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Separation and purification method for solution containing N-methyl pyrrolidone (NMP)

A technology of methylpyrrolidone and purification method, which is applied in the field of solvent recovery, can solve the problems of high cost, low volatility, poor practicability, etc., and achieve the effect of low energy consumption and high recovery rate

Inactive Publication Date: 2011-07-06
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the extractants involved in this invention are all low-volatility or high-cost substances, and the practicability is relatively poor.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Prepare 75% (by weight) aqueous solution of N-methylpyrrolidone, take 4.2 grams and 29.3 grams of chloroform, mix well at room temperature, and let stand to separate layers. The refractive index of the water layer was measured with an Abbe refractometer, and the NMP content of the water layer was calculated to be 10% according to the refractive index-concentration curve.

Embodiment 2

[0026] Prepare 10% (by weight) aqueous solution of N-methylpyrrolidone, take 14.3 grams and 28.6 grams of chloroform, mix well at room temperature, and let stand to separate layers. The NMP content of the water layer was measured to be 3.5%.

Embodiment 3

[0028] Prepare 6.7 grams of 50% (by weight) aqueous solution of N-methylpyrrolidone, mix them well with 27 grams of chloroform at room temperature, and let them stand to separate into layers. The measured NMP content of the water layer was 10%.

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Abstract

The invention discloses a separation and purification method for the solution containing N-methyl pyrrolidone (NMP), which is applied to, the purification of NMP in aramid polymer powder washing mother liquor. The separation and purification method comprises the following steps: I, acidic solution containing NMP is neutralized, and the pH value of the solution is controlled between 5.5 and 7.0; II, chloroform as an extracting solvent is sufficiently mixed with neutral solution containing NMP at normal temperature according to the weight ratio of 1 to 8, then the mixed solution stands, and the fractional extraction in more than one stage is carried out; an aqueous solution containing inorganic salts is formed on the upper layer of a stratified solution system obtained after each stage of extraction, and chloroformic solution containing N-methyl pyrrolidone (NMP) is formed on the lower layer of the stratified solution system obtained after each stage of extraction; and III, the chloroformic solution containing NMP obtained through extraction and separation is purified by a rectification method. The extraction rate of NMP can reach more than 99 percent, the stratified solution of chloroform is rectified to obtain reusable NMP with purity higher than 99.95 percent, and the separation and purification method has the advantages of low energy conservation and high recovery ratio.

Description

technical field [0001] The invention relates to a separation and purification process of an N-methylpyrrolidone aqueous solution. The N-methylpyrrolidone solvent is mainly used in the process of preparing aramid by low-temperature polycondensation, and belongs to the field of solvent recovery. Background technique [0002] The low-temperature polycondensation method using N-methylpyrrolidone (abbreviated as NMP in English, hereinafter referred to as this abbreviation) as a solvent is currently the main synthesis method for commercial aramid fibers. Because the solvent is very expensive, it must be recycled, and the quality of the recovered solvent must meet the polymerization requirements, and the recovery rate must reach more than 95%. [0003] The aramid fiber polymer is post-treated by washing with water, and the obtained solution is a multi-component mixed system containing water, NMP, pyridine, inorganic salts, hydrochloric acid and other substances. Since calcium chlo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D207/267
Inventor 江志荣倪寒秋
Owner CHINA PETROLEUM & CHEM CORP
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