| The precusous and aluminas prepared by ammonium hydroxide and ammonium carbonate as precipitating agents respectively were characterized by BET, XRD and TG/DTA. The aluminas prepared by ammonium carbonate showed larger surface area, pore volume and average pore diameter and higher thermal stability than those formed by ammonium hydroxide. So the two kinds of supports of catalyst YSZ-Al2O3 and La-Al2O3 were prepared by ammonium carbonate as precipitating agent. They both showed high thermal stability and appropriate pore distribute. Their surface area are 147.3 and 156.6 m2?g-1 respectively after aged at 1000℃. The activity and stability of the close-coupled catalysts supported by different supports were studied. The results showed that the supports have little effect on the reaction performance of the fresh catalysts, but much effect on the stability of the catalysts. In addition, stability and conversion of CO were improved after oxygen storage material added. Reaction performance of the different catalysts, which comprise different noble metals as active composition was studied. The Pt-Rh catalyst showed best activity, high stability and wide rang of air/fuel ratio. The activity of Pd catalyst and Pd-Pt-Rh catalyst were worse than Pt-Rh catalyst but better than Pd-Pt catalyst. The Pd catalyst showed narrow range of air/fuel ratio and lowest conversion of CO. Moreover, the effect of several kinds of additives on reaction performance of catalysts was studied. It was discovered that added Zr the stability of catalyst was improved greatly and added Sr the activity of fresh catalyst was improved greatly. The activity and stability of the catalyst added Zr and W were all improved greatly.
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