Study On The Ceria-zirconia Solid Solution-based Catalyst For Vehicle Exhaust Gas Purification

It is essential to innovate the catalyst for purification of vehicle exhaust gas because air pollution is even serious with increase of vehicles. In this paper, ceria-zirconia solid solution with larger specific surface area, well thermal stability and oxygen storage capacity were prepared to act as support for such purifying catalysts. This work will be benefit to develop a novel catalyst for exhaust gas treatment.Ceria-zirconia solid solution was respectively synthesized via solid state reaction, coprecipitation and hydrothermal methods. The effect of different factors on the structure and performance of solid solution was systematically investigated. The results showed that ceria-zirconia solid solution synthesized by solid state reaction exhibited more surface defective sites and lower stability. It resulted in the lower surface area and wider pore diameter distribution after cacination. While the samples prepared by hydrothermal method bear higher thermal stability, lager surface area and narrow pore diameter distribution. The more surface defective sites contribute the better oxygen storage capacity. It means that the solid solution prepared by solid state reaction possesses the optimum oxygen storage capacity among the three preparation methods, and simultaneously bear the lowest reduction temperature. On the contrary, the samples synthesized by hydrothermal method showed poor oxygen storage capacity and higher reduced temperature. The performance of the ceria-zirconia solid solution synthesized by coprecipitation was in the middle of the others. The research showed that Taguchi design was reasonable method to investigate optimal synthesis conditions. The main effect factor was also obtained using this design method. In order to improve the thermal stability of ceria-zirconia solid solution, transitional metal oxides was introduced. Pr was good stabilizer to improve the structure of solid solution.The catalysts for exhaust gas treatment were prepared by impregnation method. The results showed that the catalyst supported by ceria-zirconia solid solution synthesized via coprecipitation method possessed lower ignition temperature, via hydrothermal method bear the highest conversion. While the solid solution prepared with solid state reaction exhibited the poor catalytic performance compared with others. For the conversion of CO, the ignition temperature was increased with increase of Pd supported. For the conversion of CH4, the rule was opposite. Moreover, the investigation showed that there is intimate relationship between the structure of solid solution and catalyst performance. The support with larger specific surface area, uniform pore diameter distribution showed better catalytic reaction performance...