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US4039428A
Expired / Lapsed
US
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Purification of propionic acid
Assignee: BP Chemicals Ltd
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Filing: 1976-01-02
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Granted: 1977-08-02
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Expires: 1996-01-02
Abstract
Abstract A process is provided for producing ultra-pure propionic acid, i.e., acid containing less than 20 parts by weight of iodine per billion parts by weight of acid, wherein crude acid containing water and iodine contaminants is distilled in a single distillation zone and no waste streams requiring treatment or disposal are obtained.
Inventors
- 👤 YuWen Wei
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 19:24
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/42; C07C51/47; C07C51/43; C07C51/44; C07C51/487; Y; Y10; Y10S; Y10S203/00; Y10S203/20
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
72 words
A method for purifying a crude propionic acid stream containing water and iodine either as I - , free iodine, ethyl iodide or all of these as contaminants which comprises: 1. introducing said stream into the upper section of a distillation zone, 2. introducing an alkaline compound selected from the group consisting of alkaline compounds of the alkali metals and the alkaline earth metals into the lower third of said distillation zone;
Claim 2
Independent Claim
72 words
A method for purifying a crude propionic acid stream containing water and iodine either as I - , free iodine, ethyl iodide or all of these as contaminants which comprises: 1. introducing said stream into the upper section of a distillation zone, 2. introducing an alkaline compound selected from the group consisting of alkaline compounds of the alkali metals and the alkaline earth metals into the lower third of said distillation zone;
Claim 3
Dependent Claim
121 words
removing overhead from said distillation zone a stream containing the major portion of the water present along with substantially all of the ethyl iodide; 4. removing as a liquid sidestream from the upper section of said distillation zone all of the hydrogen iodide together with the remaining portion of water; 5. withdrawing as a vapor near the bottom of said distillation zone the product propionic acid stream containing less than 20 ppb of iodine; 6. removing a bottoms stream from said distillation zone containing propionic acid, said alkaline compound and metal corrosion products; and 7. passing said bottoms stream through a cation exchange resin and recovering the effluent from said exchange free of said alkaline compound and said metal corrosion products.
Claim 4
Dependent Claim
121 words
removing overhead from said distillation zone a stream containing the major portion of the water present along with substantially all of the ethyl iodide; 4. removing as a liquid sidestream from the upper section of said distillation zone all of the hydrogen iodide together with the remaining portion of water; 5. withdrawing as a vapor near the bottom of said distillation zone the product propionic acid stream containing less than 20 ppb of iodine; 6. removing a bottoms stream from said distillation zone containing propionic acid, said alkaline compound and metal corrosion products; and 7. passing said bottoms stream through a cation exchange resin and recovering the effluent from said exchange free of said alkaline compound and said metal corrosion products.
Claim 5
Dependent Claim
22 words
The process of claim 1 wherein said distillation zone comprises a distillation column having from about 20 to about 80 theoretical trays.
Claim 6
Dependent Claim
20 words
The process of claim 2 wherein said crude propionic acid is introduced into the upper one-third of said distillation column.
Claim 7
Dependent Claim
18 words
The process of claim 3 wherein said alkaline compound is introduced into the lower third of said column.
Claim 8
Dependent Claim
14 words
The process of claim 4 wherein said alkaline compound is a compound of potassium.
Claim 9
Dependent Claim
12 words
The process of claim 5 wherein said potassium compound is potassium hydroxide.
Claim 10
Dependent Claim
28 words
The process of claim 6 wherein the overhead fraction from said column constitutes from about 30 to about 70% by weight of the total feed to said column.
Claim 11
Dependent Claim
28 words
The process of claim 7 wherein said liquid sidedraw from said column constitutes from about 4 to about 10% by weight of the total feed to said column.
Claim 12
Dependent Claim
29 words
The process of claim 8 wherein said bottoms stream from said distillation column constitutes from about 1% to about 5% by weight of the total feed to said column.
Claim 13
Dependent Claim
16 words
The process of claim 9 wherein said cation exchange resin is a strong-acid cation exchange resin.
References Cited (Backward Citations)
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Cited
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US3530043A
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Cited
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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) | 1980-08-01 | 1981-01-31 | 1981-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-08-01 | 1985-01-31 | 1985-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-08-01 | 1989-01-31 | 1989-08-02 | $7700.00 | Window Closed / Lapsed |