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Method for fine purification of lactic acid

A technology of lactic acid and reactive distillation tower, which is applied in chemical instruments and methods, separation/purification of carboxylic acid compounds, preparation of carboxylate, etc., can solve problems such as high energy consumption and environmental pollution, and achieve low energy consumption and improved Product purity, the effect of high product purity

Inactive Publication Date: 2009-07-29
HEFEI UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In order to solve the problems of serious environmental pollution and high energy consumption in the traditional esterification-hydrolysis process using concentrated sulfuric acid as a catalyst, the present invention provides a new crude lactic acid refining process with low operating cost, environmental friendliness, high product purity and suitable for industrial production. process, a method of refining lactic acid

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] A method for refining lactic acid comprises the following process steps:

[0026] (1) Use crude lactic acid with a concentrated mass fraction of 85% after acid hydrolysis to remove bacteria, protein, and residual sugar through flocculation and precipitation as raw material, mix it with methanol, the molar ratio of methanol to lactic acid is 5:1, and pump it into hydrogen-type strong An acidic cation exchange resin column was used for esterification reaction at a reaction temperature of 80° C., and the flow rate was controlled so that the residence time of the reaction mixture in the resin column was 30 minutes to obtain an esterification mixture.

[0027] (2) Distill the esterification mixture under reduced pressure to obtain a mixture A of methyl lactate, water and methanol, and reclaim the distillation residue B.

[0028] (3) Recover the distillation residue B, filter, mix with crude lactic acid, and carry out the next esterification reaction.

[0029] (4) Mix the mi...

Embodiment 2

[0033] The crude lactic acid (mass fraction of lactic acid is ~85%) concentrated after acid hydrolysis after flocculation and precipitation is used as raw material, mixed with methanol (the molar ratio of methanol to lactic acid is 4:1), and pumped into Hydrogen type strongly acidic cation exchange resin column is used for esterification reaction. The reaction temperature is 85° C., and the flow rate is controlled so that the residence time of the reaction mixture in the resin column is 25 minutes. The esterified mixture was distilled under reduced pressure to obtain a mixture A of methyl lactate, water and methanol, and the distillation residue B was recovered. Mix the mixture A of methyl lactate, water and methanol with an appropriate amount of deionized water (control the molar ratio of water to ester to 26:1), pump it into another strong acidic cation exchange resin column, and carry out the hydrolysis reaction. The reaction temperature is 90°C and the flow rate is controll...

Embodiment 3

[0035]Use the crude lactic acid (mass fraction of lactic acid is 70%) concentrated after acid hydrolysis after flocculation and precipitation to remove bacteria, protein, and residual sugar as raw material, mix with methanol (the molar ratio of methanol to lactic acid is 2:1), and pump in hydrogen Type strong acidic cation exchange resin column for esterification reaction, the reaction temperature is 100°C, the flow rate is controlled so that the residence time of the reaction mixture in the resin column is 20min. The esterified mixture was distilled under reduced pressure to obtain a mixture A of methyl lactate, water and methanol, and the distillation residue B was recovered. Mix the mixture A of methyl lactate, water and methanol with an appropriate amount of deionized water (control the molar ratio of water to ester to 4:1), pump it into another strong acidic cation exchange resin column, and carry out the hydrolysis reaction. The reaction temperature is 100°C and the flow ...

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Abstract

The invention relates to a method for refining lactic acid by cation resin column bed catalysis and reactive rectification technology. The method solves the problems that the traditional esterification-hydrolysis technology uses concentrated sulfuric acid as a catalyst, thereby causing the environmental pollution, and high energy consumption, etc. Crude lactic acid after the pretreatment and concentration is subjected to the esterification reaction with methanol or ethanol by a cation resin column; then a mixture after the esterification reaction is subjected to reduced pressure distillation to obtain a mixture A of methyl lactate or ethyl ester, the methanol or the ethanol, water and the like and a distillation residue B; and B is mixed with the methanol or the ethanol and introduced into the cation resin column to take the esterification reaction. Subsequently, A is mixed with deionized water and introduced into the other cation resin column to be hydrolyzed to obtain a hydrolysis mixture C. The hydrolysis mixture C is introduced into a reaction rectifying tower to continue hydrolysis, the methanol or the ethanol is eluted from the top of the tower, lactic acid aqueous solution is obtained from a reboiler, and a high purity lactic acid product is obtained after concentration and can reach (Chinese and American) pharmacopoeia grade standard.

Description

technical field [0001] The invention relates to a method for producing high-purity lactic acid, in particular to a method for separating and refining lactic acid based on the esterification-hydrolysis reaction of lactic acid and lower alcohols by using cationic resin column bed catalysis and reactive distillation technology. Background technique [0002] Lactic acid is a common hydroxycarboxylic acid with a simple structure, which widely exists in the human body, animals, plants and microorganisms, and has important applications in food, medicine, feed, chemical and other fields. In recent years, with the development of polylactic acid and application, the demand for lactic acid is increasing. [0003] The production of lactic acid mainly includes chemical synthesis, enzymatic conversion and fermentation. The production process of fermentation method is green and environmentally friendly, the price of raw materials is low, and the optical purity of the product is high. It i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C59/08C07C51/493C07C51/44
CPCY02P20/10
Inventor 姜绍通刘模潘丽军郑志罗水忠吴学凤唐晓明
Owner HEFEI UNIV OF TECH
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