass proportion of the TiO2 support. 5Ni-Cu/TiO2 exhibited the best catalytic activity and showed superior catalytic stability during complete toluene oxidation. The obtained catalysts were fully characterized by XRD, FT-IR, TEM, N2 adsorption analysis, XPS, H2-TPR, O2-TPD, TPD analysis, and XPS. The 5Ni-Cu/TiO2 catalyst had improved pore sizes and specific surface area, had more oxygen vacancies on its surface, had increased concentrations of adsorbed and lattice oxygen species, and had good redox properties; these characteristics were favorable for low-temperature catalytic performance and catalytic stability. Cyclic transformations of metal valence states between Cu+ and Cu and between Ni and Ni2+ were observed in the catalytic system. A potential catalytic reaction process based on the M-vK mechanism was proposed. This work serves as a reference for the application of supported transition metal catalysts for the degradation of VOCs. •The molar ratio between Ni and Cu has an effect on the degradation of toluene.•TiO2 significantly improved the toluene adsorption on the Ni-Cu catalyst.•Addition of TiO2 into Ni-Cu could change the valence state.•Oxygen migration and redox cycling of Ni2 + /Ni and Cu+ /Cu within the catalyst are the main reactions for the degradation of toluene.