Study Of Preparation Of Cerium-Zirconium Solid Solution And Its Properties Modification

Three-way catalyst?TWC?is the key to solve the increasingly serious problem of vehicle emissions.However,the excessive fluctuation of the air/fuel ratio?A/F?of the engine exhaust reduces the efficiency of three-way catalysts for catalyzing HC,CO,and NO_x.As an oxygen storage material,the addition of cerium-zirconium solid solution to the three-way catalyst can adjust the air-fuel ratio of the catalytic environment and increase the efficiency of the catalystIn this paper,the high specific surface area cerium-zirconium solid solution was synthesized by liquid-phase chemical co-precipitation method,BET,XRD,H₂-TPR,TEM,SEM and other characterization results were used to determine the optimal preparation process.The results showed that the reaction temperature was 40?,the reaction time was 1-2h,the aging temperature and time were 90-100? and 8-12h,respectively.and the heating rate was set to be gradually calcined.The sample has the best high temperature stability and reduction performance.The cerium-zirconium solid solution was prepared by the multi-step coprecipitation method.Properties of the cerium-zirconium solid solution were studied and the optimum preparation process of the co-precipitation method was determined.The results show that the improved multi-step co-precipitation method can achieve better doping effect.The specific surface area of the obtained cerium-zirconium solid solution is the largest in the step-by-step precipitation ratio of salt solution 0.20/0.4,0.05/0.35,and the range of NH₂O₂:NCe³⁺ is 2-5.The maximum specific surface area of fresh samples is 143.13m2·g-1,and the maximum specific surface area of aging samples is 41.69m2·g-1.Modified cerium-zirconium solid solution was modified by organic solvent and doped with La/Y.The results show that the precursor modification can enhance the high temperature stability of the solid solution and make the pore size distribution more uniform.Multi-step co-precipitation method was used to modify the surface,The maximum specific surface area of fresh samples is 188.87m2·g-1,and the maximum specific surface area of aging samples is 62.52m2·g-1 and has good oxygen storage capacity and low temperature reduction performance.