Recent advances and perspectives in the resistance of SO2 and H2O of cerium-based catalysts for NOx selective catalytic reduction with ammonia

NOx is one of the most severe air contaminants, which mainly comes from fixed sources and has a tremendous negative impact on public health and regional air quality. The treatment of NOx has become an important issue. Among numerous NOx emission control technologies, selective catalytic reduction using ammonia as the reducing agent (NH3-SCR) is regarded as the most effective and mature technique with 40 years of development. Currently, commercial NH3-SCR catalysts are mainly vanadium-based catalysts; however, V2O5 is identified as a biotoxic species. A cerium-based catalyst is a kind of environment friendly catalyst for NH3-SCR. However, exhaust gas usually contains a small amount of SO2 and H2O vapor under actual conditions, inhibiting the NH3-SCR reaction with cerium-based catalysts. Therefore, improving the resistance of SO2 and H2O of cerium-based catalysts has become a research hotspot in recent years. This review presents a unified discussion of the significant work published in the field of the resistance of SO2 and H2O of cerium-based catalysts for NH3-SCR. It emphasizes the reaction mechanism and aspects of cerium-based catalysts at different levels: metal modification, preparation methods, and structures. The discussion is then extended to the essential conclusions from cerium-based catalyst modification and recommendations for future directions to develop a catalytic system that will degenerate NOx over non-noble metal catalysts with high resistance of SO2 and H2O.

Automated summary

NOx is a severe air pollutant, and NH3-SCR technology is regarded as an effective way to treat it. Cerium-based catalysts are environmentally friendly, but improvements in resistance to withstand actual exhaust conditions are needed.