Exhaust aftertreatment system

Abstract

An apparatus for treating an exhaust gas feedstream from an internal combustion engine operating lean of stoichiometry comprises a particulate filter device comprising a porous substrate element having a hydrocarbon-selective catalytically reactive washcoat. The hydrocarbon-selective catalytically reactive washcoat comprises a silver-oxide catalytic material on an alumina-based washcoat. An injection device is operative to inject a hydrocarbon reductant upstream of the particulate filter device.

1 . An apparatus for treating an exhaust gas feedstream from an internal combustion engine, comprising: a particulate filter device comprising a porous substrate element having a hydrocarbon-selective catalytically reactive washcoat, the hydrocarbon-selective catalytically reactive washcoat comprising a silver-oxide catalytic material on an alumina-based washcoat. 
     
     
         2 . The apparatus of  claim 1 , further comprising an injection device operative to inject a hydrocarbon reductant into the exhaust gas feedstream upstream of the particulate filter device. 
     
     
         3 . The apparatus of  claim 2 , further comprising a second catalytic device fluidly connected downstream of the particulate filter device and comprising a substrate coated with copper-zeolite catalytic material on an alumina washcoat. 
     
     
         4 . The apparatus of  claim 3 , wherein the second catalytic device further includes an oxidation catalyst comprising a multi-channel ceramic monolithic substrate coated with a catalytically reactive washcoat containing at least one of platinum and palladium on an alumina washcoat. 
     
     
         5 . Apparatus, comprising:
 an internal combustion engine operative at an air/fuel ratio lean of stoichiometry and directly fluidly connected to an exhaust aftertreatment system;   the exhaust aftertreatment system comprising an oxidation catalyst upstream of a particulate filter device;   the particulate filter device including a hydrocarbon-selective catalytically reactive washcoat; and   an injection device operative to inject a hydrocarbon reductant upstream of the particulate filter device.   
     
     
         6 . The apparatus of  claim 5 , wherein the hydrocarbon-selective catalytically reactive washcoat comprises a selective catalyst reduction catalyst supported on a washcoat material. 
     
     
         7 . The apparatus of  claim 6 , wherein the selective catalyst reduction catalyst comprises a silver-oxide catalytic material. 
     
     
         8 . The apparatus of  claim 7 , wherein the washcoat material comprises an alumina-based washcoat. 
     
     
         9 . The apparatus of  claim 6 , wherein a chemically reactive material of the selective catalyst reduction catalyst comprises copper. 
     
     
         10 . The apparatus of  claim 5 , further comprising the injection device operative to inject engine fuel. 
     
     
         11 . The apparatus of  claim 5 , further comprising a second catalytic device downstream of the particulate filter device. 
     
     
         12 . The apparatus of  claim 11 , wherein the second catalytic device comprises a selective catalyst reduction device. 
     
     
         13 . The apparatus of  claim 5 , wherein the internal combustion engine comprises a compression-ignition engine. 
     
     
         14 . The apparatus of  claim 5 , wherein the internal combustion engine comprises a spark-ignition engine selectively operative at a lean air/fuel ratio. 
     
     
         15 . The apparatus of  claim 5 , further comprising a sensing device operative to monitor an element of an exhaust gas feedstream in the exhaust aftertreatment system. 
     
     
         16 . An apparatus for treating an exhaust gas feedstream from an internal combustion engine operating lean of stoichiometry, comprising:
 an oxidation catalyst upstream of a particulate filter device and an injection device operative to inject a hydrocarbon reductant into the exhaust gas feedstream therebetween; and   the particulate filter device comprising a monolithic substrate element constructed of a porous material and having a hydrocarbon-selective catalytically reactive washcoat.   
     
     
         17 . The apparatus of  claim 16 , wherein the hydrocarbon-selective catalytically reactive washcoat comprises a silver-oxide catalytic material in an alumina-based washcoat. 
     
     
         18 . The apparatus of  claim 16 , wherein the hydrocarbon-selective catalytically reactive washcoat comprises a copper-oxide catalytic material in an alumina-based washcoat.