Research Progress of SCR Denitration Catalyst in NOx Exhaust Gas Treatment

Abstract

Selective Catalytic Reduction (SCR) is an effective treatment technology for NOx in exhaust. It has the advantages of high denitration efficiency and stable operation performance. However, SCR-related catalysts are prone to poisoning and the operating costs are high. The intensive researches of SCR-related catalysts are important for further industrial application. This paper focuses on the SCR reaction principle and technological processes. According to the different catalyst compositions, we introduced the research progress of noble metal catalysts, metal oxide catalysts and molecular sieve catalysts. Among them, Pt and Pd noble metal catalysts are expensive and have low selectivity, and gradually eliminated from the market; V2O5-based metal oxide catalysts are the most successful in commercial applications, but there are still disadvantages such as catalyst poisoning and unfriendly environment because of vanadium metal toxicity; Ce-based metal oxide catalysts are classified as low-temperature catalysts, it is found that the blockage of the active center is mainly avoided by changing the structure of the support, and the catalyst activity is improved by adding other transition metals. Mn-based metal oxide catalysts have excellent performance at low temperature and have been the most studied in recent years, and their selectivity and stability are mainly improved by changing the crystal form and doping with other elements. Iron-based metal oxide catalysts are environmentally friendly and low-cost, and most recent studies have focused on improving the activity of catalysts by controlling the crystal planes and morphologies. In addition, molecular sieve catalysts have attracted the attention of scholars due to the large specific surface area and the special microporous structure, and recent researches are focused on the synthesis process of molecular sieves and element doping modification to improve the thermal stability and activity of catalysts. Finally, this paper points out the possible problems of catalyst replacement, radioactive waste treatment when SCR technology is applied in the field of spent fuel reprocessing, and forecasts the future development direction of SCR-related catalysts.