Transformation of waste battery cathode material LiMnO into efficient ultra-low temperature NH-SCR catalyst: Proton exchange synergistic vanadium modification.

It is essential to develop the catalyst for NH-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 LiMnO, one of the waste battery cathode materials, was successfully modified into a novel high-value catalyst for ultra-low temperature NH-SCR through hydrogen ion exchange and two-dimensional vanadic oxide modification. The optimized LiMnO-0.5V-10H catalyst performed the best balance of NO conversion and N selectivity, with activity reaching 96 % at 150 °C and N selectivity exceeding 70 % at ultra-low temperature. Due to the unique three-dimensional network structural characteristics of LiMnO 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 NH on the surface of LiMnO 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 N 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 purification catalyst at ultra-low temperature.