| 摘要 |
PURPOSE:To obtain a catalyst for purification of the exhaust gases of automobiles of improved performance wherein the difference in the thickness of layers of both Pt and Rh depositing liquids is in a specific range by depositing these liquids at varying pH values on a carrier. CONSTITUTION:Ammonia or the like is added to a Pt compd. soln. to control said soln. to alkalinity of 7.5-8.5pH, and this soln. is impregnated with a carrier of alumina or the like, whereby Pt is deposited thereon. Nitric acid or the like is added to an Rh compd. soln. to control the soln. to acidity of 5.5- 6.5pH. Said carrier deposited with the Pt is put in this aq. soln., whereby it is impregnated with said soln. and is deposited with Rh. After the carrier deposited with the Pt and the Rh in this way is dried, it is calcined in a hydrogen atmosphere. This yields the catalyst wherein the difference in the thicknesses of the Pt layer and the Rh layer is <=100mu, which provides sufficient performance as a three-element catalyst and has improved durability. |
