Exhaust Articles for Internal Combustion Engines

Abstract

Provided is a base metal undercoat containing catalyst and an exhaust article containing the catalyst. The catalyst contains a base metal undercoat with an oxygen storage component, and at least one catalytic layer. Also provided are methods for preparing the catalyst and methods for monitoring the oxygen storage capacity of an exhaust article containing the catalyst.

1 . An exhaust article, comprising a catalyst, an upstream EGO sensor and a downstream EGO sensor; 
 wherein the catalyst comprises: 
 a base metal undercoat comprising an oxygen storage component having a concentration that provides a predetermined oxygen storage capacity; and  
 at least one catalytic layer;  
   wherein the predetermined oxygen storage capacity correlates with a TWC performance of the catalyst.    
   
   
       2 . The exhaust article of  claim 1 , further comprising a gasoline engine having an exhaust outlet leading to the catalyst.  
   
   
       3 . The exhaust article of  claim 1 , wherein the base metal undercoat is disposed on a carrier and the at least one catalytic layer is disposed on the base metal undercoat opposite the carrier.  
   
   
       4 . The exhaust article of  claim 3 , wherein the oxygen storage component is selected from the group consisting of ceria, praesodymia, and mixtures thereof.  
   
   
       5 . The exhaust article of  claim 4 , wherein the oxygen storage component is ceria.  
   
   
       6 . The exhaust article of  claim 5 , wherein the oxygen storage component comprises at least 10% by weight of the base metal undercoat.  
   
   
       7 . The exhaust article of  claim 5 , wherein the oxygen storage component comprises at least 20% by weight of the base metal undercoat.  
   
   
       8 . The exhaust article of  claim 3 , wherein the oxygen storage component is a ceria-zirconia composite.  
   
   
       9 . The exhaust article of  claim 8 , wherein there is from about 0.3 to about 1.5 g/in 3  ceria-zirconia composite in the base metal undercoat.  
   
   
       10 . The exhaust article of  claim 3 , wherein the base metal undercoat further comprises a zirconium component.  
   
   
       11 . The exhaust article of  claim 3 , wherein the base metal undercoat further comprises a nickel component or an iron component from about 1 to about 25% by weight of the base metal undercoat.  
   
   
       12 . The exhaust article of  claim 1 , wherein the catalyst comprises at least two catalytic layers on top of the base metal undercoat.  
   
   
       13 . The exhaust article of  claim 1 , wherein the catalyst comprises at least two catalytic zones.  
   
   
       14 . The exhaust article of  claim 13 , wherein the downstream EGO sensor is located between the catalytic zones.  
   
   
       15 . The exhaust article of  claim 3 , wherein the carrier is a honeycomb carrier.  
   
   
       16 . The exhaust article of  claim 1 , further comprising an upstream conduit and downstream conduit, wherein the catalyst is interposed and in train with the upstream and downstream conduits.  
   
   
       17 . The exhaust article of  claim 1 , wherein the catalyst is located in a close-coupled position.  
   
   
       18 . The exhaust article of  claim 1 , wherein the catalyst is located in an underbody position  
   
   
       19 . The exhaust article of  claim 1 , wherein the upstream and downstream EGO sensors are heated EGO sensors.  
   
   
       20 . The exhaust article of  claim 1 , wherein the base metal undercoat is substantially free of platinum group metal components.  
   
   
       21 . A method for preparing a catalyst having a base metal undercoat with an oxygen storage component, the method comprising: 
 determining a concentration of the oxygen storage component in a base metal washcoat composition that provides a predetermined oxygen storage capacity, wherein the predetermined oxygen storage capacity correlates with the TWC performance of the catalyst;    coating a carrier with the base metal washcoat composition; and    coating the base metal undercoat with at least one catalytic washcoat composition.    
   
   
       22 . A method of monitoring oxygen storage capacity of an exhaust article comprising a catalyst, an upstream HEGO sensor, and a downstream HEGO sensor, wherein the catalyst comprises a base metal undercoat and at least one catalytic layer, the method comprising: 
 passing an exhaust gas comprising unburned hydrocarbons, nitrogen oxides, oxygen and carbon monoxide through the exhaust article;    recording a frequency of voltage changes for each of the upstream and downstream HEGO sensors;    comparing the recorded frequencies; and    sending a fault signal when the recorded frequencies reach a predetermined ratio.    
   
   
       23 . The method of  claim 22 , wherein the predetermined ratio correlates with the TWC performance of the catalyst.