IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0684246
(2007-03-09)
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등록번호 |
US-8240132
(2012-08-14)
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발명자
/ 주소 |
- Gandhi, Haren S.
- Cavataio, John Vito
- Hammerle, Robert Henry
- Cheng, Yisun
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출원인 / 주소 |
- Ford Global Technologies, Inc.
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대리인 / 주소 |
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인용정보 |
피인용 횟수 :
2 인용 특허 :
33 |
초록
▼
This catalyst system simultaneously removes ammonia and enhances net NO, conversion by placing an NH3-SCR catalyst formulation downstream of a lean NOx trap. By doing so, the NH3-SCR catalyst adsorbs the ammonia from the upstream lean NOx trap generated during the rich pulses. The stored ammonia the
This catalyst system simultaneously removes ammonia and enhances net NO, conversion by placing an NH3-SCR catalyst formulation downstream of a lean NOx trap. By doing so, the NH3-SCR catalyst adsorbs the ammonia from the upstream lean NOx trap generated during the rich pulses. The stored ammonia then reacts with the NOx emitted from the upstream lean NOx trap—enhancing the net NOx conversion rate significantly, while depleting the stored ammonia. By combining the lean NOx trap with the NH3-SCR catalyst, the system allows for the reduction or elimination of NH3 and NOx slip, reduction in NOx spikes and thus an improved net NOx conversion during lean and rich operation.
대표청구항
▼
1. A method of controlling NOx and NH3 emissions from an exhaust stream of a diesel engine, comprising: providing a lean NOx trap, having a rich and lean cycle, in communication with the diesel exhaust stream;operating the lean NOx trap at a temperature of 150°-300° C. and elongating the rich cycle,
1. A method of controlling NOx and NH3 emissions from an exhaust stream of a diesel engine, comprising: providing a lean NOx trap, having a rich and lean cycle, in communication with the diesel exhaust stream;operating the lean NOx trap at a temperature of 150°-300° C. and elongating the rich cycle, wherein the lean NOx trap, produces and releases an optimum amount of NH3 to provide a NOx reduced diesel exhaust stream including NOx and an optimum amount of NH3;providing an NH3-SCR catalyst, which does not require injection of a reducing agent, in communication with the NOx reduced diesel exhaust stream, for adsorbing NH3, wherein the NH3 adsorbed by the NH3-SCR catalyst reacts with NOx in the NOx reduced diesel exhaust stream to improve the reduction of NOx and NH3; andwherein when the engine is run rich sufficient reductants and an optimum amount of NH3 are generated in situ over the lean NOx trap, to force the reaction between NOx and NH3, such that NH3 emissions are controlled and net NOx conversion maximized by the NH3-SCR catalyst operating in conjunction with the lean NOx trap. 2. The method of claim 1, wherein the lean NOx trap is optimized for NH3 generation by minimizing oxygen storage capacity. 3. A method of controlling NOx and NH3 emissions from an exhaust stream of a diesel engine, comprising: providing a single lean NOx trap in communication with the diesel exhaust stream for NOx reduction; operating the lean NOx trap at a temperature of 150° C.-300° C. to optimize the in situ production of NH3 and provide a NOx reduced diesel exhaust stream including NOx and an optimum amount of NH3;providing a single NH3-SCR catalyst, which does not require injection of a reducing agent, in communication with the NOx reduced diesel exhaust stream for adsorbing NH3 such that the NH3 adsorbed by the NH3-SCR catalyst reacts with NOx in the NOx reduced diesel exhaust stream to improve the reduction of NOx and NH3 and enhance net NOx conversion to at least 80%, eliminating the need for additional precious-metal catalysts. 4. A method of controlling NOx and NH3 emissions from an exhaust stream of a diesel engine, comprising: providing a lean NOx trap in communication with the exhaust stream for NOx reduction to provide a NOx reduced diesel exhaust stream including NOx and NH3;providing an NH3-SCR catalyst in communication with the NOx reduced diesel exhaust stream, for adsorbing NH3, wherein the NH3 adsorbed by the NH3-SCR catalyst reacts with NOx in the NOx reduced diesel exhaust stream to improve the reduction of NOx and NH3; andwherein an excess quantity of NH3 is generated in situ by minimizing the oxygen storage capacity of the lean NOx trap, and facilitating the reaction between NOx and NH3, to improve net NOx conversion. 5. A method of controlling NOx and NH3 emissions from an exhaust stream of a diesel engine, comprising: providing a lean NOx trap in communication with the exhaust stream, wherein the lean NOx trap produces an optimum amount of NH3 to provide a NOx reduced diesel exhaust stream including NOx and an optimum amount of NH3,providing an NH3-SCR catalyst in downstream of the lean NOx trap, for adsorbing NH3 from the NOx reduced diesel exhaust stream, wherein the NH3 adsorbed by the NH3-SCR catalyst reacts with NOx in the NOx reduced diesel exhaust stream to improve the reduction of NOx and NH3;placing the NH3-SCR catalyst in mating engagement with the lean NOx trap, wherein the mating engagement of the catalysts minimizes the chance for NH3 to be converted back to NOx; andwherein when the engine is run rich sufficient reductants and an optimum amount of NH3 are generated in situ over the lean NOx trap and available for reaction with the NOx stored by the NH3-SCR catalyst, to force the reaction between NOx and NH3, such that NH3 emissions are controlled and net NOx conversion maximized. 6. A method of controlling NOx and NH3 emissions from an exhaust stream of a diesel engine, comprising: providing a lean NOx trap in communication with the diesel exhaust stream, wherein the lean NOx trap comprises platinum and the lean NOx trap produces and releases an optimum amount of NH3 by lowering the lambda ratio to below 1.0 to provide a NOx reduced diesel exhaust stream including NOx and an optimum amount of NH3;providing an NH3-SCR catalyst, which does not require injection of a reducing agent, in communication with the NOx reduced diesel exhaust stream, for adsorbing NH3, wherein the NH3 adsorbed by the NH3 SCR catalyst reacts with NOx in the NOx reduced diesel exhaust stream to improve the reduction of NOx and NH3; andwherein when the engine is run rich sufficient reductants and an optimum amount of NH3 are generated in situ over the lean NOx trap, to force the reaction between NOx and NH3, such that NH3 emissions are controlled and net NOx conversion maximized. 7. The method of claim 5, further comprising the step of placing the lean NOx trap and the NH3-SCR catalyst on a single substrate. 8. The method of claim 5, further comprising the step of placing the lean NOx trap and the NH3-SCR catalyst in one or more alternating zones on a single substrate. 9. A method of controlling NOx and NH3 emissions from an exhaust stream of a diesel engine, comprising: providing a lean NOx trap, having a lean cycle and a rich cycle, in communication with the diesel exhaust stream;elongating the rich cycle of the lean NOx trap, so that the lean NOx trap produces and releases an optimum amount of NH3 in situ during the rich cycle of the lean NOx trap to provide a NOx reduced diesel exhaust stream including NO, NO2 and N20 and an optimum amount of NH3;providing an NH3-SCR catalyst, which does not require injection of a reducing agent, in communication with the NOx reduced diesel exhaust stream to adsorb and store NH3 released from the lean NOx trap;depleting NH3 stored by the NH3-SCR catalyst during the SCR reaction wherein NO, NO2 and N20 released from the lean NOx trap are reacted with the NH3 stored on the NH3-SCR catalyst to produce nitrogen and to maximize net NOx reduction.
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