一步法制备Cu/SAPO-34催化剂及其低温NH₃-SCR脱硝性能研究

One-Step Synthesis of Cu/SAPO-34 Catalysts with Enhanced Low-Temperature NH₃-SCR NO_x Reduction Performance

摘要: Cu/SAPO-34催化剂优异的脱硝活性使其在NH₃-SCR反应中被广泛关注，但较低的低温(<250℃)活性严重制约了其在低温工况中的应用。针对这一瓶颈，本研究以MTO废催化剂为原料、采用一步法制备了Cu/SAPO-34催化剂，系统研究催化剂的物理结构、Cu物种类型与分布、表面酸性与低温NH₃-SCR性能。结果表明，Cu物种主要以孤立Cu²⁺和CuO形式存在，二者都可推动NH₃-SCR反应，但孤立Cu²⁺是影响低温性能的关键活性中心。丰富的酸量促进NH₃的吸附与活化；发达的孔结构在确保反应物分子快速扩散的同时，提高了Cu²⁺的利用率。相比浸渍法制备的催化剂，一步法所得催化剂表现出更高的低温脱硝活性，在150℃时其对NO_x转化率高达99.3%，且显著抑制副产物N₂O的生成。本研究创新了Cu/SAPO-34催化剂的制备方法，并阐明了催化剂的构效关系，可为高低温活性铜基催化剂的设计提供理论支撑。

Abstract: The outstanding denitrification activity of Cu/SAPO-34 catalysts has garnered widespread attention in the NH₃-SCR reaction, but their relatively low activity at temperatures below 250˚C significantly restricts their application under low-temperature conditions. To address this limitation, this study prepared Cu/SAPO-34 catalysts using spent MTO catalysts as raw materials via a one-step method, systematically investigating the catalysts’ physical structure, types and distribution of Cu species, surface acidity, and low-temperature NH₃-SCR performance. Results indicate that Cu species mainly exist as isolated Cu²⁺ and CuO, both of which can facilitate the NH₃-SCR reaction, with isolated Cu²⁺ being the key active center affecting low-temperature performance. The abundant acidity promotes NH₃ adsorption and activation, while the well-developed pore structure ensures rapid diffusion of reactants and enhances Cu²⁺ utilization. Compared with catalysts prepared by impregnation, the one-step method catalysts exhibit superior low-temperature denitrification activity, achieving an NO_x conversion of up to 99.3% at 150˚C, and significantly suppressing the formation of the by-product N₂O. This study innovatively develops a preparation method for Cu/SAPO-34 catalysts and elucidates the structure-activity relationship, providing theoretical support for the design of copper-based catalysts with high activity across both high and low temperatures.