Apparatus and method for regenerating a particulate filter with a non-uniformly loaded oxidation catalyst

Abstract

An apparatus for removing particulate soot from an exhaust gas of an internal combustion engine includes a catalyst and a soot particulate filter positioned downstream of the catalyst for trapping soot particles therein. Atomized fuel is injected into the catalyst. The catalyst has a non-uniform catalytic loading such that the catalyst has an upstream region having a catalytic loading of a first concentration and a downstream region having a catalytic loading of a second concentration. The first concentration is greater than the first. The catalyst catalyzes an exothermic oxidation reaction between the hydrocarbon fuel and oxygen in the exhaust gas. Heat from this exothermic oxidation reaction is transferred to the soot particulate filter thereby igniting the soot particles trapped therein. A method for regenerating a particulate filter assembly having with a catalyst having a non-uniform catalytic coating is also disclosed.

1 . An emission abatement device comprising:
 a particulate filter,   an oxidation catalyst positioned upstream from the particulate filter, the oxidation catalyst comprising a substrate including (i) an upstream region having a catalytic material loading of a first concentration, and (ii) a downstream region having a catalytic material loading of a second concentration that is less than the first concentration, and   a fuel injector configured to inject fuel into the upstream region of the oxidation catalyst.   
     
     
         2 . The emission abatement device of  claim 1 , wherein the fuel injector is a fuel atomizer configured to inject atomized fuel into the upstream region of the substrate. 
     
     
         3 . The emission abatement device of  claim 1 , wherein the substrate has a longitudinal length, and the upstream region of the substrate is less than 50% of the longitudinal length. 
     
     
         4 . The emission abatement device of  claim 3 , wherein the upstream portion of the substrate is less than 25% of the longitudinal length. 
     
     
         5 . The emission abatement device of  claim 4 , wherein the upstream portion of the substrate is less than 10% of the longitudinal length. 
     
     
         6 . The emission abatement device of  claim 1 , wherein the substrate is impregnated with a precious metal. 
     
     
         7 . The emission abatement device of  claim 6 , wherein the precious metal is platinum. 
     
     
         8 . The emission abatement device of  claim 6 , wherein the precious metal is palladium. 
     
     
         9 . An oxidation catalyst for oxidizing atomized fuel in the exhaust path of an internal combustion engine, the oxidation catalyst comprising:
 a substrate including (i) a first region having a catalytic material loading of a first concentration, and (ii) a second region having a catalytic material loading of a second concentration that is less than the first concentration.   
     
     
         10 . The oxidation catalyst of  claim 1 , wherein the substrate has a longitudinal length, and the first region of the substrate is less than 50% of the longitudinal length. 
     
     
         11 . The oxidation catalyst of  claim 10 , wherein the first portion of the substrate is less than 25% of the longitudinal length. 
     
     
         12 . The oxidation catalyst of  claim 11 , wherein the first portion of the substrate is less than 10% of the longitudinal length. 
     
     
         13 . The emission abatement device of  claim 9 , wherein the substrate is impregnated with a precious metal. 
     
     
         14 . The emission abatement device of  claim 13 , wherein the precious metal is platinum. 
     
     
         15 . The emission abatement device of  claim 13 , wherein the precious metal is palladium. 
     
     
         16 . A method of regenerating a particulate filter comprising the steps of:
 injecting fuel into a first region of an oxidation catalyst, the first region having a catalytic material loading of a first concentration,   oxidizing a first portion of the injected fuel in the first region of the oxidation catalyst,   oxidizing a second portion of the injected fuel in a second region of the oxidation catalyst, the second region having a catalytic material loading of a second concentration that is less that the first concentration, and   transferring heat generated during the oxidation steps to a particulate filter positioned downstream from the oxidation catalyst to regenerate the particulate filter.