| 摘要 |
PROBLEM TO BE SOLVED: To obtainε-caprolactam having a high quality by efficiently removing by-products by a highly profitable method comprising crystallizing crudeε- caprolactam in a hydrocarbon-based solvent and then bringing the product into contact with hydrogen in the presence of a hydrogenation catalyst. SOLUTION: This method for purifying (ε-caprolactam comprises crystallizing crude (ε-caprolactam in a hydrocarbon-based solvent and then bringing the product with contact with hydrogen in the presence of a hydrogenation catalyst (for example, an egg shell type carried catalyst prepared by carrying palladium). The hydrocarbon-based solvent used for the crystallization includes 6-12C aliphatic hydrocarbons and aliphatic hydrocarbons, especially preferably cyclohexane, heptane and isooctane, and is used in an amount of about 0.5-5 weight times, especially about l-4 weight times, that of the lactam. The crystallization is carried out, for example, by dissolving the crude lactam in the solvent and then cooling the solution to deposit the crystals. Therein, the temperature is preferably about 10 deg.C to a temperature below the melting point of the lactam, more preferably about 30-60 deg.C.
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