Preparation and Characterization of Co0.2/Ce1-xZrxO2 Catalysts and Their Catalytic Activity for Soot Combustion

A series of Ce1-xZrxO2 (x = 0, 0.2, 0.4, 0.5) solid solutions were prepared by the micropore-diffused coprecipitation method with ammonia solution as precipitation agent. Co0.2/Ce1-xZrxO2 catalysts were prepared by the ultrasound-assisted incipient-wetness impregnation method. The effect of the Ce/Zr molar ratio on the catalytic activity for soot combustion was investigated. The Co0.2/Ce1-xZrxO2 catalysts gave very high activity for soot combustion under loose contact conditions between soot and catalyst, and the catalytic activity of Co0.2/Ce0.8Zr0.2O2 catalyst was the highest for the soot combustion, whose T10, T50, T90, and SmCO2 were 316 °C, 385 °C, 413 °C, and 99.9%, respectively. Compared with when there was no catalyst, T10, T50, and T90 decreased by 136, 197, and 226 °C, respectively, and SmCO2 increased by 45.9%. This catalytic activity for soot combustion is as good as that of supported Pt catalysts, which was the best catalyst system so far reported for soot combustion under loose contact conditions. All the samples were characterized by the X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and UV-Vis diffuse reflectance spectroscopy. The results showed that nanometer Ce1-xZrxO2 solid solution supports can be prepared by the micropore-diffused coprecipitation method. The average particle size of the Ce1-xZrxO2 solid solutions was about 10 nm. Doping Zr affected the dispersion of Co over the Ce1-xZrxO2 solid solutions. The right Ce/Zr molar ratio was beneficial in enhancing the catalytic activity. Temperature-programmed reduction with hydrogen measurements showed that the Co0.2/Ce0.8Zr0.2O2 catalyst had the lowest reduction temperature (203 and 298 °C), which was in good agreement with its best catalytic activity.

摘要采用微孔扩散共沉淀法制备了不同䜕Ce/Zr䜕摩尔比的䜕Ce1-xZrxO2䜕(x䜕=䜕0,䜕0.2,䜕0.4,䜕0.5)䜕固溶体,䜕并以此为载体用超声波助分散等体积浸渍法制备了䜕Co0.2/Ce1-xZrxO2䜕催化剂,䜕考察了催化剂中䜕Ce/Zr䜕比对其催化柴油车尾气碳烟颗粒物燃烧反应性能的影响.䜕䜕结果表明,䜕在催化剂与碳烟颗粒松散接触条件下,䜕Co0.2/Ce1-xZrxO2䜕催化剂催化碳烟颗粒物燃烧的活性非常高.䜕䜕其中䜕Co0.2/Ce0.8Zr0.2O2䜕催化剂活性最高,䜕T10,䜕T50,䜕T90䜕和䜕SmCO2䜕分别为䜕316䜕䜕°C,䜕385䜕°C,䜕413䜕°C䜕和䜕99.9%.䜕䜕这与目前文献报道的松散接触条件下活性最高的担载䜕Pt䜕催化剂相近.䜕䜕应用䜕X䜕射线衍射、透射电镜、扫描电镜、紫外-可见漫反射和傅里叶变换红外光谱技术对䜕Ce1-xZrxO2䜕固溶体及䜕Co0.2/Ce1-xZrxO2䜕催化剂进行了表征.䜕䜕结果表明,䜕Ce1-xZrxO2䜕固溶体纳米级小颗粒组成䜕(平均粒径在䜕10䜕nm䜕左右).䜕䜕适量的䜕Ce/Zr䜕比有利于改善立方尖晶石型䜕Co3O4䜕在䜕Ce1-xZrxO2䜕固溶体表面的分散,䜕从而提高催化剂活性.䜕䜕程序升温还原结果表明,䜕Co0.2/Ce0.8Zr0.2O2䜕催化剂具有最优的低温还原特性䜕与它具有最高的催化活性相一致.䜕䜕䜕

Co0.2/Ce1-xZrxO2 catalysts showed very high activity for soot combustion under loose contact conditions. The right Ce/Zr molar ratio was beneficial for optimizing the dispersion of Co particles and enhancing the catalyst activity.Figure optionsDownload as PowerPoint slide