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Method for preparing isocyanate by salifying-atomizing phosgenation method

A technology of isocyanate and phosgenation, which is applied in the preparation of amino compounds, chemical instruments and methods, and the preparation of isocyanic acid derivatives. It can solve the problems of high amine stability requirements, increased polymer content, and low production efficiency. The effect of reducing stability requirements, increasing product yield, and saving production costs

Active Publication Date: 2020-10-27
WANHUA CHEM GRP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Both the gas-phase method and the liquid-phase method have certain defects: the gas-phase method needs to vaporize the amine at high temperature first, and the reaction speed with phosgene is fast, so it is not suitable for heat-sensitive amines, and it is easy to cause amine coating. Produce urea by-products; the liquid phase method has a high viscosity due to the formation of hydrochloride in the first step, and the dispersion effect is poor in the photochemical reaction process, requiring a long photochemical reaction time, thereby limiting the reaction concentration and Increased polymer content
[0003] Chinese published patent CN200680022170.3 reports that the salt formation process is carried out at a pressure of 0.01Mpa above atmospheric pressure and a temperature of 120°C. Although high temperature and pressure can reduce the viscosity of hydrochloride and improve the conversion rate of salt formation and space-time efficiency, there are two aspects Disadvantages: On the one hand, it is only suitable for diamines with high stability at high temperatures, and it will lead to an increase in chlorinated impurities; package problem
Although this method can obtain hydrochloride with better dispersibility, the pores on the rotating disc are easily blocked, which may not achieve the desired effect, and the energy consumption of the overall equipment is relatively high
[0006] Patents US7019164B2, EP1935876A1, CN201710861344.5, etc. all use gas-phase photochemical method to prepare isocyanate. During the gasification process of amine, there will be a problem of incomplete gasification with pressure loss, and the formation of amine droplets will not react in the photochemical reactor. By-products are completely formed, causing problems such as clogging or coking of reaction tubes
[0007] At present, the liquid-phase phosgenation method generally has the problems of low reaction concentration, long reaction time, and low production efficiency; although the gas-phase method can increase the reaction rate, it has high requirements for the thermal stability of the amine, and high-temperature coking or The problem of increased by-products
Therefore, it is necessary to develop a new method for preparing isocyanate to solve the problems of slow reaction rate, high requirement for amine stability, and many reaction impurities.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0050] Preparation of hydrochloride: Put 1200kg of m-xylylenediamine and 4800kg of chlorobenzene into the salt-forming reactor to form a mixed solution, and stir evenly. Then, the temperature in the reactor was controlled at 7°C, the reaction pressure was 0.09MPa, and the hydrogen chloride gas was blown into the tube at 200Nm 3 The speed of / h starts to feed hydrogen chloride gas into the reactor, and stops feeding hydrogen chloride after 3 hours to obtain a diamine hydrochloride solution. The obtained hydrochloride solution is filtered and dried in a three-in-one machine to obtain m-Xylylenediamine hydrochloride solid.

[0051] Preparation of isocyanate: Preheat phosgene, nitrogen and m-xylylenediamine hydrochloride to 350°C respectively, first pass phosgene into the photochemical reactor at a flow rate of 425kg / h, and after 30min, start to pass through the circular slot type The atomizing nozzle will 0.5Mpa pressure, 100Nm 3 The nitrogen gas of / h flow is passed into the r...

Embodiment 2

[0055] Preparation of hydrochloride: Put 880kg of 1,4-butanediamine and 4990kg of toluene into the salt-forming reactor to form a mixed solution, and stir evenly. Then, the temperature in the reactor was controlled at 15°C, the reaction pressure was 0.12MPa, and the hydrogen chloride gas was blown into the tube at 370Nm 3 The speed of / h starts to feed hydrogen chloride gas into the reactor, and stops feeding hydrogen chloride after 3 hours to obtain diamine hydrochloride solution, and the obtained hydrochloride is filtered and dried in a three-in-one machine to obtain 1 , 4-butanediamine hydrochloride solid.

[0056] Preparation of isocyanate: Preheat phosgene, carbon dioxide and 1,4-butanediamine hydrochloride to 300°C respectively, first pass phosgene into the photochemical reactor at a flow rate of 604kg / h, and after 30min, start to pass through the ring The slit atomizing nozzle will have a pressure of 0.8Mpa and a flow rate of 200Nm 3 / h of carbon dioxide (the content ...

Embodiment 3

[0060] Preparation of hydrochloride: Put 2000kg of aniline and 2000kg of o-dichlorobenzene into the salt-forming reactor to form a mixed solution, and stir evenly. Then, the temperature in the reactor was controlled at 50°C, the reaction pressure was 0.3MPa, and the hydrogen chloride gas was blown into the tube at 640Nm 3 The speed of / h starts to feed hydrogen chloride gas into the reactor, and stops feeding hydrogen chloride after 3 hours to obtain aniline hydrochloride solution without desolvation treatment.

[0061] Preparation of isocyanate: Preheat phosgene, argon and aniline hydrochloride solution to 250°C respectively, first pass phosgene into the photochemical reactor at a flow rate of 794kg / h, and after 30min, start to atomize through annular gap The nozzle will have a pressure of 1.5Mpa and a flow rate of 300Nm 3 / h of argon (in which the content of copper powder is 80g / Nm 3 ) into the photochemical reactor, the final flow velocity in the reactor and the amine hyd...

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Abstract

The invention relates to a method for preparing isocyanate by a salifying-atomizing phosgenation method. The method comprises the following steps: mixing amine and hydrogen chloride to prepare amine hydrochloride, atomizing the hydrochloride stream in a photochemical reactor by a high-speed inert gas stream sprayed by an atomizing nozzle, reacting with phosgene to prepar isocyanate, and cooling the isocyanate leaving the reactor in a swabbing tower. According to the method, the loss caused by direct high-temperature gasification of the amine in a traditional gas phase method is avoided, and the problem of low reaction efficiency of the hydrochloride and the phosgene in a traditional liquid phase method is solved.

Description

technical field [0001] The invention relates to a method for preparing isocyanate, in particular to a method for preparing isocyanate by a salt-forming-atomization phosgenation method. Background technique [0002] In the prior art, the process of preparing isocyanates by reacting organic primary amines with phosgene in an inert solvent is well known. The phosgene method is mainly divided into gas-phase method and liquid-phase method. The gas-phase method is to directly react primary amine with phosgene to prepare isocyanate. The liquid phase method is divided into liquid phase salt formation and liquid phase cold and heat method. The liquid phase salt formation method is to first react the corresponding amine with acid gas such as hydrogen chloride, carbon dioxide, etc. to prepare amine hydrochloride or carbonate, and then The amine salt reacts with phosgene to prepare isocyanate; the liquid-phase thermothermal method firstly reacts amine and phosgene at low temperature to...

Claims

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Application Information

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IPC IPC(8): C07C263/10C07C265/14
CPCC07C263/10C07C209/00C07C265/14C07C211/46C07C211/09C07C211/51
Inventor 陈浩尚永华李建峰朱付林史培猛吴谦石滨黎源
Owner WANHUA CHEM GRP