Synthesis Of Transitional Metal Doped CZ And Study On Their Properties

Oxygen storage materials are an important part in the three-way catalyst, and singleceria-zirconium solid solution has not yet satisfied the requirement for three-way catalyst atimproving catalytic activity and heat-resistant. Ceria-zirconium solid solution doped bytransition metals was reported by many researches，however, the systematic research oninteractions between the ceria-zirconium solid solution, the doped oxides and active componentsis still relatively less.In this dissertation, Ce0.5Zr0.5O2solid solution doped by copper with different content andpreparing method, doped by Fe, Ni, Co, Zn were prepared. Then the influence of these factorswas studied on physical and chemical capability of the ceria-zirconium solid solution was furtherinvestigated. The products were characterized by BET, XRD, H2-TPR and O2-TPDmeasurements. These doped ceria-zirconium solid solutions were applied to CO oxidationreactions and the influential factor of performance was discussed based on the results ofevaluation for reacting activity. The catalysts were prepared by supporting loaded0.5%Pd onthese doped ceria-zirconium solid solutions. The influence on the performance of Pd/CZcatalysts with different Cu content and these dopants such as Fe, Ni, Co, Zn were studied. Therelationship between phase composition, texture property, redox property of the catalysts and thecatalytic activity were also studied.The results indicated that among the samples of Ce0.5Zr0.5O2solid solution doped withdifferent content of copper, Cu was well dispersed on the surface of ceria-zirconium solidsolution or entered the ceria-zirconium solid solution, the doped content had no obvious effect onthe texture property, and when the doped amount was7wt%(i.e. in CZC0.15), it has a goodperformance on reduction and CO oxidative activity. Their performances on the phasecomposition, redox property and the OSC were different with different doped methods. Thesample synthesized by co-precipitation had a higher surface area and reduction performance thanthat of the samples by the other methods. These datas of CO oxidative activity testified the result.When Pd/CZ was doped by Cu mental, its catalytic activity in the oxidation reaction declined,the reason may be that copper exerting a kind of blocking effect on the most active Pd–CZcontacts, which reduced the catalytic active sites. While Pd/CZ was doped by Fe, Ni, Co, Znmental, the doped mental blocked active Pd–CZ contacts, which reduced the catalytic active sites.For the sample doped by Fe, the surface area increased, improving the dispersion of active components, and Fe and ceria-zirconia solid solution produced a strong interaction, resulting inmore oxygen active sites, promoting the catalytic activity in CO oxidation reaction. However,when Pd/CZ was doped by Ni, Co, Zn mental, the surface area reduced, which reduced thedispersion of the active metal, the above two factors reduced the catalytic active sites, so thecatalytic activity declined.