US4738755A
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Separation of m-xylene from o-xylene by extractive distillation
Assignee: Individual
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Filing: 1987-03-10
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Granted: 1988-04-19
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Expires: 2007-03-10
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; methyl benzoate plus benzophenone; methyl benzoate, butyl benzoate and dimethylsulfoxide.
Inventors
- 👤 Lloyd Berg
- 👤 An-I Yeh
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 01:25
CPC Classifications
C; C07; C07C; C07C7/00; C07C7/04; C07C7/05; C07C7/08
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
68 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 a benzoate containing from eight to twenty carbon atoms.
Claim 2
Independent Claim
68 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 a benzoate containing from eight to twenty carbon atoms.
Claim 3
Dependent Claim
13 words
The method of claim 1 in which the extractive agent comprises butyl benzoate.
Claim 4
Dependent Claim
13 words
The method of claim 1 in which the extractive agent comprises methyl 2-hydroxybenzoate.
Claim 5
Dependent Claim
13 words
The method of claim 1 in which the extractive agent comprises ethyl 2-hydroxybenzoate.
Claim 6
Dependent Claim
14 words
The method of claim 1 in which the extractive agent comprises diethylene glycol dibenzoate.
Claim 7
Dependent Claim
14 words
The method of claim 1 in which the extractive agent comprises dipropylene glycol dibenzoate.
Claim 8
Dependent Claim
33 words
The method of claim 1 in which the extractive agent comprises methyl benzoate and at least one material from the group consisting of butyl benzoate, ethyl benzoate, diisodecyl phthalate, diphenyl isophthalate and dimethylsulfoxide.
Claim 9
Dependent Claim
42 words
The method of claim 1 in which the extractive agent comprises ethyl benzoate and at least one material from the group consisting of diphenyl terephthalate, ethylene glycol phenyl ether, dimethyl phthalate, dimethylsulfoxide, butyl benzoate, methyl salicylate, benzyl alcohol and benzyl butyl phthalate.
Claim 10
Dependent Claim
40 words
The method of claim 1 in which the extractive agent comprises benzyl benzoate and at least one material from the group consisting of methyl benzoate, butyl benzoate, benzyl butyl phthalate, ethyl-4-hydroxybenzoate, methyl-4-hydroxybenzoate, ethyl-2-hydroxybenzoate, methyl-2-hydroxybenzoate, benzoic acid, ethyl benzoate and dimethylsulfoxide.
Claim 11
Dependent Claim
19 words
The method of claim 1 in which the extractive agent comprises a mixture of butyl benzoate and diphenyl isophthalate.
Claim 12
Dependent Claim
33 words
The method of claim 1 in which the extractive agent comprises methyl 2-hydroxybenzoate and at least one material from the group consisting of diisononyl phthalate, butyl benzoate, methyl benzoate, ethyl benzoate and dimethylsulfoxide.
Claim 13
Dependent Claim
19 words
The method of claim 1 in which the extractive agent comprises a mixture of ethyl 4-hydroxybenzoate and bis-phenol A.
Claim 14
Dependent Claim
33 words
The method of claim 1 in which the extractive agent comprises ethyl-2-hydroxybenzoate and at least one material from the group consisting of methyl benzoate, butyl benzoate, ethyl benzoate, methyl-2-hydroxybenzoate, diphenyl isophthalate and dimethylsulfoxide.
Claim 15
Dependent Claim
35 words
The method of claim 1 in which the extractive agent comprises diethylene glycol dibenzoate and at least one material from the group consisting of methyl benzoate, ethyl benzoate, benzyl benzoate, butyl benzoate, methyl-2-hydroxybenzoate and ethyl-2-hydroxybenzoate.
Claim 16
Dependent Claim
49 words
The method of claim 1 in which the extractive agent comprises dipropylene glycol dibenzoate and at least one material from the group consisting of diphenyl isophthalate, ethyl benzoate, benzyl benzoate, methyl benzoate, ethyl 2-hydroxybenzoate, diethylene glycol dibenzoate, methyl 2-hydroxybenzoate, butyl benzoate, butyl benzyl phthalate, ethyl 4-hydroxybenzoate, adiponitrile and dimethylsulfoxide.
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) | 1991-04-19 | 1991-10-19 | 1992-04-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-04-19 | 1995-10-19 | 1996-04-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-04-19 | 1999-10-19 | 2000-04-19 | $7700.00 | Window Closed / Lapsed |