US4199410A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of crude acrylic acid
Assignee: Sumitomo Chemical Co Ltd
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Filing: 1978-07-31
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Granted: 1980-04-22
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Expires: 1998-07-31
Abstract
Abstract A process for purifying crude acrylic acid characterized in that high-purity purified acrylic acid containing little or no low boiling aldehydes is obtained by rectifying a crude acrylic acid consisting essentially of acrylic acid and containing low boiling substances such as acetaldehyde, acrolein, water and acetic acid and/or high boiling substances such as maleic acid, phenol, benzaldehyde and acrylic acid dimer, thereby removing said low boiling substances and then high boiling ones, and then stripping trace amounts of remaining low boiling aldehydes with an inert gas such as nitrogen or air at a liquid to gas molar ratio of 2 to 20.
Inventors
- 👤 Tetsuya Ohrui
- 👤 Michio Kato
- 👤 Masami Ayano
- 👤 Tsunejiro Kawaguchi
- 👤 Tadashi Abe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 19:09
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/42; C07C51/43; C07C51/44; Y; Y10; Y10S; Y10S203/00; Y10S203/22
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
119 words
A process for purifying crude acrylic acid comprising the steps of (1) rectifying a crude acrylic acid consisting essentially of acrylic acid and low boiling impurities including acrolein (a) to remove initially a major portion of said low boiling impurities and then (b) to remove high boiling impurities either present in said crude acrylic acid or the high boiling impurities formed during the initial rectification, and then (2) removing by stripping trace amounts of acrolein and other low boiling impurities with an inert gas at a liquid to gas molar ratio of about 2 to about 20, thereby forming a high purity acrylic acid containing acrolein and other low boiling impurities in a total quantity less than 100 ppm.
Claim 2
Dependent Claim
119 words
A process for purifying crude acrylic acid comprising the steps of (1) rectifying a crude acrylic acid consisting essentially of acrylic acid and low boiling impurities including acrolein (a) to remove initially a major portion of said low boiling impurities and then (b) to remove high boiling impurities either present in said crude acrylic acid or the high boiling impurities formed during the initial rectification, and then (2) removing by stripping trace amounts of acrolein and other low boiling impurities with an inert gas at a liquid to gas molar ratio of about 2 to about 20, thereby forming a high purity acrylic acid containing acrolein and other low boiling impurities in a total quantity less than 100 ppm.
Claim 3
Dependent Claim
19 words
The process of claim 1 wherein said inert gas is selected from the group consisting of nitrogen and air.
Claim 4
Dependent Claim
17 words
The process of claim 1 wherein said crude acrylic acid is formed by the oxidation of propylene.
Claim 5
Dependent Claim
26 words
The process of claim 1 wherein said high purity acrylic acid contains acrolein and other low boiling impurities in a total quantity less than 10 ppm.
Claim 6
Dependent Claim
26 words
The process of claim 1 wherein said high purity acrylic acid contains acrolein and other low boiling impurities in a total quantity less than 5 ppm.
Claim 7
Dependent Claim
17 words
A process according to claim 1, wherein the operating pressure during rectification is less than 400 mmHg.
Claim 8
Dependent Claim
16 words
The process of claim 6 wherein the operating pressure during rectification is less than 100 mmHg.
Claim 9
Dependent Claim
18 words
A process according to claim 1, wherein the stripping temperature of the low boiling impurities is 15°-80° C.
Claim 10
Dependent Claim
19 words
The process of claim 8 wherein the stripping temperature of the low boiling impurities is 20° to 50° C.
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) | 1983-04-22 | 1983-10-22 | 1984-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-04-22 | 1987-10-22 | 1988-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-04-22 | 1991-10-22 | 1992-04-22 | $7700.00 | Window Closed / Lapsed |