Exhaust gas after-treatment device for vehicle engine

Abstract

An exhaust gas after-treatment device for an engine comprises a first catalyst configured to decrease an amount of a hydrocarbon contained in an exhaust gas; and a second catalyst disposed in sequence with the first catalyst, the second catalyst configured to reduce an amount of a nitrogen oxide contained in the exhaust gas, wherein the exhaust gas after-treatment device is disposed on an exhaust passage of the engine and the second catalyst is prepared by engine bench aging.

What is claimed is: 
     
         1 . An exhaust gas after-treatment device for an engine comprising:
 a first catalyst configured to decrease an amount of a hydrocarbon contained in an exhaust gas; and   a second catalyst disposed in sequence with the first catalyst, the second catalyst configured to reduce an amount of a nitrogen oxide contained in the exhaust gas,   wherein the exhaust gas after-treatment device is disposed on an exhaust passage of the engine and   the second catalyst is prepared by engine bench aging.   
     
     
         2 . The exhaust gas after-treatment device of  claim 1 , wherein the first catalyst is prepared by aging in an electric furnace. 
     
     
         3 . The exhaust gas after-treatment device of  claim 1 , wherein the first catalyst is a palladium catalyst. 
     
     
         4 . The exhaust gas after-treatment device of  claim 1 , wherein the second catalyst is a rhodium catalyst. 
     
     
         5 . The exhaust gas after-treatment device of  claim 2 , wherein the first catalyst is aged for a preset time period at a temperature of 1250° C. 
     
     
         6 . The exhaust gas after-treatment device of  claim 5 , wherein the preset time period is between 25 and 150 hours. 
     
     
         7 . The exhaust gas after-treatment device of  claim 2 , wherein the first catalyst is aged for a preset time period at a temperature between 1000° C. and 1100° C. and the electric furnace further comprises nitrogen. 
     
     
         8 . The exhaust gas after-treatment device of  claim 7 , wherein the preset time period is between 25 and 100 hours. 
     
     
         9 . The exhaust gas after-treatment device of  claim 1 , wherein the second catalyst is aged by engine bench aging for a preset time period with an air/fuel ratio of lambda 0.95 to 1.1 and a temperature of 1000° C. to 1100° C. 
     
     
         10 . The exhaust gas after-treatment device of  claim 9 , wherein the preset time period is between 25 and 100 hours.