Catalytic converter having tri precious metal catalysts

摘要

In general, the present invention includes a catalytic converter including a substrate having a trimetal catalyst system thereon. The trimetal catalyst system includes a double coat system in which Pt and Rh are together on one layer and Pd is separate on a second layer. The invention also includes three discoveries. (1) It has been found that there is a conversion efficiency improvement when Pt and Rh are on the outer layer of a dual layer system while Pd is on the inner layer. (2) It has been found that there is a conversion efficiency improvement when the masses of the two layers are in a mass ratio of about 3:1 to about 1.25:l and preferably 2:1. That is, the inner layer contains twice the washcoat mass as the outer layer. (3) It has been found that the dual coat system can be produced using one calcining step.