Enhancing NH3-SCR denitrification performance through synergistic A- and B-site effects via CeFe modification of LaMnO3

Abstract

ABO₃ type perovskite catalysts are widely used in NH₃-SCR to remove NO_x due to excellent low-temperature reduction performance. To study the synergistic effect of A and B sites on the structure, morphology and redox performance of modified perovskite catalysts (La_1-xCe_xMn_1-yFe_yO₃), LaMnO₃ perovskite catalysts were co-doped with CeFe by sol-gel method, and the crystal structure, surface chemical environment, optimal metal co-doping ratio and surface adsorption of the modified perovskite catalysts were clarified through various characterizations. In addition, through first-principles calculations, the differential charge density and binding energy of each doping system were analyzed, the relationship between the difficulty of Ce doping and the electronic population of Mn atoms and the redox ability of the catalyst was discussed, and the key bond types and their changing rules in perovskite catalytic reduction were clarified. The results showed that co-doping Ce and Fe could improve the denitrification efficiency and sulfur resistance of the catalyst. When the Fe doping ratio is 0.1, the denitrification activity is the highest. Among them, the La_0.9Ce_0.1Mn_0.9Fe_0.1O₃ catalyst showed the most favorable active acid site distribution and the best reduction performance, which was conducive to the adsorption and redox of gas molecules on the catalyst surface. At the same time, when the A and B sites were co-doped, the electron transferred mainly occurs between Ce ions and Fe ions, forming a synergistic effect and changing the covalent components between Mn-O and Fe-O bonds. This made the valence states of Mn and Fe ions more, enhanced the catalytic activity of perovskite, and promoted the redox of NO on the catalyst surface, thus providing a new idea for the redox reaction pathway of modified perovskite catalysts.