镨改性铈锆氧化物固溶体的制备与表征

Synthesis and Characterization of Pr-doped Ceria-Zirconia Solid Solution

采用溶胶-凝胶法制备了不同比例的Pr掺杂铈锆氧化物固溶体Ce0.6Zr0.4-xPrxO2-y(x=0.05,0.10,0.15)。X射线衍射证实形成的固溶体为萤石型立方相结构;BET比表面积分析表明,随着Pr的掺杂量由x=0.05递增到x=0.15,在650℃焙烧的样品其比表面积由66.5m2.g-1增加到79.9m2.g-1,而未掺杂样品Ce0.6Zr0.4O2的比表面积为65.1 m2.g-1;粒度分布及透射电镜分析发现,制备的固溶体在水相中存在着团聚现象。应用在含有Pt,Rh和Pd的三效催化剂的制备。催化活性测试表明,在铈锆氧化物储氧材料中掺杂少量Pr,可降低三效催化剂对CO、C3H6和NO的起燃温度。不论是在富燃区还是在贫燃区,所有掺杂Pr的三效催化剂对各气体的催化转化率均高于未掺杂Pr的三效催化剂。

Three way catalysts （TWCs） promoters Ce0.5Zr0.4-xPrxO2-y （x= 0. 05, 0. 10, 0. 15） were prepared by sol-gel method. The XRD confirmed that the Ce0.5Zr0.4-xPrxO2-y cubic solid solution is formed, and BET surface areas analysis indicate that an increasing of the dopant Pr content from x= 0. 05 to x= 0. 15 favors an increasing of surface area from 66.5 m^2·g^-1 to 79.9 m^2·g^-1 compared to the undoped sample Ce0.50Zr0.40O2 65.1 m^2·g^-1 after calcination at 650℃. Particle size distribution and TEM showed that the solid solution particles is in the form of agglomerate in the water. 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 indicated that doping a small of Pr ions into CeO2- ZrO, solid solution can lower the ligh-off temperature of catalysts for CO, C3H4 and NO convenrsion, and all the catalysts containing Pr have higher conversion for the three pollutants conversion under oxidization and reduction condition.