| In this paper the principle of the three-way catalysts for purifying exhaust gas from automobile is introduced firstly,and then a novel preparation process of catalyst for EuropeⅢstandard is described in detail,which possesses good performance to meet emission regulation and characteristic of vehicle emission and bases on a catalyst for EuropeⅡthat had been put into market successfully by Tianjin Research and Design Institute of Chemical Industry. The improvement is to reduce ignition off temperature and increase thermal stability of three-way catalyst.First,bothγ-Al2O3 with high specific surface area and better thermal stability and rare-earth complex oxide with better store oxygen ability and thermal stability was chosen as support. Theγ-Al2O3 carrier material had specific surface area 105 m2/g in 1050℃,10hrs calcination,and still kept over 30 m2/g after calcination of 50hr in air at 1200℃.The rare-earth complex oxide material had specific surface area over 75 m2/g through modification of La,Y or Pr and the specific surface increased from less than 20 m2/g to 38 m2/g after calcination 50hr in air at 1050℃.Second,the mixture ratios and contents of noble metals of Pd,Rh,Pt were optimized and a new preparation technique of double coats and twice dispersions was used to increase performance of three-way catalyst.The evaluation results of catalysts on activity in laboratory indicated that ignition temperatures were 180～250℃for CO,190～260℃for HC and 185～258℃for NOx, operation windowλ=0.9～1.1;The evaluation results for engine in cold-start at normal temperature were that HC:0.12 g/km ,0.07g/km;CO:0.59 g/km ,0.67g/km and NOx:0.01g/km,0.01g/km,which meet EuropeⅢregulation,HC:0.2 g/km,CO:2.3 g/km and NOx:0.15 g/km; cold-start at low temperature had HC:1.1 g/km and CO:11g/km,which also meet EuropeⅢregulation,HC:1.8g/km and CO:15g/km;The span life of the catalysts evaluated by engine approached to 80000km. This research had created a good condition and foundation for commercial production EuropeⅢcatalysts,as well as the industrialization of catalysts will benefit economy and social.
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