锰基低温NH₃-SCR脱硝催化剂的研究概述

Selective catalytic reduction with Ammonia (NH₃-SCR), which has received widespread attention by utilizing NH₃ as reducing agents to achieve high-efficiency conversion of NO_x. Although commercial V₂O₅-WO₃(MoO₃)/TiO₂ catalysts have been came into service, however, in order to meet higher and more complex practical application requirements, especially the exploitation of low-temperature denitration catalysts still stimulate the development of novel SCR catalysts. Among varied metal oxide catalysts, manganese oxide exhibits great potential in low-temperature NH₃-SCR reactions, which can be ascribed to its variable cation valence, unstable surface oxygen and excellent redox performance. However, the efficiency of current manganese-based denitration catalysts is still limited by the conversion rate of NO_x, N₂ selectivity, operating temperature window, and deactivation substances such as SO₂ and H₂O, alkaline/alkaline earth metals, and heavy metals. Therefore, in recent years, researchers have focused on improving the working efficiency of manganese-based low-temperature catalysts in the above four aspects, and have achieved fruitful results. On the premise of making full use of the advantages of manganese oxide, the work efficiency of manganese-based catalysts at low temperatures is significantly improved. In addition to studying the efficiency of single manganese oxide, researchers have used a variety of synthetic methods such as hydrothermal, water bath, and immersion methods to modify manganese oxides with transition metals and rare earth metals. The multi-element metal oxide formed after compounding and doping modification can greatly improve the ability to address the above four aspects. Moreover, by studying diffe-rent substrate materials supporting manganese oxide, such as TiO₂, Al₂O₃, carbon materials and inorganic non-metallic minerals, the efficiency and stability of the catalyst can also be improved. And through in-depth exploration of the relevant reaction mechanisms of manganese-based low-temperature catalysts, including "Langmuir-Hinshelwood" "Eley-Rideal" and "Fast SCR" reaction mechanism, which can provide theoretical guidance for improving the efficiency of the catalyst. This review mainly summarizes the efforts made by researchers in recent years to improve the efficiency of manganese-based low-temperature catalysts, and the challenges of manganese-based catalysts, the regulation of manganese oxides and related reaction mechanisms are introduced respectively. Furthermore, we pay attention to the problems that confronting the current state-of-the-art manganese-based low-temperature catalysts and put forward corresponding prospects. It is expected to provide a reference for the preparation of high-efficiency, stable and environment-friendly low-temperature denitration catalysts in the future.