Process for preparing caprolactam

Abstract

The invention discloses a process for preparing caprolactam, which comprises the following steps: after mixing cyclohexanone and cyclohexane evenly, carrying out an oxamidine reaction to obtain a cyclohexane solution of cyclohexanone oxime; enabling the cyclohexane solution of the cyclohexanone oxime and oleum to react to generate a caprolactam sulfate solution, curing the caprolactam sulfate solution, then carrying out a neutralization reaction on the cured caprolactam sulfate solution and ammonia, afterwards separating the two materials to obtain a crude product of caprolactam and then carrying out extraction and water back extraction respectively to prepare a finished product. Because of the existence of a cyclohexane inert solvent, rectification and separation do not need to be carried out after the oxamidine reaction, and only a rearrangement reaction needs to be carried out after the water phase of a catalyst is separated, thereby saving a rectification device and the steam consumption; as a result, a caprolactam enterprise with an annual yield of a hundred thousand tons can save energy worth approximately 60000000 yuan every year and can also save the one-off equipment investment totaling 60000000 yuan, the technological process of caprolactam is simplified, the procedures of water washing, extraction, distillation and the like are reduced, the production period is shortened, and the annual yield is enhanced.

Description

Technical field: [0001] The invention relates to a process for preparing caprolactam, in particular to a process for preparing caprolactam in the presence of a cyclohexane inert solvent. Background technique [0002] Caprolactam is the raw material for the production of nylon-6. At present, the preparation of caprolactam in the world mainly includes the ketone-hydroxylamine route using benzene as raw material, the amidation method of hexahydrobenzoic acid using toluene as raw material, and the direct preparation of caprolactam by photonitrosation of cyclohexane. [0003] Among them, the ketone-hydroxylamine route using benzene as raw material is the most, accounting for more than 90% of the total production capacity. [0004] The ketone-hydroxylamine route is divided into HSO method (hydroxylamine sulfate method), NO method (nitric oxide reduction method), and HPO method (hydroxylamine phosphate method) because of the different process routes of hydroxylamine. [0005] How...

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Problems solved by technology

[0005] However, the above three methods, whether it is HSO, NO or HPO method, all have long process and complicated process.

The main reason is that after each intermediate product (cyclohexanone, cyclohexanone oxime, caprolactam crude product) is prepared, there is a set of refining process of rectification and separation, which not only results in long process flow, large equipment investment, but also high energy consumption.

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