Ru改性的铁基钙钛矿体系的催化性能研究

为研究Ru改性的铁基钙钛矿体系的催化性能,用溶胶-凝胶法分别制备了不同x、y、n值的La1-xCexFe1-y-nCoy RunO3系列化合物,在模拟条件下,以起燃温度和气体转化效率为90%时的温度为评价指标测定了HC、CO及NOx的三效催化活性.研究表明:改性催化剂具有更高的催化活性和抗老化能力;Ru的引入可大幅度提高催化活性,且催化活性与Ru离子的掺杂量成正比;La0.8Ce0.2Fe0.7Co0.2Ru0.1O3样品的催化性能较佳,起燃温度分别可达到HC 295℃、CO 280℃,NOx 280℃.     

多元复合铁基非贵金属催化剂的性能研究

用溶胶-凝胶法制备一系列不同取值的多元复合铁基钙钛矿化合物.在模拟条件下,以起燃温度和气体转化效率90%时的温度为评价指标测定HC、CO及NOx的三效催化活性.结果表明:改性催化剂具有更高的催化活性和抗老化能力;一定取代量的非贵金属引入可较大幅度提高催化活性,且催化活性与掺杂少量贵金属Ru离子的相似,可能是多元调变使B位离子的变价能力提高,同时使表面氧脱附能力增强的结果.因结构中有氧缺陷结构的催化活性中心SrFeO2.83,SrFeO3-λ晶相存在,La0.6Ce0.2Sr0.2Fe0.4Co0.2Cu0.2Mn0.2O3样品的三效催化性能较佳,起燃温度分别可达到CO 360℃,NOx380℃,HC 520℃.     

Three-Way Catalytic Converter Modelling with Detailed Kinetics and Washcoat Diffusion

A single channel model for a three-way catalytic converter based on mechanistic kinetics is developed. The axi-symmetrical transient model uses one dimension for the gas phase and two for the solid phase. Light-off curves for cold start operation are used to show the capability of the model and the influence of diffusion in the washcoat on the light-off performance. It is shown that the concentration of reacting species and adsorbed intermediates undergo large changes during the light-off operation. The model is used to show the importance of dynamic adsorption during light-off. Under cold conditions a fresh catalyst can adsorb large amounts of material, which affects the light-off performance. Typical global kinetic models do not explicitly include the adsorption steps. Under normal driving conditions with the feed composition oscillating about the stoichiometric point, the concentration profiles in the washcoat can develop some surprising patterns.     

稀土在汽车尾气三元净化催化剂中的应用现状与展望

稀土在我国的汽车排放污染控制方面有着广泛的应用。介绍了稀土作为三元催化剂的助催化剂、稳定剂、贵金属和载体的表面分散剂以及稀土复合氧化物作为催化剂的组分等方面的研究现状,并对稀土在汽车尾气净化催化剂中的研究和开发提出了一些设想和建议。