Method for recycling tetrahydrofuran in tetrahydrofuran-methanol-water by single-tower extractive distillation

A technology of tetrahydrofuran and extractive distillation, which is applied in the direction of extractive distillation, chemical instruments and methods, and the preparation of organic compounds, can solve the problems of complex process, high energy consumption, complex process, etc., and achieve simple and easy process and realize recovery Effects of reusing and reducing separation costs

Active Publication Date: 2016-09-28
QINGDAO UNIV OF SCI & TECH
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Problems solved by technology

There are two sets of azeotropes in this ternary mixture, which cannot be effectively separated by ordinary distillation methods.
[0004] The literature (Research on a new method for the separation of methanol-tetrahydrofuran-water system. Journal of Yantai University, Volume 14, No. 3, 2001) has studied a method for separating the ternary system using water and potassium fluoride. The method uses two Tower to achieve separation, the process is more complicated, and has not yet achieved industrialization
[0005] The patent (CN1660828A) relates to a method for recovering tetrahydrofuran from pharmaceutical waste liquid. The pharmaceutical waste liquid mainly contains THF, ethanol and water. Potassium oxide is stirred and then left to stand to obtain relatively pure tetrahydrofuran. The process is complicated, and it can be seen from its implementation cases that the process is currently in the laboratory research stage and has not yet been industrialized.
[0006] The patent (CN102911139A) relates to a solvent recovery and separation method containing THF-methanol system, using ethylene glycol as the extraction agent, and using the double-tower separation process of the extractive distillation tower and the extraction agent recovery tower to separate tetrahydrofuran and methanol azeotrope, the process is relatively Complex, does not involve the separation of tetrahydrofuran-methanol-water ternary system
[0007] The patent (CN104447636A) relates to the method and device for extracting and rectifying ethanol-tetrahydrofuran separation using a dividing wall column. The method uses 1,4-butanediol as the extraction agent and realizes the separation of ethanol-tetrahydrofuran azeotrope by using a single column. Separation, but does not involve the separation of ternary components. In addition, the operation of the dividing wall column is more complicated
[0008] The patent (CN104098431A) involves the extraction and rectification process of methanol, dichloromethane and water. The separation of methanol and dichloromethane is realized by using double towers. The process is complicated and the energy consumption is high

Method used

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  • Method for recycling tetrahydrofuran in tetrahydrofuran-methanol-water by single-tower extractive distillation

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035]The feed flow rate of tetrahydrofuran-methanol-water mixed liquid is 1400kg / h, normal temperature, pressure 1atm, mass composition: tetrahydrofuran 75%, methanol 6%, water 19%. The feed flow ratio of extractant to tetrahydrofuran-methanol-water mixture is 3.5:1. The operating pressure of extractive distillation column C1 is 1 atm, the reflux ratio is 1, the number of trays is 18, the mixed liquid feeding plate is the 12th plate, the extractant feeding plate is the 12th plate, and the tower top temperature is 32.9°C , the temperature at the bottom of the tower is 64.5°C. The extractant is 2-methyl-2-butene, and after being separated by extractive distillation column C1, the purity of tetrahydrofuran extracted from the bottom of the column is 99.5%, and the yield is 99.7%. In the phase separator U3, after phase separation, the purity of the organic phase extraction agent 2-methyl-2-butene extracted from the upper layer is 99.6%, and it is transported to the mixing tank U1...

Embodiment 2

[0037] The feed flow rate of tetrahydrofuran-methanol-water mixed liquid is 1320kg / h, normal temperature, pressure 2atm, mass composition: tetrahydrofuran 80%, methanol 12%, water 8%. The feed flow ratio of extractant to tetrahydrofuran-methanol-water mixture is 2:1. The operating pressure of extractive distillation column C1 is 2atm, the reflux ratio is 0.8, the number of trays is 35 plates, the mixed liquid feeding plate is the 18th plate, the extractant feeding plate is the 18th plate, and the tower top temperature is 53.8°C , the temperature at the bottom of the tower is 89°C. The extractant is 2-methyl-2-butene, and after being separated by extractive distillation column C1, the purity of tetrahydrofuran extracted from the bottom of the column is 99.8%, and the yield is 99.5%. In the phase separator U3, after phase separation, the purity of the organic phase extraction agent 2-methyl-2-butene extracted from the upper layer is 99.7%, and it is transported to the mixing ta...

Embodiment 3

[0039] The feed flow rate of tetrahydrofuran-methanol-water mixed liquid is 1480kg / h, normal temperature, pressure 1.5atm, mass composition: tetrahydrofuran 78%, methanol 9%, water 13%. The feed flow ratio of extractant to tetrahydrofuran-methanol-water mixture is 4:1. The operating pressure of extractive distillation column C1 is 1.5atm, the reflux ratio is 1.5, the number of trays is 25 plates, the mixed liquid feed plate is the 16th plate, the extractant feed plate is the 16th plate, and the tower top temperature is 46.1 °C, the temperature at the bottom of the tower was 79 °C. The extractant is 2-methyl-2-butene, and after being separated by extractive distillation column C1, the purity of tetrahydrofuran extracted from the bottom of the column is 99.7%, and the yield is 99.6%. In the phase separator U3, after phase separation, the purity of the organic phase extraction agent 2-methyl-2-butene extracted from the upper layer is 99.8%, and it is transported to the mixing ta...

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Abstract

The invention provides a method for recycling tetrahydrofuran in tetrahydrofuran-methanol-water by single-tower extractive distillation, aiming at a current situation that two groups of azeotropes (namely tetrahydrofuran-methanol and tetrahydrofuran-water) in a tetrahydrofuran-methanol-water ternary mixture are difficult to separate. The method takes 2-methyl-2-butene as an extracting agent and realizes a target of recycling the high-purity tetrahydrofuran from the ternary mixture by utilizing the characteristic that the 2-methyl-2-butene, methanol and water form the lowest azeotrope. By adopting single-tower extractive distillation operation, compared with a traditional separation method, the energy consumption is greatly reduced and equipment cost is reduced. The extracting agent 2-methyl-2-butene is not dissolved in the water, so that high-purity recycling is realized; the extracting agent can be recycled to an extractive distillation tower and the cost of the raw materials is reduced.

Description

【Technical field】 [0001] The invention belongs to the field of chemical separation and purification, in particular to a method for recovering tetrahydrofuran-methanol-water tetrahydrofuran through single-tower extraction and rectification. 【Background technique】 [0002] Tetrahydrofuran is an important raw material for organic synthesis and a solvent with excellent performance. It is especially suitable for dissolving PVC, polyvinylidene chloride and butylaniline. It is widely used as a solvent for surface coatings, anti-corrosion coatings, printing inks, tapes and film coatings. As a reaction solvent, the thickness of the aluminum layer can be controlled arbitrarily when used in the electroplating aluminum solution. Methanol, with a boiling point of 64.5°C, is mainly used as a solvent for paints, inks, dyes, cellulose acetate, etc. It can also be used as a raw material for pesticides, medicines, and plastics. [0003] In the production process of steroid drugs in the pharm...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D307/08C07C31/04C07C29/84B01D3/40
CPCB01D3/40C07C29/84C07D307/08C07C31/04Y02P20/10
Inventor 朱兆友李鑫马艺心许希彩王英龙
Owner QINGDAO UNIV OF SCI & TECH
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