| 摘要 |
PURPOSE:To enable the stable preparation of a monolithic catalyst of which the noble metal supporting amount becomes much toward the central part thereof, by a method wherein a catalytically active metal is thinly supported by a monolithic carrier while the peripheral part of said carrier is coated with a coating material and a catalytically active noble metal is further supported by the treated carrier. CONSTITUTION:After a catalytically active noble metal is thinly supported by a monolithic carrier, an inner cylinder 2 with a small diameter and an outer cylinder 3 with a diameter almost equal to that of the carrier 1 are concentrically provided to the upper end surface of the vertically hold carrier 1 and a polyvinyl alcohol solution being a coating agent is flowed into the interior of the carrier 1 from the gap between the inner cylinder 2 and the outer cylinder 3. Subsequently, the solution of the carrier 1 is blown off by an air stream and dried under heating to coat the peripheral part of the carrier 1 with the coating material. Succeedingly, this carrier 1 is immersed in a catalytically active metal-containing solution and the impregnated one is taken out to be baked. According to circumstances, while range for coating the carrier 1 with the coating agent is increased after baking, the aforementioned catalytically active noble metal supporting process is repeated each time. |
