| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust gas purification catalyst with improved NOx trap catalytic function (adsorption, separation, cleaning, S-releasing)by bringing barium, cerium and platinum into close contact, and its production method. <P>SOLUTION: This exhaust gas purification catalyst contains porous powders carrying barium and cerium, and has a standard deviation σ of frequency distribution of intensity ratio of barium to cerium by the EPMA method measured with a scanning interval of 0.5 μm, ranging 0.1-2.5. The catalyst is produced by impregnating an aqueous solution formed by mixing at least barium with cerium in an ionized state into the porous powders without causing precipitation of barium and cerium, and baking. An aqueous solution of barium acetate and an aqueous solution of cerium acetate are used. Baking is continued at 400-700°C for one hour or longer. <P>COPYRIGHT: (C)2005,JPO&NCIPI |
