【作者】 史忠华；

【导师】 陈耀强；

【作者基本信息】 四川大学 ， 物理化学， 2006， 博士

【摘要】 本文对密偶型汽车尾气净化催化剂的关键性材料――耐高温高比表面积载体的制备规律及性能进行了深入的研究。在制备出新型耐高温高比表面积氧化铝载体的基础上,系统的研究了密偶型汽车尾气净化催化剂的制备方法、催化剂的组成、贵金属的种类、含量以及助剂的种类与催化剂性能的关系。同时研究了催化剂的温度特性、空燃比特性和抗老化性能,研制出了高性能的密偶型汽车尾气净化催化剂。在此基础上研究了密偶催化剂的单一反应,得出各个组分对HC转化性能的影响规律,并且初步探索了NO抑制烷烃转化的机理。在耐高温高比表面积载体材料的研制过程中,发现以碳酸铵为沉淀剂的氧化铝载体比以氨水为沉淀剂的载体具有更大的比表面积、孔容、平均孔径和更好的高温稳定性。这是由于以碳酸铵做沉淀剂得到的氧化铝前驱物是片钠铝石所致。在沉淀方法上使用并流法得到的载体性能优于滴加法制备的载体。沉淀的pH控制在8.5左右为宜。在沉淀的过程中加入高聚物能明显改善载体材料的织构性能及抗老化性能,发现聚合物分子量大小适中、添加量适当时效果最佳。助剂La的添加能显著提载体的比表面积和高温稳定性能。La的添加量以3wt%为最佳。用喷雾干燥法可得到颗粒均匀,大小适中,适宜用于催化剂的制备的耐高温高比表面材料。所研制的耐高温高比表面积氧化铝载体La-Al2O3经过1000℃老化后,比表面积为167.6更多还原

【Abstract】 In the thesis the key alumina support material of close coupled catalyst was studied in detail, which was high-temperature-resistant and had high surface area. The relation was systematically investigated among preparation methods, the content of noble metals, the promoter and the catalytic performance of the close coupled catalyst. At last, a close coupled catalyst was successfully prepared with high performance. The single reaction of the close coupled catalyst was studied. The possible mechanism was found for the influence of NO on propane oxidation.In the process of preparation of support, ammonium carbonate was found to be a better precipitant than ammonium hydroxide. The alumina prepared with ammonium carbonate showed higher surface area, larger pore volume, mean pore diameter and higher thermal stability because its precursor was ammonium aluminum carbonate hydroxyl (AACH). The precipitating pH should be controlled on 8.5. When pH was below 8.5, there would produce amorphous hydroxide. But above 8.5, bayerite would be produced. Proper polymer would increase the surface area and mean pore diameter of alumina. La promoter could add the thermal stability of alumina. The content of La should be moderate. Spraying dry method could increase the identity of the alumina pellet. The La-Al2O3 prepared with all controlled condition had a surface area of 167.6 m2/g,更多还原