US3867508A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Exhaust gas conversion process and apparatus
Assignee: Union Oil Company of California
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Filing: 1973-04-16
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Granted: 1975-02-18
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Expires: 1993-04-16
Abstract
Abstract A process is disclosed for the catalytic conversion of nitrogen oxides, unburned hydrocarbons and carbon monoxide in exhaust gases, utilizing a two-zone conversion system with auxiliary air being injected between the two zones. The basic novel feature of the process involves alternately reversing the direction of gas flow through the two zones so that each zone functions alternately under reducing conditions for the conversion of nitrogen oxides, and under oxidizing conditions for the conversion of carbon monoxide and hydrocarbons.
Inventors
- 👤 Robert H Hass
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 18:38
CPC Classifications
F; F01; F01N; F01N3/00; F01N3/08; F01N3/10; F01N3/18; F01N3/20; F01N3/2093; B; B01; B01D; B01D53/00; B01D53/34; B01D53/92; B01D53/94; B01D53/9404; B01D53/9409; B01D53/9413; B01D53/944; B01D53/9459; B01D53/9463; B01D53/9472; B01J; B01J23/00; B01J23/70; B01J23/76; B01J23/84; B01J23/85; B01J23/86; B01J23/868; F01N13/00; F01N13/009; F01N13/0097; F01N3/02; F01N3/021; F01N3/023; F01N3/0233; F01N3/24; F01N3/28; F01N3/2803; F01N3/2807; F01N3/281; F01N3/30; B01D2251/00; B01D2251/10; B01D2251/102; B01D2251/20; B01D2251/204; B01D2255/00; B01D2255/20; B01D2255/207; B01D2255/20761; B01J35/00; B01J35/50; B01J35/56; Y; Y02; Y02A; Y02A50/00; Y02A50/20
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
96 words
IN A TWO-STAGE CATALYTIC EXHAUST GAS CONVERSION SYSTEM WHEREIN A SUBSTANTIALLY LEAD-FREE EXHAUST GAS CONTAINING CARBON MONOXIDE AND NITROGEN OXIDE IS FIRST PASSED UNDER NOXREDUCING CONDITIONS THROUGH A CONTAINING ZONE CONTAINING A MULTIVALENT TRANSITIONAL METAL OXIDE CONVERSION CATALYST, AND THEN WITH ADDED AIR THROUGH A SECOND CONTACTING ZONE CONTAINING A MULTIVALENT TRANSITIONAL METAL OXIDE CONVERSION CATALYST TO EFFECT OXIDATION OF CARBON MONOXIDE, THE IMPROVED METHOD FOR MAINTAINING CONTINUOUS CONVERSION OF NITROGEN OXIDES WHICH COMPRISES PERIODICALLY REVERSING THE DIRECTION OF FLOW AND THE SEQUENCE IN WHICH THE EXHAUST GAS CONTACTS THE RESPECTIVE CATALYSTS IN SAID CONVERSION ZONES.
Claim 2
Dependent Claim
96 words
IN A TWO-STAGE CATALYTIC EXHAUST GAS CONVERSION SYSTEM WHEREIN A SUBSTANTIALLY LEAD-FREE EXHAUST GAS CONTAINING CARBON MONOXIDE AND NITROGEN OXIDE IS FIRST PASSED UNDER NOXREDUCING CONDITIONS THROUGH A CONTAINING ZONE CONTAINING A MULTIVALENT TRANSITIONAL METAL OXIDE CONVERSION CATALYST, AND THEN WITH ADDED AIR THROUGH A SECOND CONTACTING ZONE CONTAINING A MULTIVALENT TRANSITIONAL METAL OXIDE CONVERSION CATALYST TO EFFECT OXIDATION OF CARBON MONOXIDE, THE IMPROVED METHOD FOR MAINTAINING CONTINUOUS CONVERSION OF NITROGEN OXIDES WHICH COMPRISES PERIODICALLY REVERSING THE DIRECTION OF FLOW AND THE SEQUENCE IN WHICH THE EXHAUST GAS CONTACTS THE RESPECTIVE CATALYSTS IN SAID CONVERSION ZONES.
Claim 3
Dependent Claim
36 words
A method as defined in claim 1 wherein, in each contacting sequence, sufficient air is mixed with the exhaust gas between said contacting zones to provide a stoichiometric excess of O2/CO in the downstream contacting zone.
Claim 4
Dependent Claim
30 words
A method as defined in claim 1 wherein said periodic reversal in contacting sequence is actuated in response to each stopping or starting of the engine supplying said exhaust gas.
Claim 5
Dependent Claim
20 words
A method as defined in claim 1 wherein said contacting zones are maintained in heat exchange relationship to each other.
Claim 6
Dependent Claim
39 words
A method as defined in claim 1 wherein the catalysts in each of said contacting zones are selected from the class consisting of oxides of the metals of Groups IB, VB, VIB, VIIB and VIII of the Periodic Table.
Claim 7
Dependent Claim
21 words
A method as defined in claim 1 wherein the catalysts in each of said contacting zones comprise an oxide of copper.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-17 | 1978-08-19 | 1979-02-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-17 | 1982-08-19 | 1983-02-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-17 | 1986-08-19 | 1987-02-18 | $7700.00 | Window Closed / Lapsed |