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US4488937A
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Separation of m-xylene from o-xylene by extractive distillation
Assignee: Individual
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Filing: 1984-04-11
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Granted: 1984-12-18
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Expires: 2004-04-11
Abstract
Abstract m-Xylene is difficult to separate from o-xylene by conventional rectification or distillation because of the close proximity of their boiling points. m-Xylene can be readily separated from o-xylene by using extractive distillation in which the extractive agent is ethyl-2-hydroxybenzoate; propoxypropanol puls 1,4-butanediol; sulfolane plus dimethylsulfoxide plus ethyl benzoate.
Inventors
- 👤 Lloyd Berg
- 👤 An-I Yeh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 15:14
CPC Classifications
C; C07; C07C; C07C7/00; C07C7/04; C07C7/05; C07C7/08
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
60 words
A method for recovering m-xylene from a mixture of m-xylene and o-xylene which comprises distilling a mixture of m-xylene and o-xylene in a rectification column in the presence of an effective amount of an extractive agent, recovering essentially pure m-xylene as overhead product and obtaining the extractive agent and o-xylene from the stillpot or reboiler, the extractive agent includes sulfolane.
Claim 2
Independent Claim
60 words
A method for recovering m-xylene from a mixture of m-xylene and o-xylene which comprises distilling a mixture of m-xylene and o-xylene in a rectification column in the presence of an effective amount of an extractive agent, recovering essentially pure m-xylene as overhead product and obtaining the extractive agent and o-xylene from the stillpot or reboiler, the extractive agent includes sulfolane.
Claim 3
Dependent Claim
57 words
The method of claim 1 in which the extractive agent comprises a mixture of sulfolane and at least on of the group consisting essentially of: adiponitrile, dimethyl-2-hydroxybenzoate, maleic anhydride, phthalic anhydride, dimethylformamide, nitrobenzene, diethylene glycol, dibutyl phthalate, acetophenone, 1,4-butanediol, benzyl alcohol, benzyl, cyanide, methyl benzoate, ethyl benzoate, isophorone, benzoic acid, phenyl acetic acid, ethylene carbonate, propylene carbonate.
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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) | 1987-12-18 | 1988-06-18 | 1988-12-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-12-18 | 1992-06-18 | 1992-12-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-12-18 | 1996-06-18 | 1996-12-18 | $7700.00 | Window Closed / Lapsed |