Transformation of waste battery cathode material LiMn₂O₄ into efficient ultra-low temperature NH₃-SCR catalyst:...

It is essential to develop the catalyst for NH₃-SCR with excellent performance at ultra-low temperature (≤150 °C), and resource recycling is another important part of environmental protection. Based on the principle of environmental friendliness, the LiMn₂O₄, one of the waste battery cathode materials, was successfully modified into a novel high-value catalyst for ultra-low temperature NH₃-SCR through hydrogen ion exchange and two-dimensional vanadic oxide modification. The optimized LiMn₂O₄-0.5V-10H catalyst performed the best balance of NO_x conversion and N₂ selectivity, with activity reaching 96 % at 150 °C and N₂ selectivity exceeding 70 % at ultra-low temperature. Due to the unique three-dimensional network structural characteristics of LiMn₂O₄ spinel, hydrogen exchange could exchange Li⁺ from the lattice and increase surface acidity; and a small amount of two-dimensional vanadic oxide loading could appropriately regulate redox ability and increase acidic sites. The in-situ DRIFTS results still showed that the L-H and E-R mechanisms coexisted during the reaction. Moreover, combining first-principles calculations and in-situ DRIFTS, the dual modification of H and V could enhance the adsorption of NH₃ on the surface of LiMn₂O₄ but weaken the adsorption of NO, and promote the decomposition of nitrites while inhibit the formation of surface nitrate species, which was the core reason for the improvement of N₂ selectivity. The modification mode in this work was simple and inexpensive, which provided a new idea for the high-value utilization of waste batteries and the design of NO_x purification catalyst at ultra-low temperature.