Precious metal-support interaction in automotive exhaust catalysts

Precious metal-support interaction plays an important role in thermal stability and catalytic performance of the automotive exhaust catalysts. The support is not only a cartier for active compotmds in catalysts but also can improve the dispersion of precious metals and suppress the sintering of precious metals at high temperature; meanwhile, noble metals can also enhance the redox performance and oxygen storage capacity of support. The mechanism of metal-support interactions mainly includes electronic interaction, formation of alloy and inward diffusion of metal into the support or covered by support. The form and degree of precious metal-sup- port interaction depend on many factors, including the content of precious metal, the species of support and metal, and preparation methods. The research results about strong metal-support interaction （SMSI） gave a theory support for developing a kind of new cata- lyst with excellent performance. This paper reviewed the interaction phenomenon and mechanism of precious metals （Pt, Pd, Rh） and support such as A1203, CeO2, and CeO2-based oxides in automotive exhaust catalysts. The factors that affect SMSI and the catalysts developed by SMSI were also discussed.

汽车尾气净化催化剂的现状与发展

介绍并展望了汽车催化剂组成(包括主催化剂、助催化剂、稳定剂、扩表涂层、载体等)的现状和发展趋势,以及 与汽车催化剂相关的技术,如电子学与化学的耦合用于排放控制、冷启动排放的对策及贫燃条件下的催化技术等。认为以贵 金属为主体的三效催化剂继续占有优势,贵金属的回收循环使用将变得越来越重要。

贵金属—稀土复合型催化剂工作性能的研究

制备了净化车辆尾气的贵金属—稀土复合型催化剂,对该催化剂的活性进行了测试;利用所制备的催化剂在摩托车上进行了性能研究。试验结果表明,催化剂可以快速起燃,但催化活性与催化剂温度之间存在一定时间的滞后现象。将所制备的催化剂在多款车型的摩托车上进行了应用,结果表明,能使排放达到欧Ⅱ标准,而且通过了10000km的道路耐久性试验。

铂/钡基NO_x存储还原催化材料研究进展

从中国汽车排放法规升级、中国汽车行业发展需求、催化材料的国内外研究基础及应用集成技术研究进展、后处理系统成本控制四个角度,分析了铂/钡基NO_x存储还原(NSR)催化材料在我国汽车尾气污染防治行业应用存在的机遇与挑战。

稀土—过渡金属—贵金属型汽车尾气净化催化剂的研究成果及产业化

在微反色谱装置上研究了负载型Pt,Pt-RE,Pd-Ni-La-Ce,Pd-Co-La-Ce,Pt-Pd-Rh-RE等催化剂的烃转化及一氧化碳氧化的活性和稳定性。用TPR,TPD等方法研究了铂与稀土、载体的相互作用,铂与钯、铑之间的相互作用,研究了催化剂的制备工艺。对稀土—过渡金属—贵金属型催化剂进行了汽车怠速实验,并在国家指定的权威单位进行了二八工况评价试验。结果表明,所研制的三效催化剂达到欧洲Ⅱ标准。