Advancements in rare earth mullite oxides (AMn2O5) for catalytic oxidation: Structure, activity and design strategies

The development of rare earth catalysts is expected to reduce the dependence on noble metal catalysts in mobile and stationary sources. The AMn₂O₅ mullite oxide is a category of rare earth metal oxides for the catalytic oxidation of environmental pollutants, in which the A-site cations are the rare earth cations. The coexistence of the diverse Mn ions and the exposed Mn-Mn dimers in AMn₂O₅ mullite oxides contribute to the excellent catalytic performance for various catalytic reactions. Herein, the crystal structure and the identification of lattice oxygen of AMn₂O₅ mullite oxides have been discussed. Meanwhile, a comprehensive understanding of the activity and the thermal stability of AMn₂O₅ mullite oxides has been investigated. As a group of rare earth catalysts, the representing modification strategies with their advantages have been summarized to guide the rational design of next-generation mullite oxide catalysts. To gain a deeper understanding of AMn₂O₅ mullite oxides as heterogeneous catalysts, we have reviewed the publications in catalytic purification of vehicle exhaust and catalytic oxidation of volatile organic compounds, accompanied by the exploration of corresponding reaction mechanisms and the analysis of applied modification strategies. Furthermore, the perspective research direction of AMn₂O₅ mullite oxide catalysts has been outlined to inspire more valuable research work.