Method for continuously preparing toluene diisocynate

A technology of toluene diisocyanate and toluene diamine, applied in the field of continuous preparation of toluene diisocyanate, can solve the problems of increasing production cost, increasing TDI production cost, burden of slag removal system, etc.

Active Publication Date: 2010-07-14
甘肃银光聚银化工有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The production of toluene diisocyanate (TDI) generally adopts following two kinds of processes in the world at present: the first kind is to use diethyl isophthalate (DEIP) as solvent, carry out photochemical reaction under high pressure condition, namely The so-called "heavy solvent production process"; but in the photochemical reaction of this process, the solvent diethyl isophthalate (DEIP) easily reacts with phosgene to generate m-ethyl benzoyl chloride (CBC), which The substance is easy to cause blockage of the reactor; in addition, because DEIP is expensive, its large consumption will increase the cost of the final product TDI; moreover, there is another defect in this process, in order to recover the residual phosgene in the system, it is necessary to add A phosgene recovery unit uses toluene as a solvent for phosgene recovery, which adds difficulties to the production control of TDI
The second is to use o-dichlorobenzene (ODCB) as a solvent to carry out photochemical reaction under low pressure conditions, whi...

Method used

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  • Method for continuously preparing toluene diisocynate
  • Method for continuously preparing toluene diisocynate
  • Method for continuously preparing toluene diisocynate

Examples

Experimental program
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Effect test

Embodiment 1

[0040] According to the ratio of phosgene and toluenediamine 4: 1 (molar ratio), use phosgene pump P400 to add -5 ℃ liquid phosgene into the jet reactor C400, and enter the reaction zone of the jet reactor by rotary atomization from the outlet end of the nozzle; 120 The DEIP solution of 21% toluene diamine at °C is input into the injector C400, and the mixed reaction is carried out at the reaction zone of the jet reactor, the reaction temperature is about 100 °C, and the pressure at the feeding port is 2.05MPa. The mixed solution of toluene dicarbamoyl chloride, solvent DEIP and excess phosgene obtained after the reaction in the jet reactor enters the thermal photochemical reaction tower K410 at the fifth tray, and the bottom of the tower is heated. The liquid level of the K410 tower tank is 50%, and the operation The temperature at the top of the tower is 80°C, the pressure is 1.5MPa, the bottom of the tower is 160°C, and the temperature in the middle of the tower is 85°C. To...

Embodiment 2

[0044] The mixed solution of 15% toluenediamine and DEIP at 110°C and the liquid phosgene at -10°C were respectively introduced into the ejector reactor, the molar ratio of the reactants toluenediamine to phosgene was 1:1.5, and the reaction temperature was controlled at 90°C. The operating pressure is 1.5MPa, the reaction solution is transferred from the outlet of the jet reactor C400 to the bottom of the tower reactor K410, the temperature at the bottom of the tower is 148°C, the temperature at the top of the tower is 80°C, and the top product is a mixture of phosgene and hydrogen chloride gas. The temperature in the middle is 95°C, and the pressure inside the tower is 2MPa. More than 90% of high-purity phosgene can be separated and recovered in the tower.

[0045] The process conditions of reactor and tower are controlled in the following table:

[0046]

[0047]

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Abstract

The invention relates to a method for continuously preparing toluene diisocynate, in particular to a method for preparing coarse toluene diisocynate by a phosgene method. The method comprises the following steps: mixing toluene diamine and DEIP solvent, performing low-temperature photochemical reaction on the mixture and excessive liquid phosgene in a jet reactor, heating and cracking a reaction product in a photochemical reaction tower to further decompose toluene dicarbamic chloride serving as an intermediate product to form the toluene diisocynate, recycling the reclaimed phosgene and the DEIP solvent, and delivering the hydrogen chloride gas serving as a side product to a hydrogen chloride absorption system.

Description

technical field [0001] The invention relates to a method for continuously preparing toluene diisocyanate, in particular to a method for preparing crude toluene diisocyanate by a phosgene method. In this method, toluene diamine is mixed with solvent DEIP, and the low-temperature photochemical reaction is carried out with excess liquid phosgene in the jet reactor, and then heated and cracked in the photochemical reaction tower to further decompose the intermediate product toluene dicarbamoyl chloride to generate toluene For diisocyanate, the recovered phosgene and solvent DEIP are recycled, and the by-product hydrogen chloride gas is sent to the hydrogen chloride absorption system. Background technique [0002] Toluene diisocyanate (TDI) is one of the most used isocyanate products in the world and one of the main raw materials of polyurethane. The TDI production process is mainly to generate phosgene (COCL) by the reaction of carbon monoxide provided by gas purification and c...

Claims

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Application Information

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IPC IPC(8): C07C265/14C07C263/04C01B7/01
Inventor 马建军胡安魁罗代晏谭心舜
Owner 甘肃银光聚银化工有限公司
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