Bifunctional catalysts V-Cu/TiO2 for selective catalytic reduction of NOx and CO oxidation under oxygen-rich conditions

Abstract

The simultaneous removal of CO and NO_x in the sintering flue gas over a single catalyst is desirable but challenging. Herein, 2 %V₂O₅–5 %CuO/TiO₂ bifunctional catalysts that efficiently catalyzed CO and NO_x at low temperatures were reported, with CO and NO_x conversions of 100 % at 200–300 °C. The synergistic effect between copper and vanadium oxides enhanced the redox and CO adsorption capacities of 2 %V₂O₅–5 %CuO/TiO₂, rendering it abundant acid sites and surface chemisorbed oxygen. The in situ DRIFTS experiments demonstrated that CO oxidation over the dual-active-sites 2 %V₂O₅–5 %CuO/TiO₂ catalyst follows the Mars-van Krevelen mechanism, while the E-R mechanism was the primary NH₃-SCR pathway. Due to the presence of dual-active-sites (i.e., separated of the V active sites for the NH₃-SCR reaction and the Cu active sites for CO oxidation), the competition adsorption of CO and NH₃ on the Cu sites was weakened, resulting in higher CO oxidation performance than the single-active-site catalysts. This work provided insights into the control of flue gas containing CO and NO_x over a single catalyst.