US5433933A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of purifying oxygen-excess exhaust gas
Assignee: Tosoh Corp
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Filing: 1993-12-30
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Granted: 1995-07-18
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Expires: 2013-12-30
Abstract
Abstract A method for purifying an exhaust gas containing an excess amount of oxygen, to remove nitrogen oxides, carbon monoxide and hydrocarbons therefrom, by bringing a catalyst into contact with the exhaust gas, the catalyst comprising a zeolite ion-exchanged with (a) cobalt or (b) both cobalt and at least one metal selected from the group consisting of alkaline earth metals and rare earth metals, the zeolite being selected from the group consisting of ferrierite, ZSM-5, ZSM-11, ZSM-12 and ZSM-20, and having a silica-to-alumina molar ratio of from 15 to 1,000.
Inventors
- 👤 Akinori Eshita
- 👤 Senshi Kasahara
- 👤 Shinichi Matsumoto
- 👤 Kazunobu Ishibashi
- 👤 Koji Yokota
- 👤 Shiroh Kondoh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 21:54
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/92; B01D53/94; B01D53/9445; B01D53/945; B01J; B01J29/00; B01J29/04; B01J29/06; B01J29/064; B01J29/072; Y; Y02; Y02A; Y02A50/00; Y02A50/20; Y02T; Y02T10/00; Y02T10/10; Y02T10/12
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
107 words
A method of purifying an exhaust gas containing nitrogen oxides, carbon monoxide, hydrocarbons, and an excess amount of oxygen, which comprises bringing a catalyst into contact with the exhaust gas to remove nitrogen oxides, carbon monoxide and hydrocarbons from the exhaust gas, wherein the nitrogen oxides are reduced without the use of an additional reducing agent, the catalyst comprising a cobalt ion-exchanged zeolite, said zeolite being selected from the group consisting of ferrierite, ZSM-5, ZSM-11, ZSM-12, and ZSM-20 and having a silica to alumina molar ratio of 15 to 1000, the molar amount of cobalt being 1.09 to 1.6 times higher than the molar amount, of alumina.
Claim 2
Independent Claim
107 words
A method of purifying an exhaust gas containing nitrogen oxides, carbon monoxide, hydrocarbons, and an excess amount of oxygen, which comprises bringing a catalyst into contact with the exhaust gas to remove nitrogen oxides, carbon monoxide and hydrocarbons from the exhaust gas, wherein the nitrogen oxides are reduced without the use of an additional reducing agent, the catalyst comprising a cobalt ion-exchanged zeolite, said zeolite being selected from the group consisting of ferrierite, ZSM-5, ZSM-11, ZSM-12, and ZSM-20 and having a silica to alumina molar ratio of 15 to 1000, the molar amount of cobalt being 1.09 to 1.6 times higher than the molar amount, of alumina.
Claim 3
Dependent Claim
20 words
A method according to claim 1, in which the exhaust gas originates from an internal combustion engine of an automobile.
Claim 4
Dependent Claim
19 words
A method according to claim 2, in which the internal combustion engine is run at a lean air-fuel ratio.
Claim 5
Independent Claim
110 words
A method of purifying an exhaust gas containing nitrogen oxides, carbon monoxide, hydrocarbons, and an excess amount of oxygen, which comprises bringing a catalyst into contact with the exhaust gas to remove nitrogen oxides, carbon monoxide and hydrocarbons from the exhaust gas, whereby the nitrogen oxides are reduced without the use of an additional reducing agent, the catalyst comprising a zeolite ion-exchanged with both cobalt and at least one metal selected from the group consisting of alkaline earth metals and rare earth metals, the zeolite being selected from the group consisting of ferrierite, ZSM-5, ZSM-11, ZSM-12, and ZSM-20 and having a silica to alumina molar ratio of 15 to 1000.
Claim 6
Independent Claim
110 words
A method of purifying an exhaust gas containing nitrogen oxides, carbon monoxide, hydrocarbons, and an excess amount of oxygen, which comprises bringing a catalyst into contact with the exhaust gas to remove nitrogen oxides, carbon monoxide and hydrocarbons from the exhaust gas, whereby the nitrogen oxides are reduced without the use of an additional reducing agent, the catalyst comprising a zeolite ion-exchanged with both cobalt and at least one metal selected from the group consisting of alkaline earth metals and rare earth metals, the zeolite being selected from the group consisting of ferrierite, ZSM-5, ZSM-11, ZSM-12, and ZSM-20 and having a silica to alumina molar ratio of 15 to 1000.
Claim 7
Dependent Claim
20 words
A method according to claim 5, in which the exhaust gas originates from an internal combustion engine of an automobile.
Claim 8
Dependent Claim
19 words
A method according to claim 5, in which the internal combustion engine is run at a lean air-fuel ratio.
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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) | 1998-07-17 | 1999-01-16 | 1999-07-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-07-17 | 2003-01-16 | 2003-07-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-07-17 | 2007-01-16 | 2007-07-18 | $7700.00 | Window Closed / Lapsed |