Influence of zeolite support on the synergistic reactions between NH3-SCR and CO oxidation over Cu-based catalysts

Selective catalytic reduction of ammonia (NH₃-SCR) and CO oxidation are both common reactions used to remove NO_x and CO. However, developing a bifunctional catalyst that can efficiently catalyze both reactions simultaneously remains challenging. In this study, a series of copper-based zeolite catalysts (xCu/Beta and xCu/ZSM-5) were synthesized, and the 5Cu/Beta catalyst exhibited the best performance for the simultaneous removal of NO_x and CO, achieving conversion rates of 85 % and 100 %, respectively, at 275 °C. A series of experiments and characterizations were conducted to investigate the active sites of the catalysts. The results revealed that isolated Cu²⁺ species and CuO_x clusters serve as the main active sites for NH₃-SCR and CO oxidation, respectively. Copper-based zeolite catalysts demonstrate good low-temperature NH₃-SCR activity, which is attributed to a suitable number of weakly acidic centers and the ability to convert NO to adsorbed NO₂. Compared to Cu/ZSM-5, Cu/Beta exhibits a higher proportion of Cu⁺ species, a more uniform distribution of CuO_x clusters, and superior redox properties. This results in stronger CO adsorption and activation. This work presents a novel approach to the synergistic control of gaseous pollutants using copper-based zeolite catalysts.