US3886260A
Expired / Lapsed
US
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Process for reducing nitrogen oxides
Assignee: Monsanto Co
•
Filing: 1972-12-14
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Granted: 1975-05-27
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Expires: 1992-12-14
Abstract
Abstract A catalyst for automotive exhaust clean-up contains very small amounts of rhodium. The compositions are particularly effective for reducing nitrogen oxides.
Inventors
- 👤 Mark Leroy Unland
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 17:06
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/92; B01D53/94; B01D53/9445; B01D53/945; B01J; B01J23/00; B01J23/38; B01J23/40; B01J23/46; B01J23/464; B01J23/70; B01J23/89; B01J23/892; Y; Y02; Y02A; Y02A50/00; Y02A50/20; Y02T; Y02T10/00; Y02T10/10; Y02T10/12
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
100 words
THE PROCESS OF REMOVING NITROGEN OXIO FROM AUTOMOTIVE EXHAUST GASES CONTAINING A SMALL AMOUNT THEREOF ALONG WITH CARBON MONOXIDE, HYDROGEN AND HYDROCARBONS, WHICH COMPRISES CONTACTING SUCH GASES WITH A CATALYST CONTINING RHDIUM IN CATALYTICALLY SIGNIFICANT AMOUNT ON A SUPPORT, IN WHICH PROCESS AN AUTOMOBILE ENGINE IS OPERATED RICHER THAN NECESSARY TO OBTAIN PROPER EXHAUST GASES STOICHIOMETRIES FOR HIGH NOX CONVERSION, AND SUPPLEMENTAL AIR IS ADDED TO THE EXHAUST PRIOR TO CONTACTING THE CATALYST TO OBTAIN PROPER OXYGEN CONTENT TO KEEP THE AMMONIA PRODUCTION AT A VERY LOW LEVEL BUT NOT SUFFICIENT TO PROVENT SUBSTANTIALLY COMPLETE REDUCTION OF THE NITROGEN OXIDES.
Claim 2
Dependent Claim
100 words
THE PROCESS OF REMOVING NITROGEN OXIO FROM AUTOMOTIVE EXHAUST GASES CONTAINING A SMALL AMOUNT THEREOF ALONG WITH CARBON MONOXIDE, HYDROGEN AND HYDROCARBONS, WHICH COMPRISES CONTACTING SUCH GASES WITH A CATALYST CONTINING RHDIUM IN CATALYTICALLY SIGNIFICANT AMOUNT ON A SUPPORT, IN WHICH PROCESS AN AUTOMOBILE ENGINE IS OPERATED RICHER THAN NECESSARY TO OBTAIN PROPER EXHAUST GASES STOICHIOMETRIES FOR HIGH NOX CONVERSION, AND SUPPLEMENTAL AIR IS ADDED TO THE EXHAUST PRIOR TO CONTACTING THE CATALYST TO OBTAIN PROPER OXYGEN CONTENT TO KEEP THE AMMONIA PRODUCTION AT A VERY LOW LEVEL BUT NOT SUFFICIENT TO PROVENT SUBSTANTIALLY COMPLETE REDUCTION OF THE NITROGEN OXIDES.
Claim 3
Dependent Claim
25 words
The process of claim 1 in which the amount of added air is in the range of 0.5 to 25 percent of the exhaust rate.
Claim 4
Dependent Claim
22 words
The process of claim 1 in which the amount of added air is at least 3 percent by volume of the exhaust.
Claim 5
Dependent Claim
26 words
The process of claim 1 in which the amount of added air is in the range of 3 to 6 percent by volume of the exhaust.
Claim 6
Dependent Claim
31 words
The process of claim 1 in which the engine is operated in an air-to-fuel range rich by approximately -0.7 to -1.7 A/F units, and with addition of about 4.3 percent air.
Claim 7
Dependent Claim
13 words
The process of claim 1 in which the catalyst contains rhodium and nickel.
Claim 8
Dependent Claim
30 words
The process of claim 1 in which the rhodium is on a transition alumina surface and present in an amount no greater than 0.005 percent by weight of the support.
Claim 9
Dependent Claim
21 words
The process of claim 7 in which the catalyst contains nickel in an amount of 1 to 10 percent by weight.
Claim 10
Dependent Claim
23 words
The process of claim 1 in which the rhodium is present in an amount no greater than 0.003% by weight of the support.
Claim 11
Dependent Claim
53 words
The process of claim 1 in which the carburetion range of the engine and the amount of added air are in combination such that the amount of added air approaches the maximum which can be added without preventing substantially complete reduction of the nitrogen oxides at the lean edge of the operating range.
Claim 12
Dependent Claim
11 words
The process of claim 10 in which the catalyst contains nickel.
Claim 13
Dependent Claim
51 words
The process of claim 1 in which the air-to-fuel ratio range of the engine and the amount of supplemental air are in relationship such that the CO/O2 ratio in the exhaust after addition of the air is in the range of 1.5 to 5 substantially throughout the said air-to-fuel ratio range.
Claim 14
Dependent Claim
17 words
The process of claim 1 in which the catalyst support consists of an aluimina-coated monolithic ceramic structure.
Claim 15
Dependent Claim
59 words
The process of claim 1 in which additional air is added to the gases from the reduction zone and the gases are contacted with an oxidation catalyst under oxidizing conditions at temperatures on the average high enough to oxidize carbon monoxide and hydrocarbons but not sufficiently high to convert ammonia to NO, and on the average not over 425*C.
Claim 16
Dependent Claim
12 words
The process of claim 14 in which rhodium is dispersed on alumina.
Claim 17
Dependent Claim
42 words
The process of claim 14 in in which oxygen is present in amount low enough that at least 50% reduction of nitrogen oxides is achieved but still sufficient that less than 50 percent of the nitrogen oxides reduced is converted to ammonia.
Claim 18
Dependent Claim
103 words
The process of removing nitrogen oxides from automotive exhaust gases containing a small amount thereof along with carbon monoxide, hydrogen, and hydrocarbons which comprises contacting such gases with rhodium in catalytically significant amounts on a support under conditions which are reducing and with the gases having a CO/O2 ratio maintained within the range of 1.5 to 5 by the operating parameters of the engine producing the gas whereby the average amount of oxygen is such that on the average at least 50 percent reduction of nitrogen oxides is achieved and less than 50 percent of the nitrogen oxides reduced is converted to ammonia.
Claim 19
Dependent Claim
103 words
The process of removing nitrogen oxides from automotive exhaust gases containing a small amount thereof along with carbon monoxide, hydrogen, and hydrocarbons which comprises contacting such gases with rhodium in catalytically significant amounts on a support under conditions which are reducing and with the gases having a CO/O2 ratio maintained within the range of 1.5 to 5 by the operating parameters of the engine producing the gas whereby the average amount of oxygen is such that on the average at least 50 percent reduction of nitrogen oxides is achieved and less than 50 percent of the nitrogen oxides reduced is converted to ammonia.
Claim 20
Dependent Claim
36 words
The process of claim 17 in which oxygen is present in amount such that the CO/O2 ratio is in the range of 1.5 to 5 and in which the rhodium is on a transition alumina support.
References Cited (Backward Citations)
US2601221A
Cited
US3118727A
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US3230034A
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US3224831A
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US3397154A
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US3637344A
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US3733181A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-05-26 | 1978-11-25 | 1979-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-26 | 1982-11-25 | 1983-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-26 | 1986-11-25 | 1987-05-27 | $7700.00 | Window Closed / Lapsed |