Research Progress and Prospects on Poisoning Mechanism and Anti-Poisoning Modification of Cerium-Based NH3-SCR Denitrification Catalysts.

Ammonia selective catalytic reduction (NH3-SCR) has become the mainstream core technology for denitrification of industrial sintering flue gas, owing to its high denitrification efficiency and mild reaction conditions. Cerium-based catalysts, with CeO2 as the primary component, have been identified as a promising system for replacing traditional vanadium-based and noble metal catalysts. These catalysts rely on the reversible Ce3+/Ce4+ redox cycle and exhibit favorable oxygen storage-release capacity derived from lattice oxygen migration. However, the presence of multiple impurities in industrial flue gas can lead to catalyst poisoning and restrict its industrial application. Consequently, there is an urgent need for the development of cerium-based catalysts that exhibit both high denitrification activity and excellent resistance to sulfur, heavy metal and water poisoning for the engineering application of NH3-SCR technology. The present paper undertakes a systematic analysis of the poisoning mechanisms of various pollutants on cerium-based SCR denitrification catalysts. In addition, it discusses the enhancement effects of doping modification with rare earth elements, transition metal elements and non-metallic elements on the sulfur resistance of catalysts. Furthermore, it reveals the intrinsic laws of different modification pathways in improving sulfur resistance by optimizing the electronic structure, regulating surface acidic sites and inducing the formation of oxygen vacancies. The present study provides theoretical support for the design and industrial application of anti-poisoning cerium-based catalysts.