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US5441607A
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Recovery of caprolactam from distillation residues obtained in the purification of caprolactam
Assignee: BASF SE
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Filing: 1994-06-27
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Granted: 1995-08-15
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Expires: 2014-06-27
Abstract
Abstract Recovery of caprolactam and of an alkali metal carbonate from distillation residues which are obtained in the purification of caprolactam and contain caprolactam and/or oligomers and/or polymers of caprolactam and also alkali metal hydroxides by (a) melting the distillation residues, the caprolactam and/or oligomers and/or polymers of caprolactam and alkali metal hydroxides, (b) continuously removing caprolactam from the melt, (c) after removing caprolactam, cooling the melt and obtaining a residue, (d) dissolving the residue thus obtained in water and (e) subjecting the aqueous solution thus obtained to combustion with the formation of an alkali metal carbonate is described.
Inventors
- 👤 Hugo Fuchs
- 👤 Josef Ritz
- 👤 Hans J. Wilfinger
- 👤 David Weatherford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 16:07
CPC Classifications
C; C07; C07D; C07D201/00; C07D201/14; C07D201/02; C07D201/12; C07D201/16
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
89 words
A process for recovering caprolactam and an alkali metal carbonate from distillation residues which are obtained in the purification of caprolactam and contain caprolactam and oligomers of caprolactam and also alkali metal hydroxides, which comprises (a) melting the distillation residues, the caprolactam and obligomers of caprolactam and alkali metal hydroxides, (b) continuously removing caprolactam from the melt, (c) cooling the melt to obtain a residue, (d) dissolving the residue in water and (e) subjecting the aqueous solution thus obtained to combustion with the formation of an alkali metal carbonate.
Claim 2
Dependent Claim
89 words
A process for recovering caprolactam and an alkali metal carbonate from distillation residues which are obtained in the purification of caprolactam and contain caprolactam and oligomers of caprolactam and also alkali metal hydroxides, which comprises (a) melting the distillation residues, the caprolactam and obligomers of caprolactam and alkali metal hydroxides, (b) continuously removing caprolactam from the melt, (c) cooling the melt to obtain a residue, (d) dissolving the residue in water and (e) subjecting the aqueous solution thus obtained to combustion with the formation of an alkali metal carbonate.
Claim 3
Dependent Claim
19 words
The process of claim 1, wherein caprolactam is removed from the melt using superheated steam or an inert gas.
Claim 4
Dependent Claim
33 words
The process of claim 1, wherein superheated steam or an inert gas having a temperature in the range of from 250° to 450° C. is used to remove the caprolactam from the melt.
Claim 5
Dependent Claim
20 words
The process of claim 1, wherein the alkali metal hydroxide is sodium hydroxide or potassium hydroxide or a mixture thereof.
Claim 6
Dependent Claim
18 words
The process of claim 1, wherein the caprolactam is removed from the melt by applying a reduced pressure.
Claim 7
Dependent Claim
20 words
The process of claim 1, wherein the distillation residues obtained in the purification of caprolactam also contain polymers of caprolactam.
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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) | 1998-08-14 | 1999-02-13 | 1999-08-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-08-14 | 2003-02-13 | 2003-08-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-08-14 | 2007-02-13 | 2007-08-15 | $7700.00 | Window Closed / Lapsed |