Effect of the carrier nitrogen doping on NOx&toluene synergistic degradation over VPOTi catalysts: Structure-activity relationship and reaction mechanism

Abstract

Herein, a series of nitrogen-doped TiO₂ carriers were synthesized using urea impregnation and loaded with VPO active components to evaluate NO_x&toluene synergistic degradation. Carrier nitrogen doping improved the conversion rates of NO_x and toluene, and the complete conversion of dual pollutants was achieved on VPOTiN_0.02 catalyst at 250 ∼ 350 ℃. The doping of N atoms into the TiO₂ lattice promotes the growth of the (1 0 1) plane and increases the grain size. Structurally, nitrogen doping enriched the concentrations of oxygen vacancies and active oxygen species on the VPOTi catalyst, regulated the electron distribution around Ti atoms. The redox properties of the catalyst and the reactivity of the unit catalytic site were improved by constructing the electron enrichment region of Ti³⁺-O_v. NO_x and toluene on the catalyst followed E-R&L-H co-existence and MvK mechanisms, respectively. in NH₃-SCR and toluene catalytic oxidation. The conversion rates of NO_x and toluene may be mutually inhibited by competitive adsorption of reactants. Furthermore, carrier nitrogen doping was beneficial in regulating the stability of surface nitrate species and promoting the deep oxidation of toluene.