Progress of ammonia selective catalytic oxidation research and performance improvement strategy

Selective catalytic oxidation of ammonia (NH3-SCO), as the main technology for treating ammonia leaks from diesel engines, converts excess NH3 into harmless N2 and H2O through catalysts. Catalysts follow different reaction mechanisms during the reaction process, which can be broadly classified into four types according to the reaction pathways and characteristic intermediates. The current research hotspots of ammonia oxidation catalysts are to improve the ammonia oxidation rate in the low temperature region of the catalyst and widen the catalytic temperature window, to improve the N2 selectivity of the catalyst and reduce the side reaction products, and to improve the catalyst stability, including cycling stability and hydrothermal stability. There are many factors affecting the three catalyst properties, and this paper summarizes the effective strategies to improve the performance of acidity, redox performance, and hydrothermal stability such as modification/doping, selection of support, creation of novel nanostructures and crystal planes, and optimization of preparation methods, so as to expect inspiration for the design and future research of NH3-SCO catalysts.