Process for extracting and washing cyclohexane oxime

Abstract

The invention discloses a process for extracting and washing cyclohexane oxime. The process comprises the following steps of: extracting an extractant and aqueous solution of cyclohexane oxime in a weight part ratio of 1:1 to 2:1 at the temperature of between 45 and 55 DEG C; washing an organic phase obtained by the extraction with desalted water when the mass concentration of the cyclohexane oxime is less than 1 percent so as to remove salt ions in the cyclohexane oxime solution; mixing a water phase obtained after washing and a water phase obtained by extraction, and extracting the mixture by using a cyclohexane or hexane extractant in a weight part ratio of 0.5:1 at the temperature of between 45 and 55 DEG C so as to recycle the cyclohexane oxime in the mixture; and sequentially performing hydraulic cyclone separation and gravity settling separation on the washed organic phase when the mass concentration of the salt ions in the organic phase is less than 0.0001 percent so as to obtain the cyclohexane oxime. The process does not need a rectification process; the purity of the obtained cyclohexane oxime is high; beckmann rearrangement can be directly performed in the next process so as to prepare caprolactam; and for 100,000 t / a of cyclohexanone oxime devices, the process can save one-time equipment investment by about 20 to 30 million and can reduce energy consumption such as water, electricity, steam and the like by about 30 to 40 million.

Description

technical field [0001] The invention relates to a process for refining cyclohexanone oxime, which is further a process for refining an aqueous solution of cyclohexanone oxime through two-step extraction and washing. Background technique [0002] Cyclohexanone oxime is an isomer of caprolactam, and industrially generally use cyclohexanone oxime Beckmann rearrangement to produce caprolactam. In order to obtain high-quality caprolactam, the industry requires high purity of cyclohexanone oxime, generally requiring more than 99.9% (WT). To obtain high-purity cyclohexanone oxime, in addition to extracting and washing the aqueous solution of cyclohexanone oxime produced by the reaction, it is also necessary to carry out rectification regeneration of the extractant and rectification purification of cyclohexanone oxime. The increase of these processes, on the one hand, requires an increase in investment in disposable equipment, and more importantly, increases the regular operating c...

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Problems solved by technology

[0003] Chinese patent CN101781232A discloses a preparation process of cyclohexanone oxime. Although the refining process of cyclohexanone oxime has been simplified, because cyclohexanone oxime is changed from one step to two steps, and the second step is hydroxylamine oxime, this It will undoubtedly increase the difficulty and cost for enterprises without hydroxylamine preparation

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