Method for extracting and recovering amide from aqueous solution

A compound solvent and amide recovery technology, applied in the separation/purification of carboxylic acid amide, organic chemistry, etc., can solve the problems of high solvent consumption, equipment corrosion, high energy consumption of separation, etc., to reduce solvent loss, reduce consumption, and improve distribution coefficient Effect

Active Publication Date: 2015-07-29
ZHEJIANG UNIV
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Problems solved by technology

[0003] In addition, although chloroform is a conventional solvent, due to its high-temperature instability, it is easy to decompose in the subsequent rectification and separation process and cause great corrosion to equipment.
Although dichloromethane is relatively stable and can also be used as an extractant, the distribution coefficient of amides is generally low. Compared with chloroform, the amount of solvent used is larger, which will greatly increase the cost of subsequent rectification and separation.
[0004] The present invention is based on the practical problems existing in the current industrial production, such as high solvent consumption and high subsequent separation energy consumption, and starts from improving the distribution coefficient of extraction and reducing the solvent consumption, and proposes a novel composite solvent extraction and recovery method for amide substances. method, which can improve the production process, reduce energy consumption and increase economic benefits in related fields

Method used

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  • Method for extracting and recovering amide from aqueous solution

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] as attached figure 1 As shown, the number of theoretical plates in the extraction tower 1 is 8, and the flow rate is 1000 kg / h containing N, N-dimethylacetamide 8% (wt%) aqueous solution is sent to the bottom of the extraction tower 1 at 30 ° C. The amide aqueous solution feed Port 22, main extractant dichloromethane is that 1200kg / h is sent into the top main extractant feed port 23 of extraction tower 1 at 30 ℃ with flow rate, and the composite solvent that dichloromethane and Virahol forms is 1200kg / h with flow rate h (containing isopropanol 30%) is sent into the composite solvent feed port 24 at the third theoretical plate from top to bottom of the extraction tower 1 at 30°C.

[0027] After sufficient liquid-liquid mass exchange in the extraction tower 1, the output of the raffinate phase at the top of the tower is 856.4kg / h, and the residual N,N-dimethylacetamide content is 0.25%; the output of the extraction phase at the bottom of the tower is It is 2543.6kg / h, an...

Embodiment 2

[0029] as attached figure 1 As shown, the number of theoretical plates in the extraction tower 1 is 8, and the flow rate is 1000 kg / h containing N, N-dimethylacetamide 25% (wt%) aqueous solution is sent to the bottom of the extraction tower 1 at 30 ° C. The amide aqueous solution feed Port 22, main extractant dichloromethane is that 1000kg / h is sent into the top main extractant feeding port 23 of extraction tower 1 at 30 ℃ with flow rate, and the composite solvent that dichloromethane and Virahol forms is 1500kg / h with flow rate h (containing isopropanol 20%) is sent into the composite solvent feed port 24 at the third theoretical plate from top to bottom of the extraction tower 1 at 30°C.

[0030] After sufficient liquid-liquid mass exchange in the extraction tower 1, the output of the raffinate phase at the top of the tower is 588.1kg / h, and the residual N,N-dimethylacetamide content is 0.50%; the output of the extraction phase at the bottom of the tower is It is 2344.5kg / h...

Embodiment 3

[0032] as attached figure 1 Shown, extraction tower 1 theoretical plate number is 8, and flow rate is the amide aqueous solution inlet 22 of the bottom that contains N-methylpyrrolidone 20% (wt%) that flow rate is sent into extraction tower 1 at 30 ℃, main Extractant dichloromethane is that 1500kg / h is sent into the top main extractant inlet 23 of extraction tower 1 at 30 ℃ with flow rate, and the composite solvent that dichloromethane and isobutanol forms is 1200kg / h (containing isobutanol) with flow rate Butanol 40%) is sent into the composite solvent feed port 24 of the 3rd theoretical plate place from top to bottom of extraction column 1 at 30 ℃.

[0033] After the sufficient liquid-liquid mass exchange of the extraction tower 1, the output of the raffinate phase at the top of the tower is 754.3kg / h, wherein the residual N-methylpyrrolidone content is 0.14%; the output of the extraction phase at the bottom of the tower is 2945.7kg / h h, wherein the N-methylpyrrolidone cont...

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Abstract

The invention discloses a method for extracting and recovering amide from an aqueous solution. An amide aqueous solution is added into the bottom of an extraction tower at a normal temperature, a main extraction agent is added into the top of the extraction tower, a composite solvent consisting of a main extraction agent and an auxiliary extraction agent is added into a part at the height, 0.1-0.4 times away from the top of the tower, of the extraction tower, extraction and separation are finished through countercurrent contact of liquid-liquid phases, and a raffinate phase mainly containing water and an extraction phase containing amide are obtained from the top and bottom of the tower respectively. The extraction phase containing amide passes through a main extraction agent recovery tower, an auxiliary extraction agent recovery tower and a product recovery tower in sequence to obtain the main extraction agent, the auxiliary extraction agent and an amide product from the top of the tower respectively, and the main extraction agent and the auxiliary extraction agent are recirculated for extraction of the amide aqueous solution. The method increases the distribution coefficient of amide in the extraction agent under the action of the auxiliary extraction agent, and can remarkably reduce the consumption of the extraction agent, reduce the energy consumption of subsequent rectification separation, so as to achieve remarkable economic benefits.

Description

technical field [0001] The invention relates to a method for extracting and recovering amide from an aqueous solution by using a composite solvent, in particular to a continuous production method for recovering and purifying amide from an aqueous solution of amide in the fields of chemical fiber and pharmaceuticals using amide substances as solvents in the production process. Background technique [0002] Amides are a class of highly polar chemical substances commonly used in chemical production. Representative products include N,N-dimethylacetamide, N,N-dimethylformamide and N-methylpyrrolidone. Chemical fiber, pharmaceutical and other fields are widely used as solvents. Because the boiling point of such substances is generally high, and the concentration in the aqueous solution is not high, conventional rectification separation and purification methods have disadvantages such as high energy consumption and difficulty in guaranteeing product purity. The current alternative...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C233/05C07C233/03C07C231/24C07D207/267
Inventor 王成习
Owner ZHEJIANG UNIV
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