US3887683A
Expired / Lapsed
US
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Method for removing nitrogen oxides from waste gases
Assignee: Shin-Etsu Handotai Co Ltd
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Filing: 1973-08-23
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Granted: 1975-06-03
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Expires: 1993-08-23
Abstract
Abstract Nitrogen oxides contained in waste gases are removed by adding ammonia to the waste gases and passing the resulting mixture through a tower having a contact mass consisting of activated charcoal or vanadium oxides supported on activated charcoal at a space velocity of 1,000 to 50,000 parts by volume of gaseous mixture per hour per part by volume of catalyst at a temperature between room temperature and 150*C. High removal efficiency of nitrogen oxides (higher than 98 percent can be achieved.
Inventors
- 👤 Yasuhiko Abe
- 👤 Hisayoshi Yamaguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 05:38
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/92; B01D53/94; B01D53/9404; B01D53/9409; B01D53/9413; B01D53/9418; B01D2251/00; B01D2251/20; B01D2251/206; B01D2251/2062; B01D2255/00; B01D2255/20; B01D2255/207; B01D2255/20723; B01D2255/70; B01D2255/702; B01D2255/90; B01D2255/92; B01D2255/9202; B01D2255/9207
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
106 words
A METHOD FOR REMOVING NITROGEN OXIDE FROM WASTE GASES WHICH COMPRISES: A. WASHING THE WASTE GAS WITH WATER OR ALKALINE SOLUTION; B. ADDING AMMONIA TO THE WASHED WASTE GAS; C. PASSING THE AMMONIA-WASHED WASTE GAS MIXTURE IN CONTACT WITH A CATALYST SELECTED FROM THE GROUP CONSISTING OF ACTIVATED CHARCOAL AND VANADIUM TRIOXIDE SUPPORTED ON ACTIVATED CHARCOAL AT A TEMPERATURE BETWEEN ROOM TEMPERATURE AND 150*C WITH A SPACE VELOCITY OF FROM 1,000 TO 50,000 PARTS BY VOLUME AT STANDARD TEMPERATURE AND PRESSURE OF THE GAS MIXTURE PER HOUR PER PART BY VOLUME OF THE CATALYST; AND D. SUBJECTING THE THUS-TREATED GASEOUS MIXTURE TO A DUST COLLECTION TREATMENT.
Claim 2
Independent Claim
106 words
A METHOD FOR REMOVING NITROGEN OXIDE FROM WASTE GASES WHICH COMPRISES: A. WASHING THE WASTE GAS WITH WATER OR ALKALINE SOLUTION; B. ADDING AMMONIA TO THE WASHED WASTE GAS; C. PASSING THE AMMONIA-WASHED WASTE GAS MIXTURE IN CONTACT WITH A CATALYST SELECTED FROM THE GROUP CONSISTING OF ACTIVATED CHARCOAL AND VANADIUM TRIOXIDE SUPPORTED ON ACTIVATED CHARCOAL AT A TEMPERATURE BETWEEN ROOM TEMPERATURE AND 150*C WITH A SPACE VELOCITY OF FROM 1,000 TO 50,000 PARTS BY VOLUME AT STANDARD TEMPERATURE AND PRESSURE OF THE GAS MIXTURE PER HOUR PER PART BY VOLUME OF THE CATALYST; AND D. SUBJECTING THE THUS-TREATED GASEOUS MIXTURE TO A DUST COLLECTION TREATMENT.
Claim 3
Independent Claim
106 words
A method for removing nitrogen oxide from waste gases which comprises: a. washing the waste gas with water or alkaline solution; b. adding ammonia to the washed waste gas; c. passing the ammonia-washed waste gas mixture in contact with a catalyst selected from the group consisting of activated charcoal and vanadium trioxide supported on activated charcoal at a temperature between room temperature and 150*C with a spaCe velocity of from 1,000 to 50,000 parts by volume at standard temperature and pressure of the gas mixture per hour per part by volume of the catalyst; and d. subjecting the thus-treated gaseous mixture to a dust collection treatment.
Claim 4
Independent Claim
106 words
A method for removing nitrogen oxide from waste gases which comprises: a. washing the waste gas with water or alkaline solution; b. adding ammonia to the washed waste gas; c. passing the ammonia-washed waste gas mixture in contact with a catalyst selected from the group consisting of activated charcoal and vanadium trioxide supported on activated charcoal at a temperature between room temperature and 150*C with a spaCe velocity of from 1,000 to 50,000 parts by volume at standard temperature and pressure of the gas mixture per hour per part by volume of the catalyst; and d. subjecting the thus-treated gaseous mixture to a dust collection treatment.
Claim 5
Dependent Claim
32 words
The method according to claim 1 in which said vanadium trioxide is produced by decomposing and reducing ammonium metavanadate at a temperature of from 250* to 650*C in a stream of hydrogen.
Claim 6
Dependent Claim
43 words
The method according to claim 1 in which said activated charcoal has a specific surface area of from 800 to 1,500 m2/g, an average diameter of pores of from 10 to 30 A and a bulk density of from 0.3 to 0.9 g/ml.
Claim 7
Dependent Claim
29 words
The method according to claim 1 in which the amount of said ammonia added to said waste gas is 20 percent in excess of the stoichiometrically nitrogen oxide equivalent.
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) | 1978-06-02 | 1978-12-02 | 1979-06-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-02 | 1982-12-02 | 1983-06-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-02 | 1986-12-02 | 1987-06-03 | $7700.00 | Window Closed / Lapsed |