Preparation method of cyclohexanone-oxime

Abstract

The invention relates to a preparation method of cyclohexanone-oxime, which mainly comprises the following steps: (1) oxidizing cyclohexane and molecular oxygen under the action of a solid catalyst, carrying out one-step reaction to generate KA oil, and performing separation to obtain the KA oil; (2) directly aminating the KA oil with ammonia and hydrogen under the action of a solid catalyst to generate cyclohexylamine and a small amount of byproduct-A, and performing separation to obtain cyclohexylamine; (3) carrying out partial oxidation on cyclohexylamine and molecular oxygen under the action of a solid catalyst to obtain an oxidation product mainly composed of cyclohexanone-oxime, a small amount of byproduct-B and cyclohexylamine which may not be completely converted; and (4) aminatingthe oxidation product, namely, directly carrying out amination reaction on the oxidation product obtained in the step (3), ammonia and hydrogen under the action of a solid catalyst without separation, converting the byproduct-B into cyclohexylamine, and performing separation to obtain cyclohexanone-oxime. The method is short in technological process, small in occupied area and investment, low incost and environmentally friendly.

Description

technical field [0001] The invention relates to the preparation of cyclohexanone oxime, in particular to a preparation method of cyclohexanone oxime. Background technique [0002] Cyclohexanone oxime is an intermediate of ε-caprolactam, an important raw material (the main purpose is to produce polyamide chips through polymerization to further produce nylon fibers, engineering plastics, plastic films, etc.). [0003] Currently known cyclohexanone oxime production methods mainly contain two: cyclohexanone-hydroxylamine method and cyclohexanone ammoximation method. These two methods are the most commonly used, and both use benzene as the starting material to synthesize cyclohexanone oxime through the intermediate cyclohexanone. [0004] There are currently three industrial methods for synthesizing cyclohexanone from benzene: phenol method, cyclohexane oxidation method and cyclohexene hydration method. The phenol method has a long history. The earliest cyclohexanone oxime prod...

AI Technical Summary

Problems solved by technology

This method mainly has the following disadvantages: one is that the yield of phenol is low (72-75%), and there are many by-products; the other is that the separation and purification device of phenol and acetone is complicated and the energy consumption is high; Price affects the production cost of phenol

The main advantage of this method is that the complete hydrogenation of benzene to cyclohexane is a mature technology with low difficulty and high yield, but there are three major disadvantages in the oxidation process of cyclohexane: (i) In order to maintain a high selectivity, the cyclohexane The one-way cyclohexane conversion rate of hexane air oxidation can only be controlled at 3-5%, and a large amount of unconverted cyclohexane needs to consume a lot of energy to separate and circulate it. Even so, the final cyclohexane calculated The total yield of KA oil (a mixture of cyclohexanone and cyclohexanol) can only reach about 83%, which shows that the consumption of cyclohexane is high and the amount of by-products is large

(ii) The main product of the uncatalyzed oxidation reaction of cyclohexane is cyclohexyl hydroperoxide, and its decomposition process needs to consume NaOH. In addition, the by-products of the oxidation reaction of cyclohexane are mainly acids, esters, ethers, etc., which also need to pass Saponification and removal of alkaline aqueous solution requires the consumption of a large amount of NaOH and the generation of a large amount of saponification waste lye, not only the production cost is high, but also the environmental pressure is relatively high

(iii) Since the target product is cyclohexanone, it is necessary to further separate KA oil into cyclohexanone and cyclohexanol through rectification, and then dehydrogenate cyclohexanol into cyclohexanone; but due to the limitation of thermodynamic equilibrium, cyclohexanone The one-way conversion rate of hexanol dehydrogenation is generally less than 80%, so cyclohexanol and cyclohexanone must be separated after dehydrogenation, and the difference between the boiling points of cyclohexanone and cyclohexanol is only about 6°C, and the separation difficulty will lead to Higher energy consumption, plus the single-pass conversion rate of cyclohexane oxidation mentioned above is only 3-5%, so the energy consumption of the whole process is very high

[0006] To sum up, although the two-step method for producing cyclohexanone by oxidation of cyclohexane widely used in industry currently has a low technical threshold and is relatively mature, there are problems of "three highs and one big": high consumption of cyclohexane, high consumption of cyclohexane, Problems such as high alkali consumption, high energy consumption and large waste alkali treatment load

However, this method still has the following disadvantages: the one, because the cyclohexanol still adopts the cyclohexene hydration route to prepare cyclohexanol, so the problem of high energy consumption as mentioned above cannot be avoided; The oxidation reaction with cyclohexylamine will produce some by-products with boiling points close to or higher than the boiling point of cyclohexanone oxime. ℃ is very close, and the boiling point of dicyclohexylamine and N-cyclohexylcyclohexyl imine is higher than that of cyclohexanone oxime

Therefore, separating cyclohexanone oxime from these by-products with similar boiling points or higher boiling points is not only very difficult, but also requires a lot of energy

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