A method for purifying dehydroacetic acid

A technology of dehydroacetic acid and melting crystallizer, which is applied in the direction of organic chemistry, can solve the problems of poor control of cooling temperature, equipment needs to be improved, and low yield, so as to achieve good selectivity and safety of parallel reactions, reduce costs and The effect of equipment investment and quality stability

Active Publication Date: 2015-11-25
NANTONG ALCHEMY BIOTECH DEV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the equipment for large-scale production of dehydroacetic acid at home and abroad is a general enamel reaction kettle. The mature process of the process is as follows: that is, toluene and diketene are condensed under the action of a catalyst, and then the enamel kettle is cooled and crystallized, dehydrated, Finished products are obtained through drying, packaging and other processes. However, due to the poor control of the cooling temperature of the enamel kettle, the material is easy to stick, the yield is not high, the purity is greatly affected, and the appearance is very bad.
Therefore existing technique and equipment of this dehydroacetic acid need to be improved

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] The process of purifying dehydroacetic acid by melting crystallizer is as follows:

[0015] (1) Crystallization: first pass -8°C calcium chloride solution at the bottom of the outer jacket of the melting crystallizer, and the calcium chloride solution flows uniformly on the outer wall of the melting crystallizer as a falling film, and then put the condensed dehydroacetic acid solution into into the melting crystallizer, while passing through the melting crystallizer air duct at a distance of 4m 3 Inject compressed air into the dehydroacetic acid solution at a speed of 1 / min, so that it forms a slug-like flow bubble rising in the crystallization tube, causing turbulence of the melt, enhancing mass transfer and heat transfer performance, and the dehydroacetic acid solution is on the inner wall of the crystallizer The falling film flows down, gradually cools and crystallizes, and gradually grows a uniform crystal layer on the heat exchange surface. The concentration of the...

Embodiment 2

[0018] The process of purifying dehydroacetic acid by melting crystallizer is as follows:

[0019] (1) Crystallization: first pass -6°C sodium chloride solution at the bottom of the outer jacket of the melting crystallizer, and the sodium chloride solution flows uniformly on the outer wall of the crystallizer as a falling film, and then put the condensed dehydroacetic acid solution into the In the melting crystallizer, at the same time through the melting crystallizer air duct at a distance of 5m 3 Inject compressed air into the dehydroacetic acid solution at a speed of 1 / min, so that it forms a slug-like flow bubble rising in the crystallization tube, causing turbulence of the melt, enhancing mass transfer and heat transfer performance, and the dehydroacetic acid solution is on the inner wall of the crystallizer The falling film flows down, gradually cools and crystallizes, and gradually grows a uniform crystal layer on the heat exchange surface. The concentration of the crys...

Embodiment 3

[0022] The process of purifying dehydroacetic acid by melting crystallizer is as follows:

[0023] (1) Crystallization: first pass calcium chloride solution at -2°C at the bottom of the outer jacket of the melting crystallizer, the calcium chloride solution flows uniformly on the outer wall of the melting crystallizer in a falling film, and then the condensed dehydroacetic acid solution Throw it into the melting crystallizer, and at the same time pass through the melting crystallizer air duct at a distance of 7m 3 Inject compressed air into the dehydroacetic acid solution at a speed of 1 / min, so that it forms a slug-like flow bubble rising in the crystallization tube, causing turbulence of the melt, enhancing mass transfer and heat transfer performance, and the dehydroacetic acid solution is on the inner wall of the crystallizer The falling film flows down, gradually cools and crystallizes, and gradually grows a uniform crystal layer on the heat exchange surface. The concentra...

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PUM

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Abstract

The invention discloses a production process for preparing high-purity dehydroacetic acid by virtue of a melt crystallizer. The production process comprises the following steps: introducing freezing saline water into the bottom of a jacket of the melt crystallizer, enabling the freezing saline water to uniformly flow at the outer wall of the crystallizer in a falling film manner, putting a condensed dehydroacetic acid solution into the melt crystallizer, enabling the condensed dehydroacetic acid solution to flow down at the inner wall of the crystallizer in the falling film manner so as to be gradually cooled and crystallized, gradually growing a uniform crystal layer on a heat exchanging face, and gradually enriching impurities in a mixture solution, wherein the concentration of the uniform crystal layer is higher than that of the mixture solution; regulating the temperature of hot water by utilizing a heat exchanger to carry out partial melting operation, namely a sweating process, on the crystal layer, and partially melting and eliminating low-melting-point impurities included in the crystal layer, so as to further purify crystals. The production process has the advantages that the process is simple, and the structures of devices are compact; by utilizing the falling film manner, the energy is reduced, and meanwhile, the cost and the equipment investment are lowered; the purities of products produced by utilizing the melt crystallizer are high.

Description

Technical field [0001] The present invention involves a purification method of dehydrogenolate, especially a method of littering dehydrogenoic acid by melting crystal device. Background technique [0002] Desertic acid is a broad -spectrum feed preservative that can inhibit the growth of mold, yeast and bacteria.The bacteriostatic effect is basically not affected by pH, but the effect of anticorrosive effect under neutral conditions is the best.It is also used as food preservatives. Domestic regulations can be used for anticorrosion of bean curd, pickles and juice orange sauce. The maximum usage amount is 0.3g / kg. At the same timeSex food preservatives.Since the discovery of antibacteriality in 1940, it has received the attention of many countries, and has been permitted for food anticorrosion.As a food additive, dehydrogenot acid is allowed to be used for cheese, butter, artificial cream, cool beverages, fermented milk and lactic acid bacteria beverages, bean sauce, stuffing, et...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D309/38
CPCC07D309/36
Inventor 许卫东卞杨伟
Owner NANTONG ALCHEMY BIOTECH DEV
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