贫燃条件下汽车尾气净化催化剂Ag-SAPO-34湿热稳定性的研究

Study on Hydrothermal Stability of Automobile Exhaust Gas Ag-SAPO-34 Catalyst under Lean-burn Condition

为解决贫燃条件下汽车尾气净化催化剂湿热稳定性差的问题,采用离子交换法把Ag离子交换到耐湿热性好的磷酸硅铝分子筛SAPO—34上,制备了有良好湿热稳定性的Ag—SAPO—34分子筛催化剂。研究结果表明:该催化剂经600℃、800℃高温水热处理8h后,活性分别平均降低2.3％和5.5％。水热处理初始4h时,催化剂活性下降2～5个百分点。随着水热处理时间增加到8～12h,催化剂活性的下降幅度逐渐减少至1～3个百分点,并趋向于稳定。同时,SEN、XRD表征测试结果表明,催化剂的表面形貌和骨架晶格结构在热处理和水热处理前后没有发生大的变化,这是催化剂耐湿热稳定性好的根本原因。

To improve the catalyst hydrothermal stability under lean-burn condition, Ag-SAPO-34 catalyst has been prepared in Ion-exchanged way. The catalytic activities of Ag-SAPO-34 catalyst only decreased by 2.3% and 5.5% after being hydrothermal treated 8 hours at 600℃ and 800℃. And at the first 4 hours, it decreased by the range of 2% to 5% and then 1% to 3% after 8 hours. The results of SEM and XRD showed that the good hydrothermal stability of Ag-SAPO-34 catalyst is due to its surface and crystalline structure still unchanged after being thermal treated under high temperature.