Patent US4493818A successfully refreshed from Google Patents.
US4493818A
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Phosgene removal process
Assignee: Dow Chemical Co
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Filing: 1984-01-27
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Granted: 1985-01-15
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Expires: 2004-01-27
Abstract
Abstract Phosgene is removed from an off gas containing phosgene by contacting the off gas with an aqueous solution containing alkali metal hydroxide and a tertiary amine compound having 3 to 20 carbon atoms. The concentration of the alkali metal hydroxide can vary from 1 to 25 weight percent and the concentration of the tertiary amine can be any amount which is effective in the contact apparatus chosen. The amines found to be useful are trialkyl amines having 1 to 4 carbon atoms and pyridines having 0 to 3 alkyl groups of 1 to 5 carbon atoms and diamines such as 4-dimethylaminepyridine.
Inventors
- 👤 James R. Gross
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 13:50
CPC Classifications
B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/68; B01D53/70
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
48 words
A process for removing phosgene from an off gas containing phosgene which comprises contacting said off gas with an aqueous solution comprising 1 to 25 weight percent of an alkali metal hydroxide and an amount effective to remove phosgene of a tertiary amine compound having 3-20 carbon atoms.
Claim 2
Dependent Claim
48 words
A process for removing phosgene from an off gas containing phosgene which comprises contacting said off gas with an aqueous solution comprising 1 to 25 weight percent of an alkali metal hydroxide and an amount effective to remove phosgene of a tertiary amine compound having 3-20 carbon atoms.
Claim 3
Dependent Claim
35 words
The process as set forth in claim 1 wherein the amount of said alkali metal hydroxide is 5 to 10 weight percent and the amount of said tertiary amine is 0.02 to 20.0 weight percent.
Claim 4
Dependent Claim
16 words
The process as set forth in claim 1 wherein the alkali metal hydroxide is sodium hydroxide.
Claim 5
Dependent Claim
14 words
The process as set forth in claim 1 wherein the tertiary amine is pyridine.
Claim 6
Dependent Claim
17 words
The process as set forth in claims 1, 2 or 3 wherein the tertiary amine is triethylamine.
Claim 7
Dependent Claim
73 words
A process for removing phosgene from an off gas containing phosgene which comprises contacting said off gas with an aqueous solution comprising 1 to 25 weight percent of an alkali metal hydroxide and 0.2 to 10 weight percent of a tertiary amine selected from the group consisting of trialkylamines having 1 to 4 carbon atoms in the alkyl moiety and pyridines having 0 to 3 alkyl groups of 1 to 5 carbon atoms.
Claim 8
Dependent Claim
73 words
A process for removing phosgene from an off gas containing phosgene which comprises contacting said off gas with an aqueous solution comprising 1 to 25 weight percent of an alkali metal hydroxide and 0.2 to 10 weight percent of a tertiary amine selected from the group consisting of trialkylamines having 1 to 4 carbon atoms in the alkyl moiety and pyridines having 0 to 3 alkyl groups of 1 to 5 carbon atoms.
Claim 9
Dependent Claim
35 words
The process as set forth in claim 6 wherein the amount of said alkali metal hydroxide is 5 to 10 weight percent and the amount of said tertiary amine is 0.02 to 20.0 weight percent.
Claim 10
Dependent Claim
16 words
The process as set forth in claim 6 wherein the alkali metal hydroxide is sodium hydroxide.
Claim 11
Dependent Claim
14 words
The process as set forth in claim 6 wherein the tertiary amine is pyridine.
Claim 12
Dependent Claim
17 words
The process as set forth in claims 6, 7 or 8 wherein the tertiary amine is triethylamine.
References Cited (Backward Citations)
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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) | 1988-01-15 | 1988-07-16 | 1989-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-01-15 | 1992-07-16 | 1993-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-01-15 | 1996-07-16 | 1997-01-15 | $7700.00 | Window Closed / Lapsed |