Recovery method of N-methyl pyrrolidone

A technology of methyl pyrrolidone and a recovery method, which is applied in the field of recovery of chemical raw materials, can solve the problems of difficult control of the rectification process, inability to apply on a large scale, low working temperature, etc., so as to eliminate the phenomenon of concentration polarization and improve the average operating temperature. , the effect of reducing pressure drop and temperature drop

Pending Publication Date: 2020-02-07
HYLEIN ENERGY & ENVIRONMENT TECH CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, lithium battery factories directly hand over the relevant waste liquid to third-party companies for treatment. The existing industrial technology uses rectification towers to recycle it. The high-purity NMP solvent obtained by this method is used in mass production, which requires a large investment and high energy consumption. , which is not conducive to the recovery of a small amount of NMP waste liquid. At the same time, due to the poor separation effect of NMP and water, the resulting wastewater seriously exceeds the standard and is likely to cause environmental pollution. Therefore, an environmentally friendly and energy-saving new method for processing and recycling NMP solvents is urgently needed.
[0003] The method for reclaiming NMP in the patent CN106220548A is to utilize two towers to carry out atmospheric distillation and recovery. The first stage is a distillation tower to obtain a 90% NMP solution, and then enters the product tower for rectification to obtain high-purity NMP. The recovery device of the method is complicated and takes up Large area, high energy consumption, not suitable for a small amount of NMP waste liquid treatment
[0004] The method described in the patent CN107382810A adopts double-tower rectification, and adopts vacuum rectification in the two-stage rectification tower respectively, but this process device is more complicated, occupies a large area, consumes a lot of energy, and is only beneficial to large-scale and large-scale batches production
[0005] The activated carbon and molecular sieves used in the patent CN101696182A are used to purify and recover NMP. The whole process seems simple, but the additional problems caused by molecular sieve regeneration energy consumption and waste gas are more complicated, and the overall energy consumption and environmental protection problems make this method useless. not recognized by the market
[0006] U.S. Patent US4965370 adds alkali metal or alkali metal salt to remove impurity metal ions in industrial-grade NMP, and obtains high-purity NMP through continuous fractional distillation, but this continuous rectification consumes a lot of energy, and the product quality is difficult to control, and The distillation process is difficult to control, which is not conducive to industrial production
[0007] Patent CN201010296568.4 discloses a method for recovering and purifying NMP using pervaporation membranes. This method is limited by the type of membrane, the working temperature is low, and the pressure on the permeate side is too low, which is not conducive to industrial application. Therefore, this patent is more More suitable for laboratory level but not for large-scale application

Method used

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  • Recovery method of N-methyl pyrrolidone

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Experimental program
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Effect test

Embodiment example 1

[0038] Implementation example 1. Add 500kg of water-containing 20% ​​(mass content, the same below) NMP aqueous solution into the circulation tank, turn on the heater to start heating the feed liquid, turn on the vacuum pump to collect the permeate side, condenser and permeate of the membrane pervaporation separator The tank is gradually evacuated to an absolute pressure of 0.1kPa-15KPa, the condensation temperature is controlled at about -30°C, and the circulation temperature is 130°C. The cost of membrane module treatment and vacuum system is as follows

[0039] Permeate side pressure / kpa Membrane capacity kg / h Vacuum system cost / Kw 0.1 110 60 2 100 5 5 95 4 10 60 2 15 50 2

Embodiment example 2

[0040] Implementation Case 2: Add 500kg water containing 20% ​​(mass content, the same below) NMP aqueous solution into the circulation tank, turn on the heater to start heating the feed liquid, turn on the vacuum pump to collect the permeate side, condenser and permeate of the membrane pervaporation separator The tank is gradually evacuated to an absolute pressure of 2KPa, the condensation temperature is controlled at about 7°C, and the circulation temperature is 70-160°C. The processing capacity of the membrane module and the qualified rate of product quality are as follows

[0041] temperature / ℃ Membrane capacity kg / h Rate of qualified products 70 50 100 (colorless) 100 65 100 (colorless) 130 100 99 (colorless yellowish) 150 183 98 (light yellow) 160 240 85 (red) 190 492 70 (dark red)

Embodiment example 3

[0042] Implementation Case 3: Add 500kg of water-containing 20% ​​(mass content, the same below) NMP aqueous solution into the circulation tank, turn on the heater to start heating the feed liquid, turn on the vacuum pump to collect the permeate side, condenser and permeate of the membrane pervaporation separator The tank is gradually evacuated to an absolute pressure of 2KPa, the condensation temperature is controlled at about 7°C, the circulation temperature is 130°C, and the flow rate of the membrane module is adjusted. The processing capacity of the membrane module is as follows:

[0043] Velocity m / s flow m3 / h Membrane capacity 0.15 3.49 45 0.4 9.29 60 0.5 11.63 98 0.8 18.61 101 1 23.26 101 1.6 37.21 101

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Abstract

The invention provides a recovery method of N-methyl pyrrolidone. The method is characterized by comprising the following steps: heating an N-methyl pyrrolidone material liquid with the water contentof 1-50 wt.% in a circulating tank to 30-190 DEG C; introducing the heated N-methyl pyrrolidone material liquid into a pervaporation membrane assembly to make water in the material liquid be separatedfrom the material liquid side of the pervaporation membrane and enter the permeation side, wherein the pervaporation membrane assembly comprises 1-3000 organic-inorganic or inorganic-organic hybrid membrane single-pass pipes or multi-pass pipes, an absolute pressure of the permeation side is set to be 100-15000 Pa, and a membrane feeding speed of the material liquid is set to be 0.15-1.6 m/s; after the material liquid passes through the pervaporation membrane assembly, making the material liquid on the material liquid side return to the circulating tank, and making the water on the permeationside be condensed and recovered; and performing circulation for multiple times on the material liquid in the circulating tank to obtain recovered N-methyl pyrrolidone.

Description

technical field [0001] The invention relates to the field of recovery of chemical raw materials, in particular to a recovery method of N-methylpyrrolidone. Background technique [0002] N-methylpyrrolidone (NMP for short) is widely used in petrochemical industry, plastic industry, pesticide, dyestuff, material and lithium battery manufacturing industry. Among them, it is widely used as a solvent in the manufacturing process of lithium battery positive electrodes, and NMP as a solvent is vaporized by hot air and then condensed and recovered. At present, lithium battery factories directly hand over the relevant waste liquid to third-party companies for treatment. The existing industrial technology uses rectification towers to recycle it. The high-purity NMP solvent obtained by this method is used in mass production, which requires a large investment and high energy consumption. , is not conducive to the recovery of a small amount of NMP waste liquid. At the same time, due to ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D207/267
CPCC07D207/267
Inventor 李安武熊春刚
Owner HYLEIN ENERGY & ENVIRONMENT TECH CO LTD
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