【摘要】 采用共沉淀法和溶胶凝胶法制备了不同比例的Tb掺杂铈锆固溶体。X射线衍射和拉曼光谱证实,形成的固溶体为萤石型立方相结构;X光电子能谱显示,固溶体表面Ce和Tb主要以Ce4+和Tb3+形式存在;粒度分布及透射电镜分析发现,制备的固溶体在液相中存在着严重的团聚现象;应用在含Pt、Rh和Pd(高比例Pd含量)的三效催化剂的制备。催化活性测试表明,对于新鲜催化剂,当储氧助剂的制备采用共沉淀法时,随Tb掺杂量的增加,相应的掺杂催化剂对CO、C3H6和NO的起燃温度下降,以含摩尔分数为15%的Tb掺杂固溶体的催化剂起燃温度降低程度接近,分别为18、21和27℃;而采用溶胶凝胶法时,不同掺杂量催化剂对各气体的起燃温度降低程度接近。2种方法比较,溶胶凝胶法掺杂改性的催化剂起燃温度较低。经900℃老化2h后,以含摩尔分数为5%的Tb掺杂的催化剂耐热性能最好,各气体的起燃温度稍有下降。更多还原

【Abstract】 The promoters Ce_0.6Zr_0.4-xTb_xO_2-y of three-way catalysts（TWCs） were prepared by coprecipitation and sol-gel methods. The XRD and Raman spectra confirm that the Ce_0.6Zr_0.4-xTb_xO_2-y cubic solid solution is formed, and the XPS analysis indicates that the valences of Ce and Tb are maily in the forms of Ce⁴⁺ and Tb³⁺ on the surface of samples. The particle size distribution and TEM show that the solid solution particles are in the form of agglomerate in the liquid. The catalytic performance was also measured for the fully formulated Pt, Rh and Pd TWCs（high ratio of Pd） containing this kind of promoters. The results indicate that the introduction of Tb ions into CeO₂-ZrO₂ solid solution lowers the ligh-off temperature of fresh TWCs. Among TWCs （containing） the promoters which prepared via coprecipitation method, the sample containing 15% Tb exhibits the lowest ligh-off temperature, that is, 18 ℃, 21 ℃ and 27 ℃ for CO, C₃H₆ and NO_x conversion, while for those containing the promoters prepared by sol-gel method, the ligh-off temperature does not depend on Tb content, the sol-gel method is better than the coprecipitation method. For the aged samples which have been calcined at 900 ℃ for 2 h, the optimum Tb content is 5%.更多还原