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Method for recycling phosgene in tail gas produced through thermo-optical reaction for synthesis of 3,5-dichlorophenyl isocyanate

A technology of dichlorophenylisocyanate and phosgene, which is applied in the preparation of isocyanic acid derivatives, chemical instruments and methods, and the preparation of organic compounds. It can solve the problems of difficult leakage, affecting product quality and yield, and potential accidents problem, to achieve the effect of reducing the risk of leakage

Inactive Publication Date: 2016-10-12
XINYI AGRI CHEM PLANT JIANGSU PROV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] 1. Before recycling, the phosgene toluene liquid needs to be transported over a long distance, and there is a risk of leakage in the back and forth transport. Similar situations have occurred in production
[0004] 2. Before recycling, the water in the exhaust pipe will be cooled down. When returning to the cold light, the solvent will entrain water, which will affect the quality and yield of the product. It is estimated that 20kg of ester will be destroyed per kettle
[0005] 3. There is a large amount of solvent circulation, about 8000L*3 kettles, forming a hidden danger of accidents
[0006] 4. During the operation, it is not conducive to patrol inspection, there is a large amount of liquid light on site, and the leakage is not easy to deal with

Method used

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  • Method for recycling phosgene in tail gas produced through thermo-optical reaction for synthesis of 3,5-dichlorophenyl isocyanate
  • Method for recycling phosgene in tail gas produced through thermo-optical reaction for synthesis of 3,5-dichlorophenyl isocyanate

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Embodiment 1

[0023] Such as figure 1 Shown, a kind of synthetic 3,5-dichlorophenyl isocyanate thermo-optic reaction tail gas recycles the method for phosgene in tail gas, carries out as follows:

[0024] Step 1) Put the phosgene-toluene solution in the tail gas cooling pot 2 into the cold light kettle 3, then add the 3,5-dichloroaniline toluene solution in the dropping tank 1 into the cold light kettle 3 dropwise, and stir At the same time, store phosgene I from the bottom of the luminescent kettle 3 and stir evenly to obtain a mixed solution; the temperature of the tail gas cooling pot 2 is controlled at -5~0°C; the temperature of the luminescent kettle 3 is controlled at 0~5°C;

[0025] In the described phosgene-toluene solution, its phosgene consumption is 200m³, and the toluene consumption is 3500L;

[0026] The amount of 3,5-dichloroaniline is 800kg, and the amount of phosgene I is 120m³;

[0027] Step 2) Transfer the mixed liquid to the thermo-optical kettle 4, and stir to raise th...

Embodiment 2

[0032] Synthesis: Dissolve 800kg of 3,5-dichloroaniline in 1850L of toluene, then add 3500L of toluene to the cold light kettle 3, store luminescence of 200 m³, then add the aniline toluene liquid dropwise and let the light pass through 120m³, and discharge the material into the thermolight kettle 4. Through heat and light 120m³, phosgene has a total mass of 440m³ and a mass of 1496kg.

[0033] 1. Put the phosgene toluene liquid absorbed in the tail gas cooling pot into the cold light kettle, add 3,5-dichloroaniline and toluene mixture dropwise under stirring, store the cold light and drop the light passing time according to the liquid level of the tail cold pot - Lighting schedule, see Table 1; transfer materials from cold light kettle 3 to hot light kettle 4.

[0034] 2. After the cold light kettle 3 is fed into the hot light kettle 4. Open the gas valve on the thermo-optic kettle 4, the return valve, and confirm that the brine valve of the thermo-optic condenser 5 is close...

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Abstract

The invention discloses a method for recycling phosgene in tail gas produced through a thermo-optical reaction for synthesis of 3,5-dichlorophenyl isocyanate. The method comprises steps as follows: a phosgene-toluene solution in a tail gas cooling pan is fed into a cold-light kettle, a 3,5-dichloroaniline toluene liquid in a dropping addition tank is dropwise added to the cold-light kettle, and phosgene I is introduced from the bottom of the cold-light kettle; a mixed solution is transferred into a thermo-optical kettle, and phosgene II is introduced from the bottom of the thermo-optical kettle until the toluene solution is transparent; gas produced in a reaction process enters a thermo-optical condenser, non-condensing gas is introduced into a thermo-optical tail gas buffer kettle and is heated to 80 DEG C, and the heated gas is introduced into the tail gas cooling pan; a condensed liquid in the thermo-optical condenser and a liquid in the thermo-optical tail gas buffer kettle are subjected to acid distribution treatment, a product is introduced into the thermo-optical kettle through a pipe, and reflux is formed; N2 is introduced from the bottom of the thermo-optical kettle in a reflux process for light repelling; a material is flirted by a filter device, then is introduced into an intermediate tank and is introduced into a next procedure through a pump P1.

Description

technical field [0001] The invention relates to a method for recovering and recycling phosgene in the tail gas of thermo-light reaction for synthesizing 3,5-dichlorophenyl isocyanate. Background technique [0002] Prior art has following shortcoming: [0003] 1. Before recycling, the phosgene toluene liquid needs to be transported over a long distance, and there is a risk of leakage in the back and forth transport. Similar situations have occurred in production. [0004] 2. The water in the tail gas pipe will be cooled down during recycling before, and the solvent will entrain water when returning to the cold light, which will affect the quality and yield of the product. It is estimated that 20kg of ester will be destroyed per kettle. [0005] 3. There is a large amount of solvent circulation, about 8000L*3 kettles, forming a hidden danger of accidents. [0006] 4. During the operation, it is not conducive to patrol inspection, there is a large amount of liquid light on si...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C263/10C07C265/12
CPCC07C263/10C07C265/12
Inventor 刘宇纪传武魏星蔡小飞解恒参于殿宝
Owner XINYI AGRI CHEM PLANT JIANGSU PROV
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