【作者】 郑向江；

【导师】 郭灿雄；

【作者基本信息】 北京化工大学 ， 应用化学， 2007， 硕士

【摘要】 汽车尾气污染已经成为城市大气的主要污染源之一。汽车尾气净化技术是控制汽车尾气排放的主要措施，而开发实用高效的催化剂是关键。近年来，从降低成本考虑，单钯催化剂成为三效催化剂研究热点。本论文的主要研究内容是以堇青石蜂窝陶瓷为载体，以铈锆复合氧化物为助剂，以γ-Al₂O₃为涂层，制备单钯催化剂，并采用模拟尾气评价装置对催化剂进行评价。研究了不同的助剂材料、不同钯负载方式、不同钯负载量、二次评价和高温老化处理对催化剂活性的影响。同时研究了从汽车尾气废钯催化剂回收钯的方法。通过沉淀法分别制备了γ-Al₂O₃、铈锆镧和铈锆铁锰复合氧化物的前躯体，经过焙烧得到氧化物粉体。采用XRD、BET、TPR等分析方法对粉体的进行了物性表征。结果表明，铈锆镧和铈锆铁锰复合氧化物形成单一立方相固溶体结构，适用于汽车尾气催化剂的助剂材料。以铈锆铁锰复合氧化物为助剂，采用化学镀钯法制备了不同钯负载量的催化剂。经过评价后，钯负载量为2g／L的催化剂具有最佳的催化活性。以铈锆镧复合氧化物为助剂，分别采用浸渍法和化学镀法制备单钯催化剂，并进行活性评价。结果表明，采用化学镀法制备催化剂的活性要优于浸渍法。化学镀法制备催化剂经过高温老化评价后，对CO氧化仍然有比较好的选择性。以HCl-H₂O₂体系来浸取钯，选择一定的浸取条件，浸取率可以达到97％。以二氯二胺络亚钯法从浸取液中回收海绵钯，总回收率大于96％，纯度可以达到99％。更多还原

【Abstract】 Catalytic removal technology is one of the most effective ways to eliminate the automobile exhaust emission and the development of highly active and durable catalysts is the key. In comparison with the traditional three-way catalysts containing platinum, rhodium and palladium, the Pd-only three way catlalysts have drawn more considerable interests in recent years because of their higher catalytic activities and lower cost.In this paper, Pd-only catalysts were prepared with honeycomb ceramic monolith as carriers, Ce-Zr composite oxides as additives andγ-Al₂O₃ as coatings. The activities are evaluated on simulated automobile exhaust catalytic purification equipment. The factors that effect the catalytic activities including different additives, different loading ways, different Pd mass, second evaluation and aging on high temperature have been studied. The ways of recovrery of Pd from automobile exhaust spent catalysts have been studied.The powder materials includingγ-Al₂O₃, Ce-Zr-La composite oxides, Ce-Zr-Fe-Mn complex oxides have been prepared by precipitation technique, characterized by XRD, BET, TPR and other analysis methods. The results showed that Ce-Zr-La and Ce-Zr-Fe-Mn composite oxides remained solid solution structure with cubic phase after calcinations on high temperture, and applied to additives.The catalysts with Ce-Zr-Fe-Mn composite oxides as additive and loading different Pd mass have been prepared by the electroless plating method. The catalyst with Pd mass 2g/L had the best activity. The catalysts with Ce-Zr-La composite oxides as additive with Pd loading 2g/L has been prepared by the electroless plating and traditional impregnation method. The characterization results showed that catalytic properties of the catalyst prepared by electroless plating were superior to that of the catalyst prepared by impregnation; the catalytic performance of catalyst prepared by electroless plating was decreasing after characterized twice; after the catalyst aged at 1000℃for 4h, it has had good catalytic activity of CO oxidation.Pd was leached by mixed HCl-H₂O₂ solutions with extraction rate 97%, precipitated and purificated by Pd（NH₃）Cl₂ and reduced by hydration combined amine. Pd total recovery >96%, purity>99%.更多还原