| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide an exhaust gas purification catalyst having a high NOx adsorption property in a region containing excessive oxygen, good reactivity with released reduction substances such as NOx, HC and CO, and excellent in durability as well as NOx purification performance. <P>SOLUTION: An exhaust gas purification catalyst is produced by coating a catalyst layer containing Pt, Pd, Rh and NOx adsorption material on a refractory inorganic carrier, wherein Pt is contained in a higher concentration as closer to the surface of the catalyst layer; 10 to 100% of the total amount of Pt is contained within a range of depth of 0.1 mm from the surface of the catalyst layer; the catalyst layer is an exhaust gas purification catalyst consisting of an upper layer containing Pt and Rh, and a lower layer containing Pt and Pd; and the amount of Pt in the upper layer is 30 to 80% of the total amount of Pt, Rh in the catalyst layer is supported by alumina at a rate of 0.1 to 2.0 g per catalyst 1 L; each of materials constituting the catalyst layer has an average particle size (median size) of 4 μm or less; and a catalyst layer containing NOx adsorption material and noble metal is coated on a refractory inorganic carrier by an impregnation method. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
