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US5662780A
Expired / Lapsed
US
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Process for purifying acetic acid
Assignee: Resonac Holdings Corp
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Filing: 1996-03-06
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Granted: 1997-09-02
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Expires: 2016-03-06
Abstract
Abstract A process for purifying acetic acid which comprises: introducing a feedstock aqueous solution of acetic acid having an acetic acid concentration of from 10 to 50% by weight into an extractor; supplying an extracting medium containing isopropyl acetate in an amount from 0.6 to 3.0 times by weight the amount of the feedstock solution thereinto in such a manner that the extracting medium is made in contact with the feedstock solution; extracting acetic acid into the extracting medium; separating the extracting medium containing acetic acid from an extraction residue; supplying the extraction medium containing acetic acid into an azeotropic distillation column; distilling off the isopropyl acetate contained in the extraction medium from a top of the azeotropic distillation column via azeotropic distillation with water; condensing a distillate from the top of the azeotropic distillation column, to divide the distillate into a water-poor phase being rich in isopropyl acetate and a water-rich phase being rich in water; returning at least a portion of the water-poor phase into the extractor as the extracting medium; and recovering the acetic acid, which has been thus dehydrated and purified, from a bottom of the azeotropic distillation column.
Inventors
- 👤 Takaharu Sasaki
- 👤 Masayuki Fujimoto
- 👤 Takashige Miyanari
- 👤 Hiroshi Nishino
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 20:33
CPC Classifications
C; C07; C07C; C07C51/00; C07C51/42; C07C51/48; C07C53/00; C07C53/08
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
188 words
A process for purifying acetic acid which comprises: introducing a feedstock aqueous solution of acetic acid having an acetic acid concentration of from 10 to 50% by weight into an extractor; supplying an extracting medium containing isopropyl acetate in an amount from 0.6 to 3.0 times by weight the amount of said feedstock solution thereinto in such a manner that said extracting medium contacts said feedstock solution; extracting acetic acid into said extracting medium; separating said extracting medium containing acetic acid from an extraction residue; supplying said extraction medium containing acetic acid into an azeotropic distillation column; distilling off said isopropyl acetate contained in said extraction medium from a top of said azeotropic distillation column via azeotropic distillation with water; condensing a distillate from said top of said azeotropic distillation column, to divide said distillate into a water-poor phase being rich in isopropyl acetate and a water-rich phase being rich in water; returning at least a portion of said water-poor phase into said extractor as said extracting medium; and recovering said acetic acid, which has been thus dehydrated and purified, from a bottom of said azeotropic distillation column.
Claim 2
Dependent Claim
188 words
A process for purifying acetic acid which comprises: introducing a feedstock aqueous solution of acetic acid having an acetic acid concentration of from 10 to 50% by weight into an extractor; supplying an extracting medium containing isopropyl acetate in an amount from 0.6 to 3.0 times by weight the amount of said feedstock solution thereinto in such a manner that said extracting medium contacts said feedstock solution; extracting acetic acid into said extracting medium; separating said extracting medium containing acetic acid from an extraction residue; supplying said extraction medium containing acetic acid into an azeotropic distillation column; distilling off said isopropyl acetate contained in said extraction medium from a top of said azeotropic distillation column via azeotropic distillation with water; condensing a distillate from said top of said azeotropic distillation column, to divide said distillate into a water-poor phase being rich in isopropyl acetate and a water-rich phase being rich in water; returning at least a portion of said water-poor phase into said extractor as said extracting medium; and recovering said acetic acid, which has been thus dehydrated and purified, from a bottom of said azeotropic distillation column.
Claim 3
Dependent Claim
101 words
A process for purifying acetic acid as claimed in claim 1, wherein said process comprises supplying said extraction residue and at least a portion of said water-rich phase into a recovery/distillation column; azeotropically distilling isopropyl acetate contained in said extraction residue and said water-rich phase with water; condensing a distillate distilled off from a top of said recovery/distillation column to divide into a water-poor phase being rich in isopropyl acetate and a water-rich phase being rich in water; discharging at least a portion of said water-poor phase from a system; and discharging waste water from a bottom of said recovery/distillation column.
Claim 4
Dependent Claim
53 words
A process for purifying acetic acid as claimed in claim 2, wherein said process comprises introducing said water-poor phase, which has been discharged from the system, into an esterification reactor together with acetic acid; and converting isopropyl alcohol, which has been produced by hydrolysis of isopropyl acetate, into isopropyl acetate followed by recovery.
Claim 5
Dependent Claim
40 words
A process for purifying acetic acid as claimed in claim 3, wherein said acetic acid introduced into said esterification reactor together with said water-poor phase is a portion of acetic acid recovered from said bottom of said azeotropic distillation column.
Claim 6
Dependent Claim
43 words
A process for purifying acetic acid as claimed in claim 1, wherein the process comprises supplying said extraction residue into an extracting medium recovery column; and returning a distillate distilled off from a top of said extracting medium recovery column to said extractor.
Claim 7
Dependent Claim
60 words
A process for purifying acetic acid as claimed in claim 5, wherein the process comprises supplying said water-rich phase divided from said condensed distillate from said top of said azeotropic distillation column to a stripper; returning a distillate distilled off from a top of said stripper to said azeotropic distillation column; and withdrawing water from a bottom of said stripper.
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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) | 2000-09-01 | 2001-03-03 | 2001-09-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-09-01 | 2005-03-03 | 2005-09-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-09-01 | 2009-03-03 | 2009-09-02 | $7700.00 | Window Closed / Lapsed |