| 摘要 |
PROBLEM TO BE SOLVED: To provide a catalyst which has a noble metal carried in high density on the surface of a coated layer in an upper flow part and is less costly. SOLUTION: An upper lamination coated layer 3 comprising porous oxide powder and the precious metal borne previously on the porous oxide powder, is formed on the surface of the upper flow part into which an exhaust gas flows from the coated layer 2. Since the precious metal is previously borne on the porous oxide powder in the upper lamination coated layer 3, the migration of the noble metal to the coated layer 2 does not occur during forming the upper lamination coated layer 3. Thus it is possible to increase the bearing density of the noble metal on the surface of the upper flow part and consequently, upgrade the contact probability between the catalyst and the exhaust gas. |
