In-depth exploration of NH3-SCR over metal-based zeolite catalyst improvement research at low-temperature: Catalytic activity, sulfur/phosphorus resistance and hydrothermal stability

Ammonia selective catalytic reduction (NH3-SCR) is the mainstream technology for controlling nitrogen oxide (NOx) emissions. However, the widespread application of zeolite catalysts faces multiple challenges: susceptibility to sulfur/phosphoru (S/P)-poisoning, narrow reaction temperature windows, and poor hydrothermal stability. This paper systematically reviews recent advances in metal zeolite catalysts, focusing on their low-temperature reaction mechanisms. Analysis addresses the aforementioned issues from two dimensions: (1) For Fe- and Cu-based monometallic catalysts, this study investigates the influence of active sites, framework Al, metal species migration, and acidity modification strategies on catalyst performance. (2) For composite metal catalysts, this study elucidates intermetallic electron transfer and synergistic effects within different frameworks, emphasizing the refinement of low-temperature reaction mechanisms and performance. It also supplements key techniques such as X-ray absorption spectroscopy (XAS), X-ray diffraction (XRD), and brunauer emmett teller (BET) for SCR applications. The aim is to provide a theoretical foundation and research pathway for developing novel, highly efficient NH3-SCR catalysts, while proposing future research directions.