Copper/Nickel/Cobalt modified molybdenum-tungsten-titanium dioxide-based catalysts for multi-pollution control of nitrogen oxide, benzene, and toluene: Enhanced redox capacity and mechanism study.

Previous studies have indicated the potential of monometallic-modified TiO catalysts in controlling nitrogen oxide (NO) and volatile organic compounds (VOCs) in coal-fired flue gas. Unfortunately, increasing selective catalytic reduction (SCR) activity under complicated coal-fired flue gas status is tricky. In this study, modified Co-MoWTiO catalysts with multiple active sites were synthesized using the wet impregnation method, which exhibited excellent multi-pollution control ability of NO, benzene and toluene under low oxygen and high SO concentrations. The modification of Mo and Co achieved high dispersion and electron transfer. The interaction between W/W and Co/Co promoted gas-phase O adsorption on the catalyst surface, forming of reactive oxygen species (O). Density functional theory (DFT) calculations informed that the doping of Co effectively enhanced the NH and O adsorption capacity of the catalyst, and Co possessed the maximum adsorption energy for NH and O. Possible pathways of multi-pollution control of NO, CH, and CH were speculated. NH/NH on the Lewis/Bronsted acid site is reacted with intermediates of NO (e.g., NO, nitrite, nitrate) via the Langmuir-Hinshelwood and Eley-Rideal mechanism. The introduction of NO and NH did not disrupt the oxidation pathways of benzene and toluene. Following the Mars-van Krevelen mechanism, CH and CH were progressively mineralized by O into CO and HO.