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Method for recovering ethyl chloride from exhaust gas containing ethyl chloride in the production of ethyl maltol and its homologues

A technology of ethyl maltol and ethyl chloride, applied in the chemical industry, can solve the problems of low added value and food safety risks, and achieve the effect of low reaction toxicity and low separation difficulty

Active Publication Date: 2022-05-20
河北省天利海香精香料有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

One kilogram of ethyl maltol is produced as a by-product of 2 kilograms of methyl chloride. Due to the limitation of process conditions, the purity of the by-produced methyl chloride is usually only about 98%, and it contains impurities such as methyl ether, water, and methanol, so the added value is not high.
In addition, methyl ethyl maltol is used as a food additive, and methanol is used as a solvent in the production process to carry out the reaction. It is inevitable that trace amounts of the finished product will be carried into the final product of methyl ethyl maltol, bringing potential food safety risks
And using methanol as a solvent, from the perspective of occupational health, there is also a certain practice health risk

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] In the chlorination reaction stage of preparing maltol or ethyl maltol, in the best solvent ratio (ethanol content 60%-77%, moisture 20%-35%, ethyl propionate 2%-7%, hydrochloric acid 0.5% -1.8mol / L, ether 1%-3%), make α-furan alkanol and chlorine carry out chlorination reaction, then carry out chloroethane gas recovery in the heating hydrolysis process, and concrete recovery process is as follows:

[0027] (1) Condensation collection of mixed steam: pump all the materials generated after the chlorination reaction is complete into the hydrolysis kettle, open the displacement vent valve of the hydrolysis kettle, slowly heat the materials in the kettle, remove residual chlorine and air, and when the temperature in the kettle rises to At 5°C, close the displacement vent valve, open the ethanol recovery valve, the gas generated by hydrolysis and heating is condensed by the condenser (water cooling), the condensate enters the collection tank, and the mixed gas containing chlo...

Embodiment 2

[0033] In the production of ethyl maltol and its homologues, the method for recovering chloroethane from chloroethane waste gas comprises the following steps:

[0034] (1) all the materials produced after the chlorination reaction are completely pumped into the hydrolysis kettle, slowly heat the material in the kettle, and when the temperature in the kettle rises to 76 ℃, start to reclaim ethyl chloride;

[0035] (2) the mixed gas of the chloroethane collected in step (1) is condensed, the mixed liquid phase material obtained is pumped into the stripping tower, the temperature of the control tower still is at 65°C, and the tower top temperature is controlled at 35°C, the collection tower Top crude chloroethane gas;

[0036] (3) the crude chloroethane gas obtained in step (2) is passed into the caustic washing tower, and the lye is circulated and sprayed, and the pH of the control lye is 9.0, and the tower top chloroethane gas is condensed by the condenser;

[0037] (4) the co...

Embodiment 3

[0040] In the production of ethyl maltol and its homologues, the method for recovering chloroethane from chloroethane waste gas comprises the following steps:

[0041] (1) all the materials produced after the chlorination reaction is completely pumped into the hydrolysis still, slowly heat the material in the still, when the temperature in the still rises to 78 ℃, start to reclaim ethyl chloride;

[0042] (2) the mixed gas of the chloroethane collected in step (1) is condensed, the mixed liquid phase material obtained is pumped into the stripping tower, the temperature of the control tower still is at 60 ℃, and the temperature at the top of the tower is controlled at 33 ℃, and the collection tower Top crude chloroethane gas;

[0043] (3) the crude chloroethane gas obtained in step (2) is passed into the caustic washing tower, and the lye is circulated and sprayed, and the pH of the control lye is 9.5, and the tower top chloroethane gas is condensed by the condenser;

[0044] ...

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Abstract

The invention discloses a method for recovering chloroethane from chloroethane waste gas in the production of ethyl maltol and its homologues, and belongs to the technical field of chemical industry. In this method, the mixed steam of ethanol and ethyl chloride is first condensed and recovered, and the exhaust gas containing ethane and hydrochloric acid is sprayed with alkali to remove hydrochloric acid, and the crude product of ethyl chloride is obtained through low-temperature condensation; at the same time, the recovered ethanol solution containing ethyl chloride is passed through The stripper is stripped, the alkali is sprayed, and the crude ethyl chloride is obtained by condensation; the crude ethyl chloride obtained in the above two steps is refined through an ethyl chloride rectifying tower to obtain pure ethyl chloride. The present invention uses ethanol instead of methanol as the reaction solvent, the reaction toxicity is low, the separation difficulty of the generated ethanol and ethyl chloride mixed steam is relatively low, and the recovered ethyl chloride is safer, and the recovered ethyl chloride can be used as the production of ethyl malt The raw material for the upstream reaction of phenols is used.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, and particularly relates to a method for recovering chloroethane from chloroethane-containing waste gas in the production of ethyl maltol and its homologues. Background technique [0002] At present, furfural obtained by hydrolysis of corn cob is used as raw material in China, and then α-furan alkanol is obtained through Grignard reaction. The obtained α-furan alkanol uses methanol as a solvent, and α-furan alkanol and chlorine are subjected to chlorination-hydrolysis reaction , to obtain methyl maltol and ethyl maltol series products. In the chlorination-hydrolysis reaction process, the side reaction of producing methyl chloride will occur. The methyl chloride produced has a relatively low boiling point and is mixed with methanol, methyl ether, HCl and other substances, and it is difficult to separate, purify and recover. In the production process, the vented waste gas containing meth...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C17/38C07C17/395C07C17/383C07C19/043
CPCC07C17/38C07C17/395C07C17/383C07C19/043Y02P20/10
Inventor 李金合官伟王军于福新李杭张晓峰宁洪良
Owner 河北省天利海香精香料有限公司
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