Preparation of Metal-Incorporated SAPO-34 catalysts and their Catalytic Performance in Selective Catalytic Reduction of Nitric Oxide

Abstract Metal-incorporated SAPO-34 catalysts were prepared by one-step hydrothermal method. Effects of various parameters including the types of metal ions, Cu2+ sources, structure directing agents (SDAs), hydrothermal temperature and time on catalyst activity of the metal-incorporated SAPO-34 catalysts were investigated. Three types of metal-incorporated SAPO-34 catalysts (Cu/SAPO-34, Fe/SAPO-34 and Mn/SAPO-34) were successfully obtained. Compared with Fe/SAPO-34 and Mn/SAPO-34 catalysts, Cu/SAPO-34 catalyst revealed complete cubic-like microstructure, wide active temperature window and high conversion rate in selective catalytic reduction (SCR) of nitric oxide. After defined Cu2+ was the favorable active site of SAPO-34 catalyst, the effects of four Cu2+ sources on SCR performance were further investigated, and found Cu2+ sources did not produce significant influence on nitric oxide conversion rates. SDAs determined the formation of Cu/SAPO-34 catalyst, and the Cu/SAPO-34 catalyst adopting tetraethylenepentamine (TEPA) as SDA could maintain higher crystal integrity and active sites, which were in favor of the SCR reaction. Moreover, hydrothermal temperature and time had great influences on the formation of Cu/SAPO-34 catalyst. When the hydrothermal temperature was higher than 150 oC and the hydrothermal time was longer than 3 days, the Cu/SAPO-34 catalyst with a cubic-like structure and high catalyst activity could be obtained.

摘要 本研究采用一步水热法制备了金属掺杂SAPO-34催化剂。考察了金属离子种类、Cu²⁺源、结构导向剂（SDAs）、水热温度及时间等多种参数对金属掺杂SAPO-34催化剂活性的影响。成功合成了三类金属掺杂SAPO-34催化剂：Cu/SAPO-34、Fe/SAPO-34与Mn/SAPO-34。相较于Fe/SAPO-34与Mn/SAPO-34催化剂，Cu/SAPO-34催化剂呈现出完整的类立方微观形貌，在一氧化氮选择性催化还原（SCR）反应中拥有更宽的活性温度窗口与更高的转化率。在明确Cu²⁺为SAPO-34催化剂的优势活性位点后，本研究进一步考察了四种Cu²⁺源对SCR性能的影响，结果表明不同Cu²⁺源对一氧化氮转化率无显著影响。结构导向剂决定了Cu/SAPO-34催化剂的形貌结构，以四亚乙基五胺（TEPA）作为结构导向剂制备的Cu/SAPO-34催化剂可保持更高的晶体完整性与活性位点，更有利于SCR反应的进行。此外，水热温度与时间对Cu/SAPO-34催化剂的形成具有显著影响：当水热温度高于150℃、水热时长超过3天时，可获得具有类立方结构与高催化活性的Cu/SAPO-34催化剂。