【作者】 谭宇新；

【导师】 王乐夫；

【作者基本信息】 华南理工大学 ， 工业催化， 2000， 博士

【摘要】 在国际上，具有比动力输出高、燃料利用率高、更经济、CO和HC污染小等优势的贫燃汽油发动机、柴油发动机的设计和应用呈不断上升的趋势。传统的汽车尾气净化三效催化剂在贫燃条件下是失效的。目前正在研究的某些用于贫燃条件下汽车尾气净化的分子筛催化剂，虽然活性、选择性高，但在高湿热状况下容易因分子筛的晶体结构被破坏而导致失活。一种新型的磷酸硅铝分子筛SAPO-34因具有孔结构适宜、酸性可调、耐湿热性好等优良特性而有希望成为实用的分子筛催化剂载体。本研究针对现有分子筛催化剂的不足之处，合成了SAPO-34分子筛并将其作为载体研制了用于贫燃条件下汽车尾气净化的Ag-SAPO-34、Cu-SAPO-34分子筛系列催化剂以及Ag-SAPO-34+CeO₂、Cu-SAPO-34+CeO₂、Ce／Cu／SAPO34双功能系列催化剂，着重解决了以下三个关键的问题： 对影响合成磷酸硅铝分子筛SAPO—34的晶化温度和时间，模板剂，原料铝源和硅源，原料硅含量等工艺参数进行了系统的研究和优化，解决了合成SAPO—34的晶化过程中很容易伴生SAPO-5分子筛的问题。用水热法以优化的工艺合成了高纯度、高结晶度的SAPO-34作为贫燃条件下汽车尾气净化催化剂的新型载体，解决了以往分子筛载体耐湿热稳定性差的致命弱点。 用离子交换法制备了Ag-SAPO-34和Cu-SAPO-34分子筛催化剂，并对其制备工艺、活性、湿热稳定性、反应机理进行了全面系统的研究，研制出具有低温活性好，而且耐湿热稳定性好的Ag-SAPO-34分子筛催化剂。该催化剂上NO转化成N₂的转化率在336℃左右达到最大值73.6％。经过高温水热处理后，催化剂的活性仅降低2.3～5.5个百分点。还研制出具有活性高、高温活性好、温度操作范围广以及耐湿热稳定性好等优良特性的Cu-SAPO-34分子筛催化剂。该催化剂上NO转化成N₂的转化率在430℃左右达到最大值75.4％。经过高温水热处理后，催化剂的活性仅降低2～5个百分点左右。在两种催化剂上，NO在B酸活性中心氧化为NO₂都是整个C₃H₆选择性还原NO反应中的关键的第一步。然后C₃H₆对NO₂的还原分别在一价Ag⁺的分子筛骨架Ag，二价Cu²⁺的分子筛骨架Cu活性中心进行，生成N₂、H₂O、COx。 在对Ag-SAPO-34和Cu-SAPO-34分子筛催化剂全面系统研究的基础上，根据双功能催化剂的概念设计、筛选了Ag-SAPO-34+CeO₂、Cu-SAPO-34+CeO₂、更多还原

【Abstract】 The design and application of lean-burn petrol engine and diesel engine are rising now in the world for the advantages of higher output power, more effective burning, more economy and less emission of CO and HC. The traditional three-way catalyst is ineffective under lean-burn conditions. Though the lean-burn automobile exhaust molecular sieves catalysts being studied now are active and selective, they are very easy to be inactive in the presence of vapor at high temperature for the destroy of crystal structure. A new type of silicoaluminophosphates SAPO-34 is very suitable as support of automobile exhaust catalysts under lean-burn conditions due to its suitable structure of pore, adjustable acidity and good hydrothermal stability. According to the disadvantages of molecular sieve catalysts above, SAPO-34 has been synthesized first and then Ion-Exchanged Ag-SAPO-34 and Cu-SAPO-34 catalysts as well as biflinctional catalysts of Ag-SAPO-34 + CeO₂, Cu-SAPO-34 + CeO₂ and Ce/Cu/SAPO34 have been prepared to aim to solve the following three problems:Based on the study and optimum of synthesized technology parameters, such as crystallizing temperature, crystallizing time, template, the source of Si and Al, the content of Si and etc., high purity and crystalline silicoaluminophosphates SAPO-34 has been synthesized successfully, and there is no by-product SAPO-5. The synthetic SAPO-34 is proved much hydrothermal stable and very suitable as support of automobile exhaust catalysts under lean-burn conditions.The activities, preparation technology, hydrothermal stability and reaction mechanism of Ion-Exchanged Ag-SAPO-34 and Cu-SAPO-34 catalysts have been studied in details. The Ag-SAPO-34 catalyst which is active at low temperature and much hydrothermal stable has been prepared, on which the highest conversion of NO to N₂ is 73.6% at the temperature of 336℃. And the conversion only decreases by 2.3-5.5 percents after being treated hydrothermally. The Cu-SAPO-34 catalyst which has high activity, wide operating temperature range and excellent hydrothermal stability has been prepared too, on which the highest conversion of NO to N₂ is 75.4% at the temperature of 430℃. And the conversion only decrease by 2-5 percents after being treated更多还原