Exhaust gas catalyst and method of manufacturing same

Abstract

The present invention involves an exhaust gas catalyst and method of manufacturing same. The invention provides for a cost-effective material which lowers the cold-start emissions from the exhaust of vehicles. The invention is a passive system which accelerates the light-off temperature of catalyst in a cost-effective fashion. The invention includes a method of manufacturing an exhaust gas catalyst capable of lowering cold-start emissions including the steps of providing an oxide mixture having praseodymium and cerium, doping about 0-10% weight zirconium and about 0-10% weight yttrium to the oxide mixture, adding about 0-2% weight metal including palladium, platinum, or rhodium to the oxide mixture, mixing gamma aluminum to the oxide mixture for washcoating and washcoating the oxide mixture onto a monolithic substrate.

What is claimed is:  
     
         1 . A method of manufacturing an exhaust gas catalyst capable of lowering cold-start emissions, the method comprising: 
 providing an oxide mixture of praseodymium and cerium;    doping the oxide mixture with 0-10 wt % zirconium and 0%-10 wt % yttrium;    doping the oxide mixture with 0-2 wt % precious metal;    mixing gamma alumina to the oxide mixture for washcoating; and    washcoating the mixture onto a monolithic substrate.    
     
     
         2 . The method of  claim 1  wherein the oxide mixture has praseodymium and cerium in substantially equal molar content.  
     
     
         3 . The method of  claim 1  wherein the step of doping further comprises doping about 0-2 wt % zirconium and about 0-2 wt % yttrium to the oxide mixture.  
     
     
         4 . The method of  claim 1  wherein the step of doping further comprises doping about 0.1-1.5 wt % precious metal to the oxide mixture.  
     
     
         5 . The method of  claim 4  wherein the step of doping the precious metal occurs immediately after the step of doping the zirconium and yttrium to the oxide material.  
     
     
         6 . The method of  claim 1  wherein gamma alumina is mixed with the oxide mixture at a ratio of 0.1-1 mole of gamma alumina to the oxide mixture.  
     
     
         7 . The method of claim, wherein the precious metal is selected from the group consisting of platinum, rhodium, palladium, and mixtures thereof.  
     
     
         8 . An exhaust gas catalyst supported on a monolithic substrate, the catalyst capable of lowering cold-start emissions, the catalyst comprising: 
 an oxide mixture washcoated on the monolithic substrate, the oxide mixture having substantially equal molar content of praseodymium and cerium, about 0-10 wt % zirconium and about 0-10 wt % yttrium, and about 0-2 wt % precious metal.    
     
     
         9 . A method of manufacturing an exhaust gas catalyst capable of lowering cold-start emissions, the method comprising: 
 providing an oxide mixture of praseodymium and cerium;    doping the oxide mixture with 0-10 wt % zirconium, 0%-10 wt % yttrium, and 0-2 wt % precious metal;    mixing gamma alumina to the oxide mixture for washcoating; and    washcoating the mixture onto a monolithic substrate, whereby providing praseodymium increases oxygen storage capacity of the catalyst and decreases a required amount of the precious metal doped to the oxide mixture of the catalyst.