Exhaust gas treatment system including a four-way catalyst and urea SCR catalyst and method of using the same
원문보기
IPC분류정보
국가/구분
United States(US) Patent
등록
국제특허분류(IPC7판)
F01N-003/00
F01N-003/10
출원번호
US-0412149
(2009-03-26)
등록번호
US-8505279
(2013-08-13)
발명자
/ 주소
Mital, Rahul
출원인 / 주소
GM Global Technology Operations LLC
대리인 / 주소
Cantor Colburn LLP
인용정보
피인용 횟수 :
1인용 특허 :
4
초록▼
The present invention is directed towards methods and systems for treatment of exhaust gas from an engine. In one embodiment, an exhaust gas treatment system for a diesel engine is provided. The system includes a urea selective catalytic reduction (U-SCR) catalyst in fluid communication with a diese
The present invention is directed towards methods and systems for treatment of exhaust gas from an engine. In one embodiment, an exhaust gas treatment system for a diesel engine is provided. The system includes a urea selective catalytic reduction (U-SCR) catalyst in fluid communication with a diesel engine to receive an exhaust gas flow therefrom. The system also includes a four-way catalyst in fluid communication with the U-SCR catalyst to receive the exhaust gas flow therefrom, the four-way catalyst comprising a lean nitrogen oxide (NOX) trap (LNT) and diesel particulate filter (DPF).
대표청구항▼
1. An exhaust gas treatment system for a diesel engine, comprising: a diesel oxidation catalyst (DOC) in fluid communication with the diesel engine to receive an exhaust gas flow therefrom, the DOC disposed in a DOC housing;a hydrocarbon injection device located between the engine and the DOC that i
1. An exhaust gas treatment system for a diesel engine, comprising: a diesel oxidation catalyst (DOC) in fluid communication with the diesel engine to receive an exhaust gas flow therefrom, the DOC disposed in a DOC housing;a hydrocarbon injection device located between the engine and the DOC that is configured to inject a hydrocarbon, CO, or H2 material, or combination thereof, into the exhaust gas flow;a urea selective catalytic reduction (U-SCR) catalyst in fluid communication with the DOC to receive the exhaust gas flow therefrom, the U-SCR catalyst disposed in a U-SCR catalyst housinga second injection device that is configured to inject urea or ammonia, or a combination thereof, into the exhaust gas flow between the diesel engine and the U-SCR;a four-way catalyst in fluid communication with the U-SCR catalyst to receive the exhaust gas flow therefrom, the four-way catalyst comprising a monolithic substrate having a plurality of porous cell walls that incorporates a lean nitrogen oxide (NOX)Atrap disposed on the porous cell walls and a diesel particulate filter; anda controller that is configured to control operation of the exhaust gas aftertreatment system and periodic and selective injection of the hydrocarbon, CO or H2 material, or combination thereof, using the hydrocarbon injection device, and periodic and selective injection of the urea or ammonia, or combination thereof using the second injection device, and determine an amount of NOx in the exhaust gas flow, the controller configured to operate in a first mode to minimize consumption of the urea or ammonia, or a combination thereof, and minimize NOX conversion in the U-SCR catalyst or in a second mode to minimize consumption of the hydrocarbon, CO or H2 material, or combination thereof, and minimize NOX conversion in the four-way catalyst. 2. The exhaust gas treatment system of claim 1, wherein the four-way catalyst comprises a plurality of ceramic wall-flow monoliths. 3. The exhaust gas treatment system of claim 1, wherein the exhaust gas treatment system is configured to provide that the exhaust gas flow from the engine has a first volume fraction of NOX (NOX1) and the exhaust gas flow exiting the four-way catalyst has a second volume fraction of NOX (NOX2), and wherein NOX2≦0.1 NOX1. 4. The exhaust gas treatment system of claim 1, wherein the four-way catalyst comprises a ceramic wall flow monolith. 5. The exhaust gas treatment system of claim 4, wherein the lean NOX trap comprises a washcoat disposed on the ceramic wall-flow monolith, the washcoat comprising an oxidation catalyst, an adsorbent and a reduction catalyst disposed on a ceramic matrix. 6. The exhaust gas treatment system of claim 5, wherein the oxidation catalyst comprises Pt or Pd; the adsorbent comprises an oxide or other compound of Ba, Ca, Sr, Mg, K, Na, Li, Cs, La or Y; the reduction catalyst comprises Rh and the ceramic matrix comprises alumina. 7. The exhaust gas treatment system of claim 4, further comprising a second lean NOX trap, the second lean NOX trap comprising a washcoat disposed on a ceramic or metal flow-through monolith. 8. The exhaust gas treatment system of claim 7, wherein the flow-through monolith is disposed to receive the exhaust gas flow prior to or after the wall-flow monolith. 9. The exhaust gas treatment system of claim 7, wherein the flow-through monolith and wall-flow monolith are disposed in a single housing. 10. A method of using an exhaust gas treatment system for a diesel engine comprising a diesel oxidation catalyst (DOC) in fluid communication with the diesel engine to receive an exhaust gas flow therefrom; a hydrocarbon (HC) injection device located between the engine and the DOC that is configured to periodically and selectively inject a hydrocarbon, CO or H2 material, or a combination thereof, into the exhaust gas flow; a urea selective catalytic reduction (U-SCR) catalyst in fluid communication with the DOC to receive the exhaust gas flow therefrom; and a four-way catalyst in fluid communication with the U-SCR to receive the exhaust gas flow therefrom, the four-way catalyst comprising a monolithic wall-flow substrate having a plurality of porous cell walls that incorporates a lean nitrogen oxides (NOX) trap disposed on the porous cell walls and a diesel particulate filter (DPF); a second injection device that is configured to periodically and selectively inject urea or ammonia, or a combination thereof, into the exhaust gas flow between the DOC and the U-SCR catalyst; and a controller that is configured to control operation of the engine and periodic and selective injection of the hydrocarbon, CO or H2 material, or combination thereof, and periodic and selective injection of the urea or ammonia, or combination thereof, and determine an amount of NOX in the exhaust gas flow, the method comprising: configuring the controller to operate in a first mode to minimize consumption of the urea or ammonia, or a combination thereof, and minimize NOX conversion in the U-SCR catalyst or in a second mode to minimize consumption of the hydrocarbon, CO or H2 material, or combination thereof, and minimize NOX conversion in the four-way catalyst;operating the engine to produce the exhaust gas flow, andperiodically and selectively injecting at least one of the hydrocarbon, CO or H2 material, or combination thereof, or the urea or ammonia, or combination thereof, into the exhaust gas flow using the controller to operate the exhaust gas treatment system in the first mode or the second mode. 11. The method of claim 10, wherein periodically and selectively injecting comprises injecting the hydrocarbon, CO or H2 material, or combination thereof, into the exhaust gas flow, wherein the exhaust gas flow from the engine has a first volume fraction of NOX NOX1) and the exhaust gas flow exiting the four-way catalyst has a predetermined second volume fraction of NOX (NOX2) and NOX2≦0.1 NOX1 and wherein the four-way catalyst provides a volume fraction reduction of NOX1 expressed as a third volume fraction of NOX1 (NOX3) in the exhaust gas flow exiting the four-way catalyst, where 0.10NOX1≦NOX3≦0.70NOX1. 12. The method of claim 11, wherein the controller is configured to control the exhaust gas flow from the engine, the hydrocarbon injection device or the second injection device, or a combination thereof, to produce the predetermined second volume fraction of NOX2≦0.1NOX1. 13. The method of claim 11, wherein the controller is configured to operate in the first mode to minimize consumption of urea or ammonia, or a combination thereof, and minimize NOX3. 14. The method of claim 11, wherein periodically and selectively injecting comprises injecting the urea or ammonia, or a combination thereof, into the exhaust gas flow, and wherein the U-SCR catalyst provides a volume fraction reduction of NOX1 expressed as a fourth volume fraction of NOX1 (NOX4), where 0.05NOX1≦NOX4≦0.60NOX1. 15. The method of claim 14, wherein the controller is configured to operate in the second mode to minimize consumption of hydrocarbon, CO or H2 material, or combination thereof, and minimize NOX4. 16. An exhaust gas treatment system for a diesel engine, comprising: a diesel oxidation catalyst (DOC) in fluid communication with the diesel engine to receive an exhaust gas flow therefrom, the DOC disposed in a DOC housing;a hydrocarbon injection device located between the engine and the DOC that is configured to inject a hydrocarbon, CO or H2 material, or a combination thereof, into the exhaust gas flow;a urea selective catalytic reduction (U-SCR) catalyst in fluid communication with the DOC to receive the exhaust gas flow therefrom, the U-SCR catalyst disposed in a U-SCR catalyst housing;a second injection device that is configured to inject urea or ammonia, or a combination thereof, into the exhaust gas flow between the diesel engine and the U-SCR;a four-way catalyst in fluid communication with the U-SCR catalyst to receive the exhaust gas flow therefrom, the four-way catalyst comprising a monolithic wall-flow substrate having a plurality of porous cell walls that incorporates a lean nitrogen oxide trap disposed on the porous cell walls and a diesel particulate filter; anda controller that is configured to control operation of the exhaust gas aftertreatment system and periodic and selective injection of the hydrocarbon, CO or H2 material, or combination thereof using the hydrocarbon injection device, and periodic and selective injection of the urea or ammonia, or combination thereof using the second injection device, and determine an amount of NOX in the exhaust gas flow, the controller configured to operate in a first mode to minimize consumption of the urea or ammonia, or a combination thereof, and minimize NOX conversion in the U-SCR catalyst or in a second mode to minimize consumption of the hydrocarbon, CO or H2 material, or combination thereof, and minimize NOX conversion in the four-way catalyst.
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이 특허에 인용된 특허 (4)
Bly Kenneth B. (Pontiac MI) Stark Terrance L. (Washington MI) Ludecke Otto A. (Rochester MI), Ceramic monolith particulate trap including filter support.
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