Patent US6001318A successfully refreshed from Google Patents.
US6001318A
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Process for lowering nitrogen oxide levels in combustion engine exhaust gas
Assignee: DMC2 Degussa Metals Catalysts Cerdec AG
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Filing: 1997-12-22
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Granted: 1999-12-14
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Expires: 2017-12-22
Abstract
Abstract A process is disclosed for lowering nitrogen oxide levels in combustion engine exhaust gas by a reduction catalyst and by controlling the exhaust gas temperature upstream from the catalyst to a constant value, at which the catalyst exhibits maximum conversion for nitrogen oxides. It is possible to maintain maximum conversion over a wide range of engine outlet temperatures of the exhaust gas.
Inventors
- 👤 Hans Van Den Tillaart
- 👤 Jurgen Leyrer
- 👤 Egbert Lox
- 👤 Thomas Kreuzer
- 👤 Stephan Eckhoff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 09:54
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/92; B01D53/94; B01D53/9404; B01D53/9409; B01D53/9495; F; F01; F01N; F01N3/00; F01N3/08; F01N3/10; F01N3/18; F01N3/20; F01N2610/00; F01N2610/03
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
133 words
A process for lowering levels of nitrogen oxides in the exhaust gas stream of lean burn combustion engines comprising catalytically reducing said nitrogen oxides in the presence of a reduction catalyst which reduces nitrogen oxides to nitrogen, using the hydrocarbons and carbon monoxide also present in the exhaust gas as reducing agents, measuring exhaust gas temperature at a point in said stream upstream from said catalyst, and upstream from said point injecting fresh air into the exhaust gas stream to control the temperature of the exhaust gas upstream from the reduction catalyst to a value at which the conversion rate for the nitrogen oxides into nitrogen as the exhaust gas passes in contact with said reduction catalyst is at its maximum to thereby yield nitrogen, water and carbon dioxide in the exhaust gas.
Claim 2
Dependent Claim
133 words
A process for lowering levels of nitrogen oxides in the exhaust gas stream of lean burn combustion engines comprising catalytically reducing said nitrogen oxides in the presence of a reduction catalyst which reduces nitrogen oxides to nitrogen, using the hydrocarbons and carbon monoxide also present in the exhaust gas as reducing agents, measuring exhaust gas temperature at a point in said stream upstream from said catalyst, and upstream from said point injecting fresh air into the exhaust gas stream to control the temperature of the exhaust gas upstream from the reduction catalyst to a value at which the conversion rate for the nitrogen oxides into nitrogen as the exhaust gas passes in contact with said reduction catalyst is at its maximum to thereby yield nitrogen, water and carbon dioxide in the exhaust gas.
Claim 3
Dependent Claim
25 words
The process according to claim 1 wherein as a preliminary step, determining the maximum conversion rate for nitrogen oxide into nitrogen for said reduction catalyst.
Claim 4
Dependent Claim
21 words
The process according to claim 1, further comprising mixing additional reducing agents in gaseous or vapor form into the fresh air.
Claim 5
Dependent Claim
14 words
The process according to claim 1 wherein the reduction catalyst is a DENOX catalyst.
Claim 6
Dependent Claim
20 words
The process according to claim 1 further comprising: measuring the temperature of the exhaust gas upstream from the reduction catalyst.
Claim 7
Dependent Claim
16 words
The process according to claim 1 wherein the air fuel ratio is approximately 1.2 and above.
Claim 8
Dependent Claim
32 words
The process according to claim 1 wherein the exhaust gas is cooled before entry into the reduction catalyst to a temperature at which said catalyst exhibits its maximum conversion for nitrogen oxides.
Claim 9
Dependent Claim
125 words
A process for improving conversion of nitrogen oxides in an exhaust gas stream of a lean burn combustion engine into harmless components by catalytic reduction on a reduction catalyst which reduces nitrogen oxides to nitrogen comprising passing said exhaust gas in contact with said reduction catalyst capable of reducing nitrogen oxides into nitrogen, measuring the temperature of said exhaust gas upstream from the reduction catalyst, and controlling the temperature of said exhaust gas upstream from said reduction catalyst based on said measuring by injecting air into the exhaust gas stream, to thereby bring the temperature of said exhaust gas to a value at which the conversion rate for the nitrogen oxides into harmless components is at its maximum, as previously determined for said reduction catalyst.
Claim 10
Dependent Claim
125 words
A process for improving conversion of nitrogen oxides in an exhaust gas stream of a lean burn combustion engine into harmless components by catalytic reduction on a reduction catalyst which reduces nitrogen oxides to nitrogen comprising passing said exhaust gas in contact with said reduction catalyst capable of reducing nitrogen oxides into nitrogen, measuring the temperature of said exhaust gas upstream from the reduction catalyst, and controlling the temperature of said exhaust gas upstream from said reduction catalyst based on said measuring by injecting air into the exhaust gas stream, to thereby bring the temperature of said exhaust gas to a value at which the conversion rate for the nitrogen oxides into harmless components is at its maximum, as previously determined for said reduction catalyst.
Claim 11
Dependent Claim
30 words
The process according to claim 8 further comprising using the hydrocarbons and carbon monoxide also present in the exhaust gas as reducing agents to yield nitrogen, water and carbon dioxide.
Claim 12
Dependent Claim
25 words
The process according to claim 8, wherein the exhaust gas temperature is cooled to the temperature at which the conversion rate is at a maximum.
Claim 13
Dependent Claim
14 words
The process according to claim 8 wherein the reduction catalyst is a DENOX catalyst.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-12-13 | 2003-06-14 | 2003-12-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-12-13 | 2007-06-14 | 2007-12-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-12-13 | 2011-06-14 | 2011-12-14 | $7700.00 | Window Closed / Lapsed |