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Purification method of p-dichlorobenzene

A technology of p-dichlorobenzene and purification method, applied in chemical instruments and methods, halogenated hydrocarbon preparation, solution crystallization, etc., can solve the problems of difficult industrial amplification, unstable product quality, low product purity, etc. Conducive to the effect of large-scale and simple equipment structure

Inactive Publication Date: 2014-05-07
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The technical problem to be solved by the present invention is that in the prior art, the product quality of p-dichlorobenzene purification process is unstable, the product purity is low, and it is not easy for industrial scale-up. A new purification method for p-dichlorobenzene is provided. The method has the advantages of high purity of the produced p-dichlorobenzene product and easy industrial scale-up of equipment

Method used

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  • Purification method of p-dichlorobenzene
  • Purification method of p-dichlorobenzene
  • Purification method of p-dichlorobenzene

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0033] The crystallizer 1 for the purification of p-dichlorobenzene, the crystallizer shell 2 is closed at the opposite end by the top plate 3 and the lower head 15, the falling film crystallizing tube 5 is provided in the crystallizer shell 2 and the upper part of the crystallizer 1 Material inlet 6 and material overflow port 7; the lower head 15 of the crystallizer is provided with a material outlet 14; the falling film crystallization tube is provided with a distributor 4; the upper part of the crystallizer shell is provided with a cooling medium inlet 17, and the lower part is provided with a cooling medium outlet 13. A cooling medium distribution tray 10 is provided in the crystallizer. The cooling medium distribution tray 10 is provided with a cooling medium guide hole 16, an overflow weir 11, and a downcomer 12; the falling film crystallization tube 5 passes through the guide hole 16. Fix by the upper tube plate 8 and the lower tube plate 9.

[0034] The mold shell 2 is cy...

Embodiment 2

[0042] The crystallizer of Example 1 is used for mixing dichlorobenzene to purify high-purity p-dichlorobenzene 99.7%.

[0043] The mass concentration of p-dichlorobenzene in the mixed dichlorobenzene feed is 65%, and the rest is m-dichlorobenzene, o-dichlorobenzene, trichlorobenzene, etc.

[0044] The purification operation of p-dichlorobenzene includes three steps of crystallization, evaporation and crystal melting:

[0045] Crystallization: Mix dichlorobenzene at 60°C, feed rate of 500L / h, cooling medium temperature of 30°C, and other operations are the same as in Example 1.

[0046] Evaporation After 2 hours of feeding, stop feeding, and make the cooling medium rise to 53°C at a heating rate of 5°C / h

[0047] Melting the crystals After the evaporation operation is completed, the temperature of the cooling medium is increased to 60°C to melt the crystals to obtain high-purity products, which are discharged from the material outlet 14 for collection. The final product with a mass con...

Embodiment 3

[0050] The crystallizer of Example 1 is used for mixing dichlorobenzene to purify high-purity p-dichlorobenzene 99.5%.

[0051] The mass concentration of p-dichlorobenzene in the mixed dichlorobenzene feed is 40%, and the rest is m-dichlorobenzene, o-dichlorobenzene, trichlorobenzene, etc.

[0052] The purification operation of p-dichlorobenzene includes three steps of crystallization, evaporation and crystal melting:

[0053] Crystallization: Mix dichlorobenzene at 60°C, feed rate 500L / h, cooling medium temperature 5°C, and other operations are the same as in Example 1.

[0054] Evaporation After feeding for 2 hours, stop feeding and make the cooling medium rise to 52.5°C at a temperature rise rate of 10°C / h

[0055] Melting the crystals After the evaporation operation is completed, the temperature of the cooling medium is increased to 60°C to melt the crystals to obtain high-purity products, which are discharged from the material outlet 14 for collection. The final product with a mas...

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Abstract

The invention discloses a purification method of p-dichlorobenzene, which mainly solves the problems of unstable product purity and difficult industrial amplification of a p-dichlorobenzene purification technology in the prior art. The purification method of p-dichlorobenzene adopts the technical scheme that mixed dichlorobenzene enters the top of a crystallizer through a material inlet, a part of mixed dichlorobenzene enters a crystallization pipe through a distributor at the top of the crystallizer, the other part of mixed dichlorobenzene flows out from a material overflow port, a cooling medium enters the crystallizer and forms a cooling medium liquid film on an external wall of a falling film crystallization pipe through cooling medium guide holes in a cooling medium distribution tray, an overflow weir and a downcomer are arranged on the cooling medium distribution tray, the redundant cooling medium flows down to a tray of a next stage through the downcomer and is finally discharged from a cooling medium outlet, the mixed dichlorobenzene liquid film precipitates p-dichlorobenzene crystals on the wall of the crystallization pipe with the fall of temperature, and uncrystallized residual liquid is discharged from a material outlet at the bottom of a tower, so that the problems are better solved, and the method can be used for industrial production of p-dichlorobenzene.

Description

Technical field [0001] The invention relates to a purification method of p-dichlorobenzene. Background technique [0002] P-Dichlorobenzene is a kind of organic synthetic raw material, which can be used to synthesize dyes and pesticide intermediates. At present, p-dichlorobenzene is mainly purified from chlorobenzene in China. The boiling points of various isomers in chlorobenzene are similar, which is difficult High-purity p-dichlorobenzene is purified by conventional distillation. The melting points of the isomers in dichlorobenzene are quite different, and eutectic crystals are formed. It is easier to separate high-purity p-dichlorobenzene by crystallization. chlorobenzene. [0003] The methods and processes for purifying p-dichlorobenzene currently published in China are described in documents such as CN87104975, CN99119873, CN200910135696, CN200910135699, etc. The characteristics of the above-mentioned process for purifying p-dichlorobenzene are: the crystals are obtained by ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C25/08C07C17/392B01D9/02
Inventor 卢咏琰肖剑蔡立鑫郭艳姿
Owner CHINA PETROLEUM & CHEM CORP
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