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Caprolactam refining method

A technology of caprolactam and a refining method, which is applied in the refining field of caprolactam, can solve the problems of complicated process flow, inability to take into account product quality and yield, poor economy and the like, and achieves the effects of high purity, improved yield and reduced efflux.

Active Publication Date: 2019-05-07
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The object of the present invention is to provide a kind of refining method of caprolactam in order to overcome the defect that the prior art cannot take into account the product quality and yield, and the technical process is complicated, and the economy is poor. The method provided by the present invention can obtain the high-grade product caprolactam, And the weight removal step is omitted, the technological process is simple, and it is easy for industrial implementation

Method used

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Examples

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Embodiment approach

[0026] According to a preferred embodiment of the present invention, the conditions of the vacuum distillation include: a pressure of 0.3-2kPa, a temperature of 50-170°C, and a top reflux ratio of 1:(10-50). The pressures mentioned are absolute pressures.

[0027] According to the present invention, the variable temperature and pressure conditions refer to the gradual increase and decrease of temperature and pressure, and the variable temperature and pressure conditions can also stay at a certain temperature point or a certain pressure point for a period of time, but do not include temperature and pressure. The operation of high and low pressure.

[0028]Since caprolactam is a heat-sensitive substance, the residence time should be as short as possible under high temperature conditions. In addition, in the vacuum distillation process, the loss of caprolactam should be reduced as much as possible. The impurities with lower boiling point (less than 150°C) in the product are remo...

Embodiment 1

[0092] (1) Preparation of the crude product of caprolactam: get 785g of cyclohexanone oxime and carry out the crude caprolactam obtained by gas-phase Beckmann rearrangement reaction, utilize rotary evaporator to carry out solvent (methanol) recovery, obtain 303.5g containing the impurity that boiling point is higher than caprolactam and The caprolactam crude product of the impurity with lower boiling point than caprolactam, the caprolactam crude product is analyzed, and it is known that its main composition is: 95.8% by weight of caprolactam, 4840 μg / g of 5-cyano-1-pentene, 57 μg / g of cyclic Hexanone oxime, cyclohexenone at 4844 μg / g, octahydrophenazine at 386 μg / g, tetrahydroazepin-2-one and its isomers at 132 μg / g, decahydrophene at 1040 μg / g Oxyzine and other unidentified impurities.

[0093] (2) Remove light impurities: Distill the crude product of caprolactam under reduced pressure. Under the pressure (absolute pressure) of 1.3kPa, the temperature is heated from room temp...

Embodiment 2

[0103] (1) Preparation of caprolactam crude product: same as Example 1.

[0104] (2) Remove light impurities: Distill the crude product of caprolactam under reduced pressure, the pressure (absolute pressure) is 1.7kPa, the temperature is heated from room temperature (20°C) at 3°C / min to 90°C for 40min, there is no reflux at the top of the tower, Then the temperature was raised to 160°C at a rate of 3°C / min, the pressure was directly reduced to 0.35kPa, and the top reflux ratio was 1:40, until no light components were distilled out, and 265.8g of light-removed product (bottom material) was obtained. Chromatographic analysis of its main components: 98.9% by weight of caprolactam, 190 μg / g of 5-cyano-1-pentene, 205 μg / g of cyclohexanone oxime, 1023 μg / g of cyclohexenone, 440 μg / g of octahydro Phenazine, 210 μg / g tetrahydroazepin-2-one and its isomers and 1182 μg / g decahydrophenazine.

[0105] (3) Carry out crystallization and refinement according to the method of Example 1. The ...

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Abstract

The invention relates to the field of caprolactam production, and discloses a caprolactam refining method. The method comprises the following steps: (1) reduced pressure distillation is carried out ona caprolactam crude product containing impurities with a boiling point higher than the boiling point of caprolactam and impurities with a boiling point lower than the boiling point of caprolactam, sothat impurities with the boiling point lower than he boiling point of caprolactam is removed, and a light removed product is obtained; (2) the light removed product is mixed with a crystallization solvent, and then crystallizing is carried out to obtain a crystal; and (3) a hydrogenation reaction is carried out on the crystal, wherein the reduced pressure distillation is carried out under a condition of variable temperature and variable pressure, and the mass ratio of the crystallization solvent to the light removed product is (0.2-5):1. Premium-grade caprolactam can be obtained through the method provided by the invention, a heavy removal step is omitted, the process flow is simple, and the method is easy for industrial implementation.

Description

technical field [0001] The invention relates to the field of caprolactam production, in particular to a method for refining caprolactam. Background technique [0002] Caprolactam is one of the important raw materials for synthetic fibers and synthetic resins, mainly used in the manufacture of polyamide fibers (nylon 6), resins and films. The known production methods of caprolactam include cyclohexanone oxime liquid-phase Beckmann rearrangement method using oleum as catalyst, cyclohexanone oxime gas-phase Beckmann rearrangement method using solid zeolite as catalyst, and methods such as depolymerization of waste polymers. . The gas-phase Beckmann rearrangement reaction of cyclohexanone oxime on solid acid catalyst is a new process to realize the sulfur-free ammonization of caprolactam, which has the problems of no equipment corrosion and no environmental pollution, and the separation and purification of products will be greatly simplified, so no sulfur The new gas-phase Bec...

Claims

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Application Information

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IPC IPC(8): C07D223/10C07D201/16
Inventor 谢丽程时标张树忠王皓范瑛琦慕旭宏
Owner CHINA PETROLEUM & CHEM CORP
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