US3907781A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for recovery of {68 -caprolactam from a reaction mixture of {68 -caprolactam and sulphuric acid
Assignee: Stamicarbon BV
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Filing: 1974-06-24
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Granted: 1975-09-23
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Expires: 1994-06-24
Abstract
Abstract Epsilon -CAPROLACTAM IS RECOVERED FROM A Beckmann rearrangement mixture of the lactam and aqueous sulfuric acid by simultaneously neutralizing the rearrangement mixture with ammonia at a pressure of 1-5 atmospheres and crystallizing out ammonium sulfate, the heat liberated by the neutralization reaction is removed from the system by evaporating a portion of the water from the solution. At the conditions employed hydrolysis of the lactam is substantially reduced if not entirely avoided.
Inventors
- 👤 Rooij Abraham H De
- 👤 Jan Elmendorp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:04
CPC Classifications
C; C07; C07D; C07D201/00; C07D201/16; E; E05; E05Y; E05Y2900/00; E05Y2900/10; E05Y2900/104
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
160 words
A CONTINUOUS PROCESS FOR THE RECOVERY OF -CAPROLACTAM FROM A SYNTHESIS REACTION MIXTURE COMPOSED OF THE LACTAM AND SULFURIC ACID BY CONCURRENTLY NEUTRALIZING AND CRYSTALLIZING THE SYNTHESIS REACTION MIXTURE, COMPRISING THE STEPS OF NEUTRALIZING THE SYNTHESIS REACTION MIXTURE WITH AMMONIA IN A CIRCULATING VOLUME OF AMMONIUM SULFATE SOLUTION AT A PRESSURE OF 1-5 ATMOSPHERES IN A NEUTRALIZATION ZONE, THE NEUTRALIZATION SIMULTANEOUSLY FORMING ADDITIONAL AMMONIUM SULFATE CRYSTALS AND LIBERATING HEAT, PASSING THE CRYSTAL-RICH NEUTRALIZED MIXTURE TO A BOILING AREA AND CAUSING THE MIXTURE TO BOIL AND WATER VAPOR TO BE DISCHARGE FROM THE MIXTURE, SEPARATING THE NEUTRALIZED SOLUTION INTO A SUPERNATENT LAYER LACTAM-RICH AQUEOUS SOLUTION AND A SUSPENSION OF AMMONIUM SULPHATE CRYSTALS IN AMMONIUM SULPHATE SOLUTION, RECOVERING THE LACTAM-RICH LAYER, SEPARATING THE AMMONIUM SULPHATE CRYSTALS FROM THE SUSPENSION, RECYCLING THE SEPARATED MOTHER LIQUOR TO THE NEUTRALIZATION ZONE, WHEREBY THE HEAT GENERATED BY THE NEUTRALIZATION REACTION IS DISCHARGE OUT OF THE SYSTEM BY EVAPORATION PORTION OF THE WATER OF THE RECIRCULATING MIXTURE.
Claim 2
Dependent Claim
160 words
A CONTINUOUS PROCESS FOR THE RECOVERY OF -CAPROLACTAM FROM A SYNTHESIS REACTION MIXTURE COMPOSED OF THE LACTAM AND SULFURIC ACID BY CONCURRENTLY NEUTRALIZING AND CRYSTALLIZING THE SYNTHESIS REACTION MIXTURE, COMPRISING THE STEPS OF NEUTRALIZING THE SYNTHESIS REACTION MIXTURE WITH AMMONIA IN A CIRCULATING VOLUME OF AMMONIUM SULFATE SOLUTION AT A PRESSURE OF 1-5 ATMOSPHERES IN A NEUTRALIZATION ZONE, THE NEUTRALIZATION SIMULTANEOUSLY FORMING ADDITIONAL AMMONIUM SULFATE CRYSTALS AND LIBERATING HEAT, PASSING THE CRYSTAL-RICH NEUTRALIZED MIXTURE TO A BOILING AREA AND CAUSING THE MIXTURE TO BOIL AND WATER VAPOR TO BE DISCHARGE FROM THE MIXTURE, SEPARATING THE NEUTRALIZED SOLUTION INTO A SUPERNATENT LAYER LACTAM-RICH AQUEOUS SOLUTION AND A SUSPENSION OF AMMONIUM SULPHATE CRYSTALS IN AMMONIUM SULPHATE SOLUTION, RECOVERING THE LACTAM-RICH LAYER, SEPARATING THE AMMONIUM SULPHATE CRYSTALS FROM THE SUSPENSION, RECYCLING THE SEPARATED MOTHER LIQUOR TO THE NEUTRALIZATION ZONE, WHEREBY THE HEAT GENERATED BY THE NEUTRALIZATION REACTION IS DISCHARGE OUT OF THE SYSTEM BY EVAPORATION PORTION OF THE WATER OF THE RECIRCULATING MIXTURE.
Claim 3
Dependent Claim
17 words
The process according to claim 1 wherein the neutralization is effected at a pressure of 1-2 atmospheres.
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) | 1978-09-22 | 1979-03-24 | 1979-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-22 | 1983-03-24 | 1983-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-22 | 1987-03-24 | 1987-09-23 | $7700.00 | Window Closed / Lapsed |