Diesel Exhaust Treatment System Catalyst Monitoring

Abstract

Diesel exhaust treatment articles, systems and methods are disclosed. According to one or more embodiments, an oxygen storage component is utilized and degradation of the oxygen storage component is correlated with degradation of the hydrocarbon conversion efficiency of a catalyst in a diesel engine system.

1 . A diesel exhaust system comprising:
 a diesel catalyst selected from a diesel oxidation catalyst and a catalyzed soot filter;   a first lambda sensor located upstream of the diesel catalyst and a second lambda sensor located downstream from the diesel catalyst; and   an oxygen storage component located between the sensors.   
   
   
       2 . The diesel exhaust system of  claim 1  wherein the oxygen storage component is located downstream from the from the diesel catalyst. 
   
   
       3 . The diesel exhaust system of  claim 2  wherein the system includes a diesel oxidation catalyst. 
   
   
       4 . The diesel exhaust system of  claim 3  wherein the diesel oxidation catalyst includes a precious metal component on a substrate and an oxygen storage component on a substrate. 
   
   
       5 . The diesel exhaust system of  claim 4  wherein the precious metal component and the oxygen storage component are on the same substrate. 
   
   
       6 . The diesel exhaust system of  claim 5  wherein the oxygen storage component includes ceria in close contact with the precious metal component. 
   
   
       7 . The diesel exhaust system of  claim 5  wherein the oxygen storage component and precious metal component are separated. 
   
   
       8 . The diesel exhaust system of  claim 7  wherein the oxygen storage component and precious metal component are on separate substrates. 
   
   
       9 . The diesel exhaust system of  claim 7  wherein the oxygen storage component and precious metal component are contained in separate layers on the same substrate. 
   
   
       10 . The diesel exhaust system of  claim 1  wherein the first lambda sensor and second lambda sensor are in communication with an on board diagnostic system. 
   
   
       11 . The diesel exhaust system of  claim 1  wherein the first lambda sensor and second lambda sensor are selected from the group consisting of UEGO and HEGO sensors. 
   
   
       12 . A method of monitoring the hydrocarbon conversion efficiency of a catalyst in a diesel engine system comprising:
 passing an exhaust gas stream of a diesel engine through a diesel catalyst selected from a diesel oxidation catalyst and a catalyzed soot filter, the diesel catalyst capable of converting hydrocarbons by oxidation;   measuring degradation of an oxygen storage component located in the path of the exhaust gas stream; and   correlating the degradation of the oxygen storage catalyst with a decrease in hydrocarbon conversion efficiency.   
   
   
       13 . The method of  claim 12  further comprising activating an alarm when the hydrocarbon conversion efficiency decreases below a pre-selected value.