Production technology and equipment system for improving quality and yield of cyclohexanone oxime

Abstract

The invention discloses a production technology and equipment system for improving the quality and yield of cyclohexanone oxime. According to the production technology, special ammoximation conditionsare adopted, under the assistance of secondary oximation, the cyclohexanone oximation conversion rate is effectively increased without increasing the consumption amount of hydrogen peroxide, and theyield and quality of cyclohexanone oxime are improved. The equipment system comprises following components communicated by pipelines: a direct ammoximation reactor, a membrane separator, an organic solvent extraction column, and a secondary oximation reactor. The production technology and the structure of the equipment system are simple; the operation is safe; high quality cyclohexanone oxime canbe prepared, and the yield is high.

Description

technical field [0001] The invention belongs to the field of preparation of cyclohexanone oxime, in particular to a production process and equipment system for improving the quality and yield of cyclohexanone oxime. Background technique [0002] At present, caprolactam is mainly prepared from cyclohexanone oxime through Beckmann rearrangement and translocation. The main processes for preparing cyclohexanone oxime include Raschig method (hydroxylamine sulfate method), HPO method (hydroxylamine phosphate method), NO reduction method and direct ammonia Oximation method. The Raschig method uses cyclohexanone and hydroxylamine sulfate to carry out oximation reaction to obtain cyclohexanone oxime. Among them, hydroxylamine sulfate is prepared by reducing ammonium nitrite with sulfur dioxide. This process is very mature and is the earliest successful process route. However, due to the large amount of ammonium sulfate by-product, the quality of hydroxylamine sulfate obtained is ave...

AI Technical Summary

Problems solved by technology

Toluene, cyclohexanone and cyclohexyl imine are recovered from the top of the tower, and cyclohexanone oxime (purity 99%-99.5%) containing impurities such as dipolycyclohexyl imine and octahydrophenazine goes out from the tower kettle, and then Entering the Beckman rearrangement and translocation process may easily cause the volatile base index of subsequent caprolactam products to fail

Therefore, the conversion rate of cyclohexanone in the traditional direct ammoximation process is low, resulting in high unit consumption of cyclohexanone, and because cyclohexanone is converted into cyclohexyl imine, the polycyclic rings produced in the rectification process Substances such as hexylimine and swahydrophenazine lead to the poor quality of cyclohexanone oxime, which in turn leads to the quality of caprolactam not reaching the world-class level

Increasing the amount of hydrogen peroxide and ammonia in the oximation reaction can alleviate this problem to some extent, but excessive hydrogen peroxide is not stable, and ammonia will be oxidized to nitrogen oxides, which will pollute the environment. It increases the safety risk of industrial implementation, which is not in line with the current direction of my country's development of green and safe chemical industry

[0011] CN101781232A discloses a preparation process of cyclohexanone oxime, which combines two oximation reactions to solve the problem of incomplete conversion rate of cyclohexanone directly through ammoximation of cyclohexanone, but they also think that one-step oximation The conversion rate can reach or exceed 99.5%, and it is not recognized that the conversion rate of cyclohexanone oximation is actually low due to the existence of cyclohexyl imine

Moreover, in the second oximation reaction, although an excessive amount of aqueous solution of hydroxylamine sulfate was used, the pH was not adjusted simultaneously during the reaction, so that although the concentration of hydroxylamine salt in the reaction system was high, the actual part of the oximation reaction actually participated The concentration of free hydroxylamine is not high, and the sulfuric acid by-product of the oximation reaction is not neutralized in time, which will cause the system to become more and more acidic

Experiments have proved that under strong acidic conditions, this method cannot increase the conversion rate of oximation of cyclohexanone, but may lose cyclohexanone oxime, so that the secondary oximation of this process cannot increase the total cyclohexanone oxime transformation rate, so the patent has been in the unapplied stage

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