Patent US3981971A successfully refreshed from Google Patents.
US3981971A
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Process for reducing nitrogen oxides
Assignee: Kurashiki Spinning Co Ltd
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Filing: 1974-09-04
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Granted: 1976-09-21
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Expires: 1994-09-04
Abstract
Abstract The reduction of nitrogen oxides is effected by passing stack offgases containing nitrogen oxides over a heavy metal sulfide catalyst in an atmosphere where ammonia is present.
Inventors
- 👤 Masumi Saito
- 👤 Sumio Tani
- 👤 Tateo Ito
- 👤 Shigeaki Kasaoka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 22:36
CPC Classifications
B; B01; B01J; B01J37/00; B01J37/20; B01D; B01D53/00; B01D53/34; B01D53/74; B01D53/86; B01D53/8621; B01D53/8625; B01D53/92; B01D53/94; B01D53/9404; B01D53/9409; B01D53/9413; B01J27/00; B01J27/02; B01J27/04; B01J27/043; B01D2251/00; B01D2251/20; B01D2251/206; B01D2251/2062; B01D2255/00; B01D2255/20; B01D2255/204; B01D2255/2047; B01D2255/207; B01D2255/2073; B01D2255/20746; B01D2255/20753; B01D2255/20761; B01D2255/209; B01D2255/2092
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
91 words
A process for reducing nitrogen oxide contained in stack offgases to nitrogen and water which comprises reducing the nitrogen oxide by contacting stack offgases containing nitrogen oxide, oxygen, and sulfur dioxide with ammonia in the presence of a catalyst consisting essentially of a heavy metal sulfide selected from the group consisting of copper sulfide, iron sulfide, and mixtures thereof at a temperature in the range of about 250° to 550°C, the ammonia being present in an amount of from about 0.67 to 4 times the stoichiometric amount of the nitrogen oxide.
Claim 2
Dependent Claim
91 words
A process for reducing nitrogen oxide contained in stack offgases to nitrogen and water which comprises reducing the nitrogen oxide by contacting stack offgases containing nitrogen oxide, oxygen, and sulfur dioxide with ammonia in the presence of a catalyst consisting essentially of a heavy metal sulfide selected from the group consisting of copper sulfide, iron sulfide, and mixtures thereof at a temperature in the range of about 250° to 550°C, the ammonia being present in an amount of from about 0.67 to 4 times the stoichiometric amount of the nitrogen oxide.
Claim 3
Dependent Claim
21 words
A process as claimed in claim 1, wherein the said contacting is carried out at a temperature of 250° to 400°C..
Claim 4
Dependent Claim
33 words
A process as claimed in claim 1, wherein the heavy metal sulfide is used in an amount of about 0.05 to 70 percent by weight with respect to the weight of the catalyst.
Claim 5
Dependent Claim
25 words
A process as claimed in claim 1, wherein the amount of ammonia is from about 1 to 3 times the stoichiometric amount of nitrogen oxide.
References Cited (Backward Citations)
GB384532A
Cited
GB476684A
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US2361825A
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US3223652A
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US3565830A
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US3695828A
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US3857921A
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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) | 1979-09-21 | 1980-03-22 | 1980-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-09-21 | 1984-03-22 | 1984-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-09-21 | 1988-03-22 | 1988-09-21 | $7700.00 | Window Closed / Lapsed |