Synthesis of Cu-SSZ-13 with different Si/Al ratios by zeolite Y conversion and its NH3-SCR activity and hydrothermal stability

Interzeolite conversion is a convenient and low-cost method to get Cu-SSZ-13 zeolite for ammonia selective catalytic reduction (NH₃-SCR) of NO, but it is usually difficult to regulate the Si/Al ratio of the SSZ-13 in a wide range by interzeolite conversion. In this work, Cu-SSZ-13 catalysts with Si/Al ratios of 5, 10 and 20 were accurately synthesized by zeolite Y conversion with additional Si source. Specifically, the physical properties of Cu-SSZ-13 were characterized by XRD, SEM, ICP-AES and BET. The Al distribution and Cu²⁺ locations in Cu-SSZ-13 were investigated by ²⁹Si and ²⁷Al MAS NMR, DR UV–vis, H₂-TPR and EPR. The results show that Cu-SSZ-13 with Si/Al ratio of 10 shows the considerable NH₃-SCR activity and hydrothermal stability simultaneously. Moreover, different types of relationships between the reaction rate constant k and the content of α-Cu²⁺, β-Cu²⁺ species were found, indicating the diverse catalytic properties of the two active copper sites.