JP2006052163A - Method for producing oxime - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing an oxime by which the average chlorocyclohexane concentration in a photochemical reaction vessel can be diluted without changing the feed rate of cyclohexane to suppress the formation of chlorocaprolactam which is a product impurity and the quality of caprolactam can be improved without increasing the energy consumption in a step of recycling the cyclohexane. <P>SOLUTION: An aliphatic saturated hydrocarbon and nitrosyl chloride are introduced into the reaction vessel which can be irradiated with light to produce the oxime by a photochemical reaction. The produced oxime is separated and the unreacted liquid is then introduced into another reaction vessel that can be irradiated with light. Thereby, the photochemical reaction similar thereto is carried out. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing an oxime capable of diluting the average chlorocyclohexane concentration in a photochemical reaction tank, and as a result, suppressing the by-product of chlorcaprolactam, which is a product impurity, and improving the product quality of caprolactam. Is.

  Conventionally known methods for producing oxime include a method for producing cyclohexanone oxime in the production of caprolactam and a method for producing cyclododecanone oxime in the production of laurolactam. And as a manufacturing method of the said cyclohexanone oxime, the direct oxidation method which adds the hydroxylamine synthesize | combined from ammonia to cyclohexanone obtained by carrying out the air oxidation of cyclohexane, or the cyclohexane reacts with nitrosyl chloride by a photochemical reaction PNC (Photo-Nitrosation of Cyclohexane) method may be mentioned.

  In the PNC method, cyclohexanone oxime is produced by a photonitrosation reaction in which a mixed gas of nitrosyl chloride and hydrogen chloride is blown into a photochemical reaction tank filled with cyclohexane as a raw material, and gives light energy in the visible light region.

  Here, in the conventional PNC method, as shown in FIG. 2, in order to use light energy without loss, the 50 kW high-pressure sodium lamp 2 as the light source is immersed in the reaction solution charged in the photoreaction vessel 1. ing. Nitrosyl chloride is photodissociated at a wavelength (<759 nm) exceeding its binding energy (38 kcal / mol), and cyclohexanone oxime is generated by a one-step reaction as shown by the following formula (1).

  Since the produced cyclohexanone oxime can be separated by specific gravity difference without being dissolved in the raw material cyclohexane, it is continuously extracted from the bottom of the photoreaction tank 1 (Non-Patent Document 1) and recovered by the oxime separator 3, Unreacted cyclohexane is extracted from the photoreaction tank 1, and chlorocyclohexane formed as a by-product remains in the can and is discharged outside the system in a distillation column (not shown) in the cyclohexane recycling process.

  However, when a certain amount of cyclohexanone oxime is produced by the conventional PNC method, a certain amount of chlorocyclohexane is by-produced. Most of this by-produced chlorocyclohexane is extracted from the photoreactor 1 together with unreacted cyclohexane, and remains in the can in the distillation column in the cyclohexane recycling process. It becomes chlorocyclohexanone oxime by nitrosation reaction. This chlorocyclohexanone oxime undergoes a rearrangement reaction under a sulfuric acid catalyst in the Beckmann rearrangement step, which is the next step, and becomes chlorcaprolactam. Since chlorcaprolactam is a product impurity of caprolactam, it has been a cause of deterioration in product quality.

Therefore, in the conventional PNC method, in order to suppress the amount of chlorcaprolactam by-produced, it is necessary to increase the supply amount of the raw material cyclohexane to the photoreaction tank 1 to dilute the chlorocyclohexane concentration in the photochemical reaction tank. However, increasing the supply amount of the raw material cyclohexane increases the amount of unreacted cyclohexane extracted from the photoreactor 1, which increases the amount of energy consumed in the cyclohexane recycling process.
Hirohito Okino and Katsuhiko Suzuki, “Toray / ε-Caprolactam Process by PNC Method”, Chemical Engineering, Vol. 60, No. 8, p. 62-64 (1996)

  The present invention has been achieved as a result of studying the solution of the problems in the conventional PNC technology described above as an issue.

  Therefore, the object of the present invention is to dilute the average chlorocyclohexane concentration in the photochemical reaction tank without changing the supply amount of cyclohexane to the photochemical reaction tank, and as a result, suppress the byproduct of chlorcaprolactam, which is a product impurity. An object of the present invention is to provide a method for producing an oxime that can improve the quality of caprolactam without increasing the energy consumption in the recycling process of cyclohexane.

  In order to achieve the above object, according to the present invention, an aliphatic saturated hydrocarbon and nitrosyl chloride are introduced into a reaction vessel capable of light irradiation, an oxime is generated by a photochemical reaction, and the generated oxime is separated. An unreacted solution is introduced into another reaction tank capable of irradiating light, and a photochemical reaction similar to that described above is carried out.

In the oxime production method of the present invention,
The aliphatic saturated hydrocarbon is a cycloaliphatic saturated hydrocarbon;
The cycloaliphatic saturated hydrocarbon is cyclohexane or cyclododecane;
In addition, it is preferable to introduce the unreacted liquid into another reaction tank capable of irradiating light and repeat the process of performing the same photochemical reaction twice or more.

  According to the present invention, as will be described below, impurity by-product can be suppressed and lactam quality can be improved without increasing the energy consumption in the recycling step of the unreacted liquid. That is, since the quality of caprolactam can be improved without increasing the energy consumption in the cyclohexane recycling process, it is extremely useful for the industry that produces lactam as a nylon raw material.

  Hereinafter, the present invention will be described in more detail with reference to the drawings.

  FIG. 1 is a flowchart showing an example of an oxime production facility used in the present invention.

  As shown in FIG. 1, in the present invention, first, an aliphatic saturated hydrocarbon, specifically, a cyclic aliphatic saturated hydrocarbon, more specifically, cyclohexane or cyclododecane is added to the first photoreaction vessel 10. The oxime is generated by a chemical reaction by light irradiated from the light source lamp 20 immersed in the reaction tank 10 while nitrosyl chloride and hydrogen chloride are blown into the first light reaction tank 10.

  Subsequently, the oxime produced in the first photoreaction vessel 10 is separated by the oxime separator 30 and unreacted cyclohexane is introduced into another second photoreaction vessel 11 to carry out a photochemical reaction similar to the above, The oxime produced here is separated by the oxime separator 31.

  The chlorocyclohexane in the unreacted cyclohexane discharged from the oxime separator 31 following the second photoreaction tank 11 is usually discharged to the outside of the system in the residue of the can in the distillation column in the cyclohexane recycling process. 3 can be introduced into a photoreaction tank (not shown) and a photochemical reaction similar to the above can be carried out.

  According to the present invention, by multiplying the photoreaction tank as described above, the average chlorocyclohexane concentration in the photochemical reaction tank can be diluted without changing the amount of cyclohexane supplied to the photoreaction tank, As a result, the by-product of chlorcaprolactam, which is a product impurity, can be suppressed and the product quality of caprolactam can be improved.

The photoreaction tank used in the present invention is a reaction tank having a structure in which a reaction tank filled with a raw material is irradiated with light from an upper surface, a lower surface or a side surface, or light is irradiated from a light source lamp immersed in the raw material liquid. Usually, those having an internal volume of 50 to 150 m ³ are used.

The supply amount of cyclohexane to the photoreaction vessel is usually set to 2 to 8 T / H, and the blowing amount of nitrosyl chloride and hydrogen chloride is usually set to 2000 to 6000 Nm ³ / H.

  In the present invention, an unreacted liquid discharged from the second photoreaction tank is introduced into another reaction tank that can be irradiated with light, and the process of performing the same photochemical reaction may be repeated twice or more. preferable.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

[Example 1]
Light from a 50 kW high-pressure sodium lamp immersed in a first photoreaction vessel, in which a mixed gas of nitrosyl chloride and hydrogen chloride was blown into the first photoreaction vessel (internal volume: 150 m ³ ) filled with cyclohexane at 6000 Nm ³ / H. Cyclohexanone oxime was continuously produced by the reaction. The cyclohexanone oxime produced in the first photoreaction vessel was separated by an oxime separator, and unreacted cyclohexane was introduced into the second photoreaction vessel at the subsequent stage to carry out the same photochemical reaction. Here, the supply amount of cyclohexane was 13.6 T / H.

  Table 1 shows the measurement results of the chlorocyclohexane concentration in the first and second photoreaction tanks in this case and the chlorcaprolactam concentration in the crude caprolactam produced from the obtained oxime.

[Comparative Example 1]
In Example 1, the photochemical reaction tank was not divided into a first stage and a second stage, and the two tanks were arranged in parallel as shown in FIG. 2 to perform the photochemical reaction, and the cyclohexane supply amount was set to 7.3 T / H × 2 tanks. Except that, the oxime was produced in the same manner.

  Table 1 shows the measurement results of the chlorocyclohexane concentration in each photoreaction tank and the chlorcaprolactam concentration in the crude caprolactam produced from the obtained oxime.

  As is clear from the results in Table 1, in Example 1, the average chlorocyclohexane concentration in the photochemical reaction tank was decreased despite the decrease in the amount of cyclohexane supplied, and as a result, it was generated in the Beckmann rearrangement process, which is the next process. The chlorcaprolactam concentration in the crude caprolactam also decreased. The rate of decrease compared to Comparative Example 1 was almost equal to 12% in the average chlorocyclohexane concentration and 14% in the chlorcaprolactam concentration, and it can be judged that the byproduct of chlorcaprolactam could be suppressed by the decrease in the average chlorocyclohexane concentration.

  In addition, as a result of continuous operation for 7 months under the conditions of Example 1, the energy consumption in the cyclohexane recycling process was reduced by 8% compared to the operation under the conditions of Comparative Example 1.

  In conclusion, according to the present invention, it was possible to suppress by-product impurities and improve caprolactam quality without increasing the energy consumption in the cyclohexane recycling process.

  According to the present invention, byproduct of impurities can be suppressed and lactam quality can be improved without increasing the energy consumption in the recycling process of the unreacted liquid. That is, since the quality of caprolactam can be improved without increasing the energy consumption in the recycling process of cyclohexane, it can be effectively used in the industry for producing lactam as a nylon raw material.

It is a flowchart which shows an example of the manufacturing equipment of the oxime used by this invention. It is a flowchart which shows an example of the manufacturing equipment of the oxime used conventionally.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoreaction tank 2 Sodium lamp 3 Oxime separator 10 1st photoreaction tank 11 2nd photoreaction tank 20 Light source lamp 21 Light source lamp 30 Oxime separator 31 Oxime separator

Claims (4)

Aliphatic saturated hydrocarbons and nitrosyl chloride are introduced into a reactor that can be irradiated with light, and oximes are generated by photochemical reaction. After the generated oxime is separated, the unreacted liquid is then transferred to another reactor that can be irradiated with light. A method for producing an oxime, which is introduced and performs a photochemical reaction similar to that described above. The method for producing an oxime according to claim 1, wherein the aliphatic saturated hydrocarbon is a cycloaliphatic saturated hydrocarbon. The method for producing an oxime according to claim 2, wherein the cycloaliphatic saturated hydrocarbon is cyclohexane or cyclododecane. The oxime production according to any one of claims 1 to 3, wherein the step of introducing the unreacted liquid into another reaction tank capable of irradiating light and performing a similar photochemical reaction is repeated twice or more. Method.

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