Abstract: A reconstruction strategy has been developed to synthesize Cu-SAPO-34 with a wide crystallization phase region, high solid yield, and tunable Si and Cu contents. Cu-rich SAPO-34 was prepared from a Cu-amine complex, which acted as a precursor and Cu source for the reconstruction synthesis. The role of the Cu-amine complex as a template was restricted, which allowed easier control over the Cu and Si contents than in the previously reported "one-pot" synthesis method. Characterization of the material revealed that the Si(4Al) coordination environment dominates the synthesized Cu-SAPO-34 catalysts. High-temperature hydrothermal treatment increased the isolated Cu²⁺ content slightly, and the acid sites in the low-silica catalyst are more resistant to hydrothermal treatment than those of the existing catalysts. The obtained materials, especially the low-silica Cu-SAPO-34 sample, exhibit excellent catalytic activity and hydrothermal stability for the selective catalytic reduction of NO_x by NH₃ (NH₃-SCR). In addition, the influence of the catalyst acidity on the NH₃-SCR reaction was also investigated and is discussed. The high synthetic efficiency and outstanding catalytic performance make Cu-SAPO-34 synthesized by the reconstruction method a promising catalyst for the NH₃-SCR process.

Key words: Cu-SAPO-34, Hydrothermal synthesis, NH₃-SCR, Hydrothermal stability, Crystallization