Catalytic removal NO by CO over LaNi0.5M0.5O3 (M = Co, Mn, Cu) perovskite oxide catalysts: Tune surface chemical composition to improve N2 selectivity

Catalytic removal of NO by CO has been studied over a series of LaNi0.5M0.5O3 (M = Co, Mn, Cu) perovskite oxide catalysts were synthetized via an improved sol-gel method. The effects of M-doped on physicochemical properties of LaNiO3 were systemic characterized by XRD, BET, SEM, ICP-AES, XPS, H-2-TPR and O-2-TPD techniques. The possible catalytic mechanism for NO + CO model reaction was also tentatively proposed with the help of the in situ DRIFTS technique. The M-doped samples remained pure perovskite structure and exhibited modified activity, among which the LaNi0.5M0.5O3 possessed optimized catalytic performance, especially superior N-2 selectivity. It is confirmed that the amorphous CuO highly dispersed on Cu-doped defective perovskite oxide, the reduction of Cu2+ to Cu+ is vital for the chemisorption of CO, a large amount of oxygen vacancies accelerated the dissociation of NO and N2O. Hence, adsorbed CO can fast react with N and O at lower temperature, afterwards N2O was converted to N-2 fleetly, leading the improvement of activity/selectivity toward NO + CO reaction.