Patent US5094725A successfully refreshed from Google Patents.
US5094725A
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Separation of m-xylene from o-xylene by extractive distillation with esters
Assignee: Individual
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Filing: 1991-04-04
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Granted: 1992-03-10
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Expires: 2011-04-04
Abstract
Abstract m-Xylene is difficult to separate from o-xylene by conventional distillation or rectification 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 agent is an aliphatic ester. Typical examples of effective agents are diethyl maleate, diethyl malonate or 2-ethyl hexyl acetate.
Inventors
- 👤 Lloyd Berg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 15:34
CPC Classifications
C; C07; C07C; C07C7/00; C07C7/04; C07C7/05; C07C7/08
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
73 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 the presence of about one part of an extractive agent per part of m-xylene--o-xylene mixture, recovering the m-xylene as overhead product and obtaining the o-xylene and the extractive agent from the stillpot, wherein said extractive agent consists of one material selected from the group consisting of diethyl maleate and diethyl malonate.
Claim 2
Independent Claim
73 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 the presence of about one part of an extractive agent per part of m-xylene--o-xylene mixture, recovering the m-xylene as overhead product and obtaining the o-xylene and the extractive agent from the stillpot, wherein said extractive agent consists of one material selected from the group consisting of diethyl maleate and diethyl malonate.
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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) | 1995-03-10 | 1995-09-09 | 1996-03-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-03-10 | 1999-09-09 | 2000-03-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-03-10 | 2003-09-09 | 2004-03-10 | $7700.00 | Window Closed / Lapsed |