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US4676875A
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Separation of m-xylene from o-xylene by extractive distillation
Assignee: Individual
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Filing: 1986-01-06
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Granted: 1987-06-30
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Expires: 2006-01-06
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 dimethylformamide; dimethylformamide and 1,4-butanediol; dimethylformamide, adiponitrile and dihexyl phthalate.
Inventors
- 👤 Lloyd Berg
- 👤 An-I Yeh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 15:56
CPC Classifications
C; C07; C07C; C07C7/00; C07C7/04; C07C7/05; C07C7/08
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
90 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 about one part of extractive agent per part of m-xylene o-xylene mixture, recovering m-xylene as overhead product and obtaining the extractive agent and o-xylene from the stillpot, the extractive agent comprises dimethylformamide and at least one material from the group consisting of ethylene glycol, 1,4-butanediol, 1,5-pentanediol, diethylene glycol, triethylene glycol, ethylene glycol phenyl ether, adiponitrile, dihexyl phthalate, hydroquinone, m-cresol and p-cresol.
Claim 2
Independent Claim
90 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 about one part of extractive agent per part of m-xylene o-xylene mixture, recovering m-xylene as overhead product and obtaining the extractive agent and o-xylene from the stillpot, the extractive agent comprises dimethylformamide and at least one material from the group consisting of ethylene glycol, 1,4-butanediol, 1,5-pentanediol, diethylene glycol, triethylene glycol, ethylene glycol phenyl ether, adiponitrile, dihexyl phthalate, hydroquinone, m-cresol and p-cresol.
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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) | 1990-06-29 | 1990-12-29 | 1991-06-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-06-29 | 1994-12-29 | 1995-06-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-06-29 | 1998-12-29 | 1999-06-30 | $7700.00 | Window Closed / Lapsed |