| Using catalysts to.purify automotive exhaust gas has attracted more and more attention. It is generally accepted that the most important factor in these catalysts should be determined by the oxygen storage materials,which have a direct relationship with its catalytic performance.The influence of different preparation methods and the Ce/Zr ratio,as well as the aging temperatures on the oxygen storage capacity(OSC) of CeO2-ZrO2 solid solution and other metals doped ones were studied in detail.Oxygen pulse technique,X-ray Diffractometer(XRD) and Brunauer Enmet Teller(BET) surface area analysis methods were used to characterize OSC,textual property and surface area of the materials.Some meaningful results were got as follows:(1)Compared with co-precipitation and hydrothermal method,the Ce0.5Zr0.5O2 sample prepared by sol-gel method have the higher OSC,especially when the sample was prepared with ethanol as coagulant.It had the highest OSC of 601μmol/g under 350℃.But the samples prepared by co-precipitation and hydrothermal method showed especially lower OSC. The ratio of Ce/Zr influences the OSC.When the ratio of Ce/Zr is 6:4,the sample had the best OSC.Though the samples calcined at 600℃had the higher OSC,after calcinated at higher temperature,the OSC decreased apparently.(2)As to the Fe doped Ce-Zr sample,when Ce-Zr-Fe solid solution was formed,no matter it was substitutional or interstitial solid solutions,the OSC of the sample erthanced a little with the increasing amout of Fe content;However when there were the co-existence of Ce-Zr-Fe solid solution and Fe2O3 crystal in the sample,the OSC increased obviously,and the sample remained its higher OSC even after being aged at 900℃,OSC was 2640μmol/g highly.(3) Ce-Zr-Fe solid solution itself,Cu loaded Ce-Zr solid solution and Ce-Zr-Fe solid solution sample,were tested for its catalytic performance for simultaneous removal of NO,CO,and hydrocarbon.It indicated that activity of Cu modified Ce-Zr-Fe solid solution showed the highest catalytic activity.While the Cu loaded Ce-Zr solid solution sample had the lowest activity. |
