Recrystallization method of long-chain dicarboxylic acid

A long-chain dibasic acid, recrystallization technology, applied in the direction of crystallization separation, solution crystallization, separation method, etc., to achieve the effect of convenient subsequent transportation, small particle size, and improved solubility

Active Publication Date: 2021-05-04
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In order to solve the problems in the prior art that the product is easy to precipitate on the cold wall when the long-chain dibasic acid is cooled and crystallized, resulting in a decrease in cooling efficiency and low product yield, the present invention provides a method for recrystallization of the long-chain dibasic acid, using a specific solvent After the long-chain dibasic acid is dissolved, the long-chain dibasic acid starts to crystallize from the inside of the system during the decompression process, which solves the problem of crystal cold wall precipitation in the prior art

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0024] Take 2000 kg of crude dibasic acid dry powder, add 4000 kg of propyl ether and 200 kg of 5% (wt%) methanol to obtain 6200 kg of material to be treated, and the concentration of dibasic acid is 47.6g / 100g solvent. To the crystallizer, preheat to 80°C, stop heating and keep warm, close the tail gas vent valve, turn on the crystallizer to stir, open the tail gas vent valve, evacuate to 90kPa, and then maintain for 30 seconds, pump out 305kg (4.92%wt) of the material to be treated ) solvent, close the tail gas vent valve, add hot nitrogen to pressurize, keep the pressure at 150kPa, and at the same time start the program cooling, control the cooling rate at 16°C / h, stop at the crystallization end temperature of 20°C, and obtain the recrystallized dibasic acid. During the recrystallization process, the dibasic acid does not have the problem of cold wall precipitation, and the obtained grain size is uniform.

Embodiment 2

[0026] Take 2000kg of crude dibasic acid dry powder, add 6000kg of n-butyl ether and 30kg of 0.5% (wt%) ethanol to obtain 8030kg of material to be treated, and the concentration of dibasic acid is 33.2g / 100g solvent. To the crystallizer, preheat to 90°C, stop heating and keep warm, close the tail gas vent valve, turn on the crystallizer to stir, open the tail gas vent valve, evacuate to 80kPa, and then maintain for 15 seconds, pump out 41kg (0.51%wt) solvent, Close the tail gas vent valve, add hot nitrogen to pressurize, keep the pressure at 135kPa, and at the same time start the program cooling, control the cooling rate at 12°C / h, stop at the crystallization end temperature of 20°C, and obtain the recrystallized dibasic acid. During the recrystallization process, the dibasic acid does not have the problem of cold wall precipitation, and the obtained grain size is uniform.

Embodiment 3

[0028] Take 25g of crude dibasic acid dry powder, add 90g of n-pentyl ether and 9g of 10% (wt%) propanol to obtain 124g of material to be treated, and the concentration of dibasic acid is 25.3g / 100g solvent. Put into the crystallizer, preheat to 95°C, stop heating and keep warm, close the tail gas vent valve, turn on the crystallizer to stir, open the tail gas vent valve, evacuate to 70kPa, and then maintain for 10 seconds, pump out 3.05g (2.46%wt) solvent , close the tail gas venting valve, add hot nitrogen to pressurize, keep the pressure at 117kPa, and at the same time start the program cooling, control the cooling rate at 18°C / h, stop at the crystallization end temperature of 20°C, and obtain the recrystallized dibasic acid. During the recrystallization process, the dibasic acid does not have the problem of cold wall precipitation, and the obtained grain size is uniform.

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Abstract

The invention relates to a recrystallization method of long-chain dibasic acid, which comprises the following steps: by taking a mixed solution of ethers and at least one selected from water and low-carbon alcohol as a solvent of the long-chain dibasic acid and a to-be-treated material with the concentration of the long-chain dibasic acid in the to-be-treated material being 15-50g / 100g solvent, putting the to-be-treated material in a crystallizer, preserving heat at the temperature of 80-95 DEG C, reducing the pressure, keeping the vacuum degree, extracting part of the solvent to reduce the volume of the to-be-treated material by 0.5-10%, then increasing the pressure to maintain positive pressure, and cooling to crystallize and separate out the long-chain dibasic acid, thereby completing the recrystallization of the long-chain dibasic acid. According to the invention, seed crystals do not need to be added, the solubility of the dibasic acid can be greatly improved by adding the low-carbon alcohols, then the dibasic acid is discharged through pressure reduction, so that the solubility of the dibasic acid is greatly reduced, crystals are separated out, the dibasic acid explodes in a solvent to spontaneously nucleate in the subsequent cooling crystallization process, and compared with seed crystals added in an original process, the method has the advantages that the number of crystal nucleuses is larger, and the crystal tends to grow on a crystal nucleus rather than being separated out along a wall, so that the problem of cold wall separation is avoided.

Description

technical field [0001] The invention relates to the refining of long-chain dibasic acids, in particular to a recrystallization method of long-chain dibasic acids. Background technique [0002] The production methods of long-chain dibasic acids mainly include chemical synthesis and biological fermentation. Due to factors such as complex process, harsh conditions, low yield, and high cost, chemical synthesis has not been given priority. After years of development, the production of long-chain dibasic acids by biological fermentation is relatively mature. However, similar to the fermentation process of other chemicals, the process of extracting products from the fermentation broth is relatively complicated, and the cost of separation and purification of dibasic acids accounts for a large proportion of the production cost. The purification methods of dibasic acids mainly include aqueous phase method and solvent method, but with the continuous expansion of the application field ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01D9/02C07C51/43C07C55/02C07C57/13
CPCB01D9/00C07C51/43C07C55/02C07C57/13
Inventor 王鹏翔高大成朱化雷
Owner CHINA PETROLEUM & CHEM CORP
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