Method of manufacturing epsilon-caprolactam

A kind of caprolactam, crude technology, applied in the field of preparing ε-caprolactam, can solve problems such as high purity

Inactive Publication Date: 2012-11-14
SUMITOMO CHEM CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] However, the ε-caprolactam obtained by this method contains various impurities
It is well known that although ε-caprolactam is used as a raw material for polyamides, ε-caprolactam used to prepare polyamides to be used in synthetic fibers or films requires high purity

Method used

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  • Method of manufacturing epsilon-caprolactam
  • Method of manufacturing epsilon-caprolactam

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[0032] The preparation method of ε-caprolactam according to the present invention comprises ε-caprolactam purification step A, first stage ε-caprolactam recovery step B and second stage ε-caprolactam recovery step C. Each step will be described in detail below.

[0033] (ε-caprolactam purification step A)

[0034]Crude ε-caprolactam was obtained by Beckmann gas-phase rearrangement of cyclohexanone oxime using a solid catalyst. Zeolite-based catalysts are suitably employed as solid catalysts. Crude ε-caprolactam in a heated molten state is poured into a crystallizer for drop crystallization [drop crystallization] together with a cooling solvent. As the solvent, examples thereof are straight-chain aliphatic hydrocarbons, side-chain aliphatic hydrocarbons, alicyclic hydrocarbons and the like having a carbon number of 6 to 12. Solvents that are insufficient solvents for ε-caprolactam such as n-heptane and cyclohexane are preferred. A crystallization temperature of about 40°C t...

Embodiment

[0052] Hereinafter, specific examples of the present invention will be described.

[0053] (ε-caprolactam purification step A)

[0054] Perform the following operations continuously. The flow rate is expressed in terms of weight per unit time. The reaction product was obtained by using a zeolite catalyst with a high silica content and causing a gas-phase Beckmann rearrangement reaction of cyclohexanone oxime under the temperature condition of 380° C. in the coexistence of methanol. Low melting point substances and high melting point substances were removed from the reaction product by distillation, whereby crude ε-caprolactam was obtained. The quality of crude ε-caprolactam obtained was based on GC (Gas Chromatography) measurements as follows: 99.131% ε-caprolactam; 139 ppm cyclohexanone oxime (OXM); 398 ppm 3-N-methyl-4 , 5,6,7-tetrahydrobenzimidazole (MTHI); and 430 ppm of 1,2,3,4,6,7,8,9-octahydrophenazine (OHP).

[0055] This crude ε-caprolactam was melted and its temp...

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Abstract

An epsilon-caprolactam manufacturing method capable of manufacturing in good yield, high-quality epsilon-caprolactam containing less impurity has an epsilon-caprolactam purification step A of obtaining purified epsilon-caprolactam from raw epsilon-caprolactam by applying a drop crystallization method, a first-stage epsilon-caprolactam recovery step B of obtaining first recovered epsilon-caprolactam and a first recovered mother liquor by applying an evaporative crystallization method to a crystallization mother liquor obtained in the epsilon-caprolactam purification step A, and a second-stage epsilon-caprolactam recovery step C of obtaining second recovered purified epsilon-caprolactam by applying a melt crystallization method to the first recovered mother liquor, first recovered epsilon-caprolactam being recovered as a raw material for the epsilon-caprolactam purification step A and second recovered purified epsilon-caprolactam being recovered as a raw material for the epsilon-caprolactam purification step A and / or the first-stage epsilon-caprolactam recovery step B.

Description

[technical field] [0001] The present invention relates to a method for preparing ε-caprolactam, and in particular to a method for preparing high-quality ε-caprolactam in good yield by crystallizing crude ε-caprolactam containing impurities, which contains - Caprolactam is obtained by Beckmann rearrangement of cyclohexanone oxime. [Background technique] [0002] ε-caprolactam is an important compound as an intermediate for producing nylon-6, and various methods for producing ε-caprolactam have been known. For example, ε-caprolactam can be produced in large quantities by Beckmann rearrangement of cyclohexanone oxime in the presence of an acid medium such as oleum. This method has the problem of producing a large amount of by-product ammonium sulfate with low added value. [0003] As a method for solving the problem, a method for producing ε-caprolactam based on a gas-phase Beckmann rearrangement reaction using a solid catalyst is known. As solid catalysts to be used in gas-...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D201/16C07D223/10
CPCC07D223/10C07D201/16C07D201/04C07B2200/13
Inventor 永见英人
Owner SUMITOMO CHEM CO LTD
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