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Method for separating mixed crystals of glycine and ammonium chloride

A technology of glycine and mixed crystals, applied in chemical instruments and methods, preparation of organic compounds, ammonium halide and other directions, can solve the problems of low yield of glycine, flammable methanol, low purity, etc., and achieve good economic benefits and savings Process cost, environmental pollution-free effect

Inactive Publication Date: 2014-12-10
INST OF PROCESS ENG CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But, methanol separation method has the following problems: (1) glycine yield is low and the purity is not high; (2) evaporation recovery methanol energy consumption is high; (3) methanol is flammable and volatile, and will Harmful to the human body; (4) the remaining waste water after recycling the ammonium chloride contains a certain amount of aminoacetic acid and urotropine, and the direct discharge of waste water not only wastes resources but also causes serious pollution to the environment
Although the author has selected ethylene glycol with less volatility to implement the separation of glycine and ammonium chloride to make the operation process safer, the yields of glycine and ammonium chloride obtained are all low and the purity is not high. And the operating temperature for separating ammonium chloride from ethylene glycol is too low, and the energy consumption is very large

Method used

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  • Method for separating mixed crystals of glycine and ammonium chloride
  • Method for separating mixed crystals of glycine and ammonium chloride
  • Method for separating mixed crystals of glycine and ammonium chloride

Examples

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Effect test

Embodiment 1

[0042] 500g of mixed crystals containing 60wt% glycine, 39wt% ammonium chloride and 1wt% water were placed in the crystallization tank I, and 1.3L ethylene glycol solution was added, while the stirrer was turned on and the temperature was controlled at 70°C. After 2 hours, the crystal slurry was taken out, and 255 g of aminoacetic acid was obtained after filtration and drying, and its purity was 99.6%. The filtrate was cooled to 15°C, and mixed crystals were precipitated. After filtering, 230 g of mixed crystals were obtained, and the mother liquor of ethylene glycol could be returned for use. The mixed crystals were dissolved in 400 mL of water at 70°C, and then the obtained mixed solution was placed in the crystallization tank II, and the temperature was lowered to 15°C to precipitate ammonium chloride crystals. After 2 hours, the magma was filtered, and the solid was dried to obtain 170g of ammonium chloride with a purity of 99.2%, and the filtrate was returned to be mixed...

Embodiment 2

[0044] Contain 48wt% glycine, 500g of mixed crystals of 50wt% ammonium chloride and 2wt% water are placed in crystallization tank I, add 1.5L propylene glycol solution, open agitator simultaneously and temperature is controlled at 80 ℃. After 2 hours, the crystal slurry was taken out, filtered and dried to obtain 200 g of aminoacetic acid with a purity of 99.7%. The filtrate was cooled to 10°C, and mixed crystals were precipitated. Obtain 255g of mixed crystals after filtration, and the propylene glycol mother liquor can be returned for use. The mixed crystals were dissolved in 500 mL of water at 70°C, and the obtained mixed solution was placed in the crystallization tank II, and the temperature was lowered to 10°C to precipitate ammonium chloride crystals. After 2 hours, the magma was filtered, and the solid was dried to obtain 230 g of ammonium chloride with a purity of 99.1%, and the filtrate was returned to be mixed with the raw material.

Embodiment 3

[0046] 500g of mixed crystals containing 45wt% glycine, 54wt% ammonium chloride and 1wt% water were placed in the crystallization tank I, and 1.8L of butanediol solution was added, while the stirrer was turned on and the temperature was controlled at 60°C. After 2 hours, the crystal slurry was taken out, filtered and dried to obtain 170 g of aminoacetic acid with a purity of 99.5%. The filtrate was cooled to 15°C, and mixed crystals were precipitated. Obtain 300g of mixed crystals after filtration, and the butanediol mother liquor can be returned for use. The mixed crystals were dissolved in 600 mL of water at 65°C, and then the obtained mixed solution was placed in the crystallization tank II, and the temperature was lowered to 10°C to precipitate ammonium chloride crystals. After 2 hours, the magma was filtered, and the solid was dried to obtain 245g of ammonium chloride with a purity of 99.2%, and the filtrate was returned to be mixed with the raw material.

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Abstract

The invention provides a method for separating mixed crystals of glycine and ammonium chloride. According to the method, the mixed crystals of glycine and ammonium chloride are separated by two-step crystallization respectively by using a glycol solvent and a water solution as media, so as to obtain a glycine product with high purity and a by-product ammonium chloride. According to the method, based on good use of the difference between glycine and ammonium chloride in solubility in the glycol solvent and the water solution, glycine and ammonium chloride are separated under the mild operation condition; the used glycol solvent is small in volatility, free of damage in an operation process, and easy to recover, the problems of methyl alcohol volatilization, high energy consumption in evaporation recovery and the like in the methyl alcohol separation process are overcome, and the separation reagent in the whole technical process is recycled, so that the production cost is saved and non-pollution emission is achieved.

Description

technical field [0001] The invention belongs to the field of separation and purification of aminoacetic acid, in particular to a method for separating mixed crystals of aminoacetic acid and ammonium chloride through two-step crystallization. Background technique [0002] Glycine, also known as glycine, has the molecular formula NH 2 CH 2 COOH is the simplest amino acid in structure. Solid glycine is odorless, non-toxic, white crystal with sweet taste. Glycine is widely used in the fields of food, medicine, agriculture and chemical industry, among which more than 90% of domestic Glycine is used to synthesize the herbicide glyphosate and the plant growth regulator glyphosate. [0003] The industrial synthesis methods of aminoacetic acid mainly include the Strecker method and the ammonolysis method of chloroacetic acid. The Strecker method uses sodium cyanide, formaldehyde, ammonium chloride and glacial acetic acid as raw materials, and is widely used in the United States, ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C229/08C07C227/42C01C1/16
Inventor 李志宝曾艳
Owner INST OF PROCESS ENG CHINESE ACAD OF SCI
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