Research Of Strontium Doped Ceria-zirconia Solid Solution

Ceria-zirconia solid solution was widely used in the Three way catalysts (TWCs) for its higher oxygen storage capacity (OSC) to alleviate the periodic fluctuate of the A/F. As the exhaust gas composition rapidly oscillates between hydrocarbon-rich and hydrocarbon-poor mixtures, the dynamic oxygen storage capacity of ceria-zirconia solid solution is important in practice.In this paper, the evaluate condation of dynamic OSC in our home-made dynamic OSC measure instrument was first set: self-designed reactor with samller dead volume, the flow rate of reactant is no lower than 300ml/min and the reactant pulse frequencies should be no higher than 0.1Hz. The alkaline earth metal Strontium was used as dopant. Fresh samples were parpared by sol-gel method and were aged under H2O/air condition to study its thermal stability. Both fresh and aged samples were characterized on home-made dynamic OSC measure instrument and TWC measure equipment for their dynamic OSC and TWC performance. Structure analysis was also done by BET, XRD and HRTEM measurement.Results showed that: Strontium doped ceria-zirconia solid solution still kept the fluorite cubic structure of ceria-zirconia solid solution and the thermal stability of ceria-zirconia solid solution has been improved by Strontium doping.Strontium doping can improve not only the dynamic oxygen storage capacity but also the total oxygen storage capacity of ceria-zirconia solid solution; aged samples had better total oxygen storage capacity than fresh samples. Both dynamic and total oxygen storage capcitay were improved most when the doping amount is 3%.For TWC performance, fresh samples were improved by Strontium doping while aged samples were not improved and aged ceria-zirconia solid solution performed better than the fresh sample.