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Method for producing high-quality epsilon-caprolactam

A technology for caprolactam and a manufacturing method, which is applied to the separation/purification of lactam, organic chemical methods, chemical instruments and methods, etc., can solve the problems of large by-products and low added value, and achieve the effect of inhibiting scaling

Active Publication Date: 2014-09-03
SUMITOMO CHEM CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this method has the problem that a large amount of ammonium sulfate with low added value is produced as a by-product.

Method used

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  • Method for producing high-quality epsilon-caprolactam
  • Method for producing high-quality epsilon-caprolactam
  • Method for producing high-quality epsilon-caprolactam

Examples

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Embodiment 1

[0159] (refining process)

[0160] A gas-phase Beckmann rearrangement reaction of cyclohexanone oxime was carried out at 380° C. in the presence of methanol using a high-silica zeolite catalyst to obtain a reaction product. Impurities having a lower boiling point than ε-caprolactam and impurities having a higher boiling point than ε-caprolactam were removed from the reaction product by distillation to obtain crude ε-caprolactam.

[0161] Next, the crude ε-caprolactam is heated to 75°C, and the resulting melt and a mixed solvent of n-heptane:cyclohexane=3:1 (weight ratio) cooled to 5°C are simultaneously and continuously injected into the casing to keep the temperature In a crystallization tank at 56°C. The crystallization temperature was 55° C., and the average residence time was 30 minutes.

[0162] The slurry obtained in the crystallization tank is transported to a centrifugal separation type decanter (solid-liquid separator) kept at 55° C., and after solid-liquid separati...

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Abstract

A method for producing high-quality epsilon-caprolactam, comprising: a purification step of allowing epsilon-caprolactam to be crystallized from a mixed solution that is prepared by mixing crude epsilon-caprolactam produced by the Beckmann rearrangement of cyclohexanoneoxime with an organic solvent and then subjecting the resultant solution to solid / liquid separation to produce high-quality epsilon-caprolactam and a drop crystallization-collected mother liquor; and a collection step of evaporating an evaporative crystallization mother liquor containing the drop crystallization-collected mother liquor to cause the crystallization of epsilon-caprolactam and then subjecting the resultant solution to solid / liquid separation to produce collected epsilon-caprolactam and an evaporative crystallization-collected mother liquor. In the method, prior to the collection step, the following steps are involved: a step of mixing the drop crystallization-collected mother liquor with at least a portion of the evaporative crystallization-collected mother liquor, at least a portion of an evaporative crystallization mother liquor that is removed from a vessel in which evaporative crystallization is to be carried out, or both of at least a portion of the evaporative crystallization-collected mother liquor and at least a portion of the evaporative crystallization mother liquor to prepare a mixed solution; and a step of introducing the mixed solution into the vessel and mixing the mixed solution with the evaporative crystallization mother liquor that is stored in the vessel.

Description

technical field [0001] The present invention relates to a method for producing ε-caprolactam, in particular to a method for efficiently obtaining high-quality ε-caprolactam from crude ε-caprolactam containing impurities obtained through Beckmann rearrangement using cyclohexanone oxime. [0002] This application claims priority based on Japanese Patent Application No. 2011-287373 for which it applied to Japan on December 28, 2011, and uses the content here. Background technique [0003] ε-caprolactam is an important compound as an intermediate in the production of nylon-6, and various production methods are known. For example, the Beckmann rearrangement of cyclohexanone oxime in the presence of an acidic medium such as oleum can produce a large amount of ε-caprolactam. However, this method has a problem in that a large amount of ammonium sulfate with low added value is by-produced. [0004] As a method of improving this, there is known a method of producing ε-caprolactam ba...

Claims

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Application Information

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IPC IPC(8): C07D201/16C07D223/10C07B61/00
CPCC07D201/16C07D223/10
Inventor 永见英人尾崎达也
Owner SUMITOMO CHEM CO LTD
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