Exhaust aftertreatment system for compression-ignition engines

Abstract

An internal combustion engine configured to operate in a compression-ignition combustion mode includes an exhaust aftertreatment system. The exhaust aftertreatment system includes a catalyst device fluidly coupled upstream of an ammonia-selective catalytic reduction device. The, catalyst device includes first, second, and third elements fluidly coupled in series. The first element includes a three-way catalytic element, the second element includes a NOx adsorber, and the third element includes an oxidation catalytic element.

1 . An exhaust aftertreatment system for an internal combustion engine configured to operate in a compression-ignition combustion mode, comprising:
 a catalyst device fluidly coupled upstream of an ammonia-selective catalytic reduction device, said catalyst device comprising first, second, and third elements fluidly coupled in series;   said first element comprising a three-way catalytic element;   said second element comprising a NOx adsorber; and   said third element comprising an oxidation catalytic element.   
     
     
         2 . The exhaust aftertreatment system of  claim 1 , wherein the three-way catalytic element comprises a substrate coated with a washcoat including Pd/Al2O3. 
     
     
         3 . The exhaust aftertreatment system of  claim 1 , wherein the NOx adsorber comprises a substrate coated with a washcoat including LaMnO2 and BaO. 
     
     
         4 . The exhaust aftertreatment system of  claim 1 , wherein the oxidation catalytic element comprises a substrate coated with a washcoat including Rh/CeO2 and Al2O3. 
     
     
         5 . An exhaust aftertreatment system for a compression-ignition internal combustion engine, the exhaust gas aftertreatment system consisting essentially of:
 a device comprising first, second, and third elements fluidly coupled in series, wherein the first element comprises a three-way catalytic element, the second element comprises a NOx adsorber, and the third element comprises an oxidation catalytic element;   an ammonia-selective catalytic reduction device; and   a particulate filter;   the device located fluidly upstream of the ammonia-selective catalytic reduction device located fluidly upstream of the particulate filter.   
     
     
         6 . The exhaust aftertreatment system of  claim 5 , wherein the three-way catalytic element comprises a substrate coated with a washcoat including Pd/Al2O3. 
     
     
         7 . The exhaust aftertreatment system of  claim 5 , wherein the NOx adsorber comprises a substrate coated with a washcoat including LaMnO2 and BaO. 
     
     
         8 . The exhaust aftertreatment system of  claim 5 , wherein the oxidation catalytic element comprises a substrate coated with a washcoat including Rh/CeO2 and Al2O3. 
     
     
         9 . An apparatus, including:
 said internal combustion engine configured to operate in a compression-ignition combustion mode fluidly coupled to a passive NH3-SCR exhaust aftertreatment system;   said passive NH3-SCR exhaust aftertreatment system comprising a catalyst device fluidly coupled upstream of an ammonia-selective catalytic reduction device fluidly coupled upstream of a particulate filter;   said catalyst device comprising first, second, and third elements fluidly coupled in series;   said first element comprising a three-way catalytic element;   said second element comprising a NOx adsorber; and   said third element comprising an oxidation catalytic element.   
     
     
         10 . The apparatus of  claim 9 , wherein the three-way catalytic element comprises a substrate coated with a washcoat including Pd/Al2O3. 
     
     
         11 . The apparatus of  claim 9 , wherein the NOx adsorber comprises a substrate coated with a washcoat including LaMnO2 and BaO. 
     
     
         12 . The apparatus of  claim 9 , wherein the oxidation catalytic element comprises a substrate coated with a washcoat including Rh/CeO2 and Al2O3.