Method for refining and purifying caprolactam

A caprolactam and process water technology, which is applied in the field of caprolactam refining and purification, can solve the problems of difficulty in ensuring stable product quality, large discharge of ion exchange waste liquid, and high safety risk in the hydrogenation process, achieving improved safety and reduced production costs , the effect of reducing production costs

Active Publication Date: 2018-03-09
SHAANXI KEYUAN ENVIRONMENTAL PROTECTION & ENERGY SAVING TECH
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

Although this refining process can obtain high-purity caprolactam products, there are also problems such as long process, large investment, complicated process control, difficulty in ensuring stable product quality, high energy consumption, and large discharge of ion exchange waste liquid, resulting in high pressure on environmental protection. The relatively obvious shortcomings such as high safety risks in the hydrogen process, especially in order to avoid the loss of caprolactam in this refining process, the three-effect evaporation con...

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  • Method for refining and purifying caprolactam

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Embodiment 1

[0026] see figure 1 The schematic diagram of the process flow of the present invention provided, the preparation method of the present invention comprises the following steps:

[0027] (1) Primary crystallization and separation

[0028] Continuously add process water into the first-stage crystallization tank (stirring type) at a flow rate of 1kg / h, and at the same time continuously add the mixture at a flow rate of 80kg / h; the mass ratio of the raw material to the recycled material in the mixture is 1:1, and the raw material It is a caprolactam aqueous solution with a water content of 28% (wt) (feeding material for a benzene extraction tower in a caprolactam factory), and the recycle material is a water-containing 210ppm (wt) caprolactam liquid (from step 6 of the present invention). Control the temperature in the primary crystallization tank to be 27°C, the pressure to be normal pressure, the liquid level to be 55%, the pH value to be 11.5 (the pH regulator is an aqueous sod...

Embodiment 2

[0042] see figure 1 The schematic diagram of the process flow of the present invention provided, the preparation method of the present invention comprises the following steps:

[0043] (1) Primary crystallization and separation

[0044] Continuously add process water into the first-stage crystallization tank (stirring type) at a flow rate of 8kg / h, and at the same time continuously add the mixture at a flow rate of 80kg / h; the mass ratio of the raw material to the recycled material in the mixture is 2.5:1, and the raw material It is the caprolactam solution containing water 260ppm (wt) (the distillation raffinate of a certain caprolactam factory distillation unit), and the recycle material is the caprolactam liquid containing water 320ppm (wt) (from step 6 of the present invention). Control the temperature in the first-stage crystallization tank to be 26°C, the pressure to be normal pressure, the liquid level to be 57%, the pH to be 6.2 (the pH regulator is an aqueous solutio...

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Abstract

The invention discloses a method for refining and purifying caprolactam. Through crystallizing low-water-content crude caprolactam at a constant temperature, one part of caprolactam with high qualityis obtained, through crystallizing room-temperature-crystallization high-water-content mother liquor at a low temperature and then performing distillation, the other part of caprolactam with high quality is obtained, wherein the low-temperature-crystallization mother liquor is evaporated to obtain circulation materials which participate in constant-temperature crystallization. A constant-temperature and low-temperature combined crystallization way is adopted and is matched with distillation and evaporation processes to realize the efficient refining and purification of the caprolactam. The constant-temperature and low-temperature crystallization has the advantages of low energy consumption, small effluent discharge, lowered production cost and improved safety. The method has the advantagesof high product yield, short technical process and low equipment investment. No inorganic solvent is used, the process is simple, and production cost is greatly lowered. The obtained caprolactam hasgood quality, each index is superior to the standard of a national standard premium grade; three waste (waste gas, waste water, industrial residue) discharge amount is small, and environment pollutionis low.

Description

technical field [0001] The invention relates to a method for refining and purifying organic matter, in particular to a method for refining and purifying caprolactam. Background technique [0002] Caprolactam is an important organic chemical raw material. It is mainly used as a raw material for the production of polyamide 6 engineering plastics and polyamide 6 fibers. It can also be used for the production of antiplatelet drugs such as 6-aminocaproic acid and laurocaprolactone. It is very useful. widely. In the prior art, most manufacturers adopt the production route of converting cyclohexanone into cyclohexanone oxime, and then converting it into caprolactam through rearrangement. Due to the long route, the reaction is more complicated, accompanied by the occurrence of many side reactions, resulting in the presence of Various impurities. The fiber manufacturing industry has very high requirements on the purity of caprolactam, so it is necessary to remove as many impurities...

Claims

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Application Information

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IPC IPC(8): C07D223/10C07D201/16
CPCC07D201/16C07D223/10
Inventor 史永军杨诺张平安李峰史秦博苑
Owner SHAANXI KEYUAN ENVIRONMENTAL PROTECTION & ENERGY SAVING TECH
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