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US4055623A
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Method of removing nitrogen oxides from a gas as a salt of imidodisulfonic acid
Assignee: Kureha Corp
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Filing: 1976-07-07
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Granted: 1977-10-25
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Expires: 1996-07-07
Abstract
Abstract A method of removing nitrogen oxides from a gas containing nitrogen oxides and converting same to a salt of imidodisulfonic acid, wherein the gas containing nitrogen oxides is brought into contact with an aqueous solution which contains at least one ferrous salt and at least one sulfurous acid alkali salt to absorb the nitrogen oxides in solution in the form of imidodisulfonic acid alkali salts.
Inventors
- 👤 Shigeru Saitoh
- 👤 Tetsuya Watanabe
- 👤 Koji Konno
- 👤 Tadashi Nakamura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:30
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/54; B01D53/56; C; C01; C01C; C01C1/00; C01C1/24; C01C1/245
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
100 words
A method for removing nitrogen oxides from a gas mixture, in the form of a solid salt of imidodisulfonic acid comprising: contacting the gas mixture with an aqueous scrubbing solution containing at least 0.02% by weight of at least one ferrous salt and at least 0.2% by weight of at least an alkali salt of sulfurous acid to absorb the nitrogen oxides, thereby forming an alkali salt of imidodisulfonic acid in solution; cooling the solution containing the alkali salt of imidodisulfonic acid to solidify said alkali salt of imidodisulfonic acid; and separating the solidified salt of imidodisulfonic acid from solution.
Claim 2
Independent Claim
100 words
A method for removing nitrogen oxides from a gas mixture, in the form of a solid salt of imidodisulfonic acid comprising: contacting the gas mixture with an aqueous scrubbing solution containing at least 0.02% by weight of at least one ferrous salt and at least 0.2% by weight of at least an alkali salt of sulfurous acid to absorb the nitrogen oxides, thereby forming an alkali salt of imidodisulfonic acid in solution; cooling the solution containing the alkali salt of imidodisulfonic acid to solidify said alkali salt of imidodisulfonic acid; and separating the solidified salt of imidodisulfonic acid from solution.
Claim 3
Dependent Claim
14 words
The method of claim 1, wherein said alkali is sodium, potassium, calcium or magnesium.
Claim 4
Dependent Claim
10 words
The method of claim 1, wherein said alkali is potassium.
Claim 5
Independent Claim
142 words
A method for removing nitrogen oxides from a gas mixture, in the form of a solid salt of imidodisulfonic acid comprising: contacting the gas mixture with an aqueous scrubbing solution containing at least 0.02% by weight of at least one ferrous salt and at least 0.2% by weight of at least an alkali salt of sulfurous acid to absorb the nitrogen oxide, thereby forming a first alkali salt of imidodisulfonic acid dissolved in the scrubbing solution; adding to the solution a compound selected from the group consisting of ammonium hydroxide, ammonium salts, alkali metal hydroxides, alkali metal salts, alkali earth metalhydroxides and alkali earth metal salts, said compound reacting with said alkali salt of imidodisulfonic acid to form a second salt of imidodisulfonic acid said second salt being a little soluble in said solution; and separating said insoluble second salt from solution.
Claim 6
Independent Claim
142 words
A method for removing nitrogen oxides from a gas mixture, in the form of a solid salt of imidodisulfonic acid comprising: contacting the gas mixture with an aqueous scrubbing solution containing at least 0.02% by weight of at least one ferrous salt and at least 0.2% by weight of at least an alkali salt of sulfurous acid to absorb the nitrogen oxide, thereby forming a first alkali salt of imidodisulfonic acid dissolved in the scrubbing solution; adding to the solution a compound selected from the group consisting of ammonium hydroxide, ammonium salts, alkali metal hydroxides, alkali metal salts, alkali earth metalhydroxides and alkali earth metal salts, said compound reacting with said alkali salt of imidodisulfonic acid to form a second salt of imidodisulfonic acid said second salt being a little soluble in said solution; and separating said insoluble second salt from solution.
Claim 7
Dependent Claim
19 words
The method of claim 4 wherein said compound is a salt or hydroxide of sodium, potassium, calcium or magnesium.
Claim 8
Dependent Claim
13 words
The method of claim 4 wherein said compound is a salt of potassium.
Claim 9
Dependent Claim
11 words
The method of claim 4 wherein said compound is potassium sulfate.
Claim 10
Dependent Claim
16 words
The method of claim 4 wherein said compound is calcium hydroxide, sodium hydroxide or potassium hydroxide.
Claim 11
Dependent Claim
16 words
The method of claim 4 wherein said compound is a calcium salt of an organic acid.
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) | 1980-10-24 | 1981-04-25 | 1981-10-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-24 | 1985-04-25 | 1985-10-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-24 | 1989-04-25 | 1989-10-25 | $7700.00 | Window Closed / Lapsed |