Patent ID: 8193348
Filing Date: 2012-06-05
Classification: C07D

Abstract:
1. A method for recovering caprolactam from a rearrangement mixture of cyclohexanone oxime and sulfuric acid, comprising the steps of: (a) neutralizing the rearrangement mixture with a base in a neutralization device to obtain a first crude lactam solution containing impurities above a standard value and a second crude lactam solution containing impurities below the standard value; (b) feeding the first crude lactam solution into a temporary storage device, and feeding the second crude lactam solution into a buffering device; (c1) feeding a first organic solvent and the first crude lactam solution in the temporary storage device into a temporary extraction device, allowing the first crude lactam solution to be in contact with the first organic solvent to perform batch extraction, so as to obtain a first lactam solution and a first impurity containing a minor amount of organic solvents; (c2) feeding a second organic solvent and one of the second crude lactam solution in the buffering device and a combination of the second crude lactam solution and the first lactam solution continuously into an extraction device to perform continuous extraction, so as to obtain a second lactam solution and a second impurity containing a minor amount of organic solvents; and (d) recovering caprolactam from the second lactam solution after the continuous extraction.