THREE-WAY CONVERSION CATALYSTS AND METHODS FOR THE PREPARATION THEREFOR

摘要

A platinum group metal three-way conversion catalyst composition containing a high temperature catalytic component and a low temperature catalytic component has each catalytic component present as separate distinct particles in the same washcoat layer. The catalyst composition is prepared from a washcoat slurry containing a high temperature catalyst support material, and a low temperature catalyst support material, each support material being of sufficiently large particle size so as to prevent each support material forming a solution or a sol with the liquid medium of the slurry. The platinum group metal or metals can be impregnated into each support material either after formation of the washcoat on a non-porous refractory, metallic or palletized substrate or before forming the washcoat slurry.