A new approach of CeO_2 and La_2O_3 effects on the three-way catalysts containing low precious metal

• 作 者: 汪文栋 林培琰 伏义路 俞寿明 孟明 张霄鹏
• 机 构: Department of Chemical Physics , University of Science and Technology of China,Hefei,Anhui 230026,Ch
• 出 处: Chinese Journal of Chemistry
• 发表日期: 2000年05期
• 关键词: precious lanthanum apparently cerium fresh nitrate dispersed impregnation efflue

A series of three-way catalysts (TWCs),containing a small amount of precious metals (PMs,including Pt,Pd and Rh) and a large amount of promoters CeO2 and La2O3,were prepared with different precursor compounds and various doped manners.Crystal phases,dispersion of cerium and lanthanum,textural structure and thermal stability of the catalysts were investigated by XRD,XPS and pore parameters determination.The catalytic performance was studied by the measurements of CO,C3H6 and NO conversions on dependence of temperature at stoichimetric number point (S=1.00),and from S=0.75 to 1.30 at 280℃ or 340℃ for fresh or aged samples,respectively.The correlation between the catalytic performance and the characteristics of fresh and aged samples were discussed.The results show that the sample,in which CeO2 and La2O3 are doped with mixed oxide powders,possesses poor dispersion and less thermal stability,and the conversions of NO and C3H6 are apparently lower than those of the samples aged at 850℃ The main reason is

A series of three-way catalysts (TWCs), containing a small amount of precious metals (PMs, including Pt, Pd and Rh) and a large amount of promoters CeO2 and La2O3, were prepared with different precursor compounds and various doped manners. Crystal phases, dispersion of cerium and lanthanum, textural structure and thermal stability of the catalysts were investigated by XRD, XPS and pore parameters determination. The catalytic performance was studied by the measurements of CO, C3H6 and NO conversions on dependence of temperature at stoichimetric number point (S = 1.00), and from S = 0.75 to 1.30 at 280 ° C or 340 ° C for fresh or aged samples, respectively. Correlation between the catalytic performance and the characteristics of fresh and aged samples were discussed.The results show that the sample , in which CeO2 and La2O3 are doped with mixed oxide powders, possesses poor dispersion and less thermal stability, and the conversions of NO and C3H6 are apparently lower than those of the samples aged at 850 The main reason is