Method for removing small amount of acetic acid or methanoic acid and refining DMF

A technology of acetic acid and formic acid, applied in the chemical industry, can solve the problems such as hydrolysis of DMF, and achieve the effects of simplifying the operation process, reducing energy consumption, and improving economic value and social value.

Active Publication Date: 2017-06-13
FUZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] In the existing production of sucralose, alkali neutralization treatment is often used to remove acetic acid in DMF solution, but it is necessary to increase the solid treatment device, and DMF will be hydrolyzed under alkaline conditions

Method used

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  • Method for removing small amount of acetic acid or methanoic acid and refining DMF

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0038] process such as figure 1 As shown, a DMF solution containing 15% acetic acid, methanol with a molar ratio of 1:1 to acetic acid, and NKC-9 catalyst with 20% acetic acid weight were added to the pre-reactor, and the reaction temperature was 70°C.

[0039] After the pre-reaction, the mixed liquid is sent to the feed port of the upper section of the reactive distillation column, the ratio of the methanol feed flow rate at the lower end of the reactive distillation column to the mixed liquid feed flow rate at the upper section is 0.3:1, and the reactive distillation column is operated at normal pressure, with a theoretical plate number of 30 , the reflux ratio is 0.5, the top components are methyl acetate: 34.1%, methanol: 59.3%, water: 6.6%, and the bottom components are DMF: 98.9%, acetic acid: 0.1%, water: 1%.

[0040]The bottom component enters the DMF dehydration tower, the operating pressure is 20kPa, the number of theoretical plates is 20, the reflux ratio is 3, the ...

Embodiment 2

[0042] process such as figure 1 As shown, a DMF solution containing 30% acetic acid, methanol with a molar ratio of 2:1 to acetic acid, and NKC-9 catalyst with 15% acetic acid weight were added to the pre-reactor, and the reaction temperature was 65°C.

[0043] After the pre-reaction, the mixed liquid is sent to the feed port of the upper section of the reactive distillation column. The ratio of the methanol feed flow rate at the lower end of the reactive distillation column to the mixed liquid feed flow rate at the upper section is 0.4:1. The reactive distillation column is operated at normal pressure, and the number of theoretical plates is 30. , the reflux ratio is 0.5, the top components are methyl acetate: 34.1%, methanol: 59.7%, water: 6.2%, and the bottom components are DMF: 96.5%, acetic acid: 0.4%, water: 3.1%.

[0044] The bottom component enters the DMF dehydration tower, the operating pressure is 20kPa, the number of theoretical plates is 20, the reflux ratio is 2,...

Embodiment 3

[0046] process such as figure 1 As shown, a DMF solution containing 40% acetic acid, methanol with a molar ratio of 3:1 to acetic acid, and NKC-9 catalyst with 15% acetic acid weight were added to the pre-reactor, and the reaction temperature was 65°C.

[0047] After the pre-reaction, the mixed liquid is sent to the feed port of the upper section of the reactive distillation column. The ratio of the methanol feed flow rate at the lower end of the reactive distillation column to the mixed liquid feed flow rate at the upper section is 0.4:1. The reactive distillation column is operated at normal pressure, and the number of theoretical plates is 30. , the reflux ratio is 0.5, the top components are methyl acetate: 29.7%, methanol: 64.7%, water: 5.6%, and the bottom components are DMF: 95.4%, acetic acid: 0.4%, water: 4.2%.

[0048] The bottom component enters the DMF dehydration tower, the operating pressure is 20kPa, the number of theoretical plates is 20, the reflux ratio is 1....

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Abstract

The invention discloses a process method for separating DMF and acetic acid or methanoic acid in sucralose production. The process method comprises the following steps: adding methyl alcohol, a DMF mixed liquid containing acetic acid or methanoic acid, and a solid acid catalyst into a pre-reactor; entering a reaction rectification tower after pre-reaction; filling the reaction rectification tower with the solid acid catalyst; further reacting the acetic acid or methanoic acid which does not react with methyl alcohol in the reaction rectification tower; and feeding a mixture of methyl alcohol, water and methyl acetate or methyl formate at the top of the reaction rectification tower into an existing methyl ester and methyl alcohol separation device in sucralose production, feeding a mixture of DMF and water at the tower bottom into a DMF dehydration tower, and reclaiming at the tower bottom to obtain high-purity DMF. By adopting the method, the problem of separating the highest azeotrope DMF and acetic acid or methanoic acid in actual production can be solved, acetic acid is transformed into useful methyl acetate or methyl formate, the economic benefit is increased, the DMF having a purity more than 99 percent can be reclaimed, and the production cost is greatly reduced.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and specifically relates to the separation of N,N-dimethylformamide (DMF) and acetic acid or formic acid in the sucralose industry by means of reactive distillation. Background technique [0002] N,N-Dimethylformamide, referred to as DMF, is an aprotic polar solvent and an excellent solvent for many reactions. In the production of sucralose, a large amount of mixed solution of DMF and acetic acid will be produced, and DMF will be hydrolyzed into formic acid and dimethylamine. Since DMF, acetic acid and formic acid are all strongly polar substances, there is a strong interaction force between DMF and acetic acid or formic acid, and the highest azeotrope can be formed (the azeotropic temperature of DMF and acetic acid at normal pressure is 156 ° C, and the mass fraction of acetic acid is 27 %; DMF and formic acid have an atmospheric azeotropic temperature of 153°C and a mass fraction of ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C231/24C07C233/03
CPCC07C231/24C07C233/03Y02P20/10
Inventor 郑辉东张健文秦凯揭会民王莹淑
Owner FUZHOU UNIV
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