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Method for preparing isocyanate

A technology of isocyanate and crude isocyanate, which is applied in the preparation of isocyanic acid derivatives, chemical instruments and methods, and the preparation of organic compounds, etc., can solve the problems that the system cannot run stably for a long period of time, so as to prolong the stable operation period of the device and reduce the cost of the device. The number of inspections and the effect of prolonging the service life of equipment

Active Publication Date: 2022-03-08
WANHUA CHEM GRP CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although the above method has improved the equipment corrosion and product quality problems to a certain extent, it has not proposed a solution to the existing problem that the system cannot run stably for a long period of time.

Method used

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  • Method for preparing isocyanate

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0063] The present embodiment provides a kind of method for preparing isocyanate, described method comprises the following steps:

[0064] 1,6-Hexanediisocyanate was prepared by gas-phase phosgenation from 1,6-Hexanediamine and phosgene.

[0065] The molar ratio of phosgene and 1,6-hexamethylenediamine is 7:1, both are preheated to 340°C before entering the reaction zone, the absolute pressure of the reaction zone is 0.12MPa, the temperature is 440°C, and the reaction residence time is 1.8s. After the reaction product leaves the reaction zone, chlorobenzene is used for spraying and trapping. Through rectification (reflux ratio is 4:1), the mass fraction of substances with nitrile structure in spraying chlorobenzene is controlled to be 720ppm, and the pump outlet pressure is 0.4 Mpa (design pressure 0.7Mpa), spray chlorobenzene temperature at 80°C to obtain a liquid stream containing 1,6-hexamethylene diisocyanate, and obtain 1,6-hexamethylene diisocyanate without phosgene and ...

Embodiment 2

[0070] This embodiment provides a kind of method for preparing isocyanate, described method is with reference to the method in embodiment 1, and difference is only: through rectification mode (reflux ratio is 3:1), has nitrile group structure in the control spray chlorobenzene The mass fraction of the substance is 1845ppm.

[0071] Wherein, the substances having a nitrile structure in this embodiment include chloroacetonitrile, chloropropionitrile, valeronitrile, and chlorovaleronitrile. After 4 months of continuous operation, the outlet pressure of the spray liquid pump rose to 0.48Mpa. After shutdown and maintenance, it was confirmed that there was a small amount of solid matter in the outlet pipeline of the spray chlorobenzene pump, and no corrosion points were found in the pipeline, which would not affect the continuous operation of the device.

Embodiment 3

[0073] This embodiment provides a kind of method for preparing isocyanate, described method is with reference to the method in embodiment 1, and difference is only: through rectification mode (reflux ratio is 9:1), the nitrile group structure in the control spraying chlorobenzene The mass fraction of the substance is 25ppm.

[0074] Wherein, the substances having nitrile structure in this embodiment include valeronitrile and chlorvaleronitrile.

[0075] After 3.5 months of continuous operation, the outlet pressure of the spray liquid pump rose to 0.51Mpa. It was confirmed by shutdown and maintenance that there was a small amount of solid matter in the outlet pipeline of the spray chlorobenzene pump, and no corrosion points were found in the pipeline, which would not affect the continuous operation of the device.

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PUM

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Abstract

The invention provides a method for preparing isocyanate, which comprises the following steps of: reacting primary amine with phosgene in a gas phase, capturing a reaction product by using quenching liquid containing an inert solvent, and purifying and separating to obtain the inert solvent and a cyanate product, the inert solvent comprises a substance with a nitrile group structure, and the proportion of the substance with the nitrile group structure is controlled to be 20-2000 ppm based on the mass of the inert solvent in the quenching liquid containing the inert solvent. The method provided by the invention can effectively improve the blockage and corrosion conditions in a solvent system, especially reaction gas phase trapping equipment and pipelines, obtain a longer stable operation period, reduce the maintenance frequency of phosgene-related devices, and improve the safe operation level of the system.

Description

technical field [0001] The invention belongs to the technical field of organic materials, and in particular relates to a method for preparing isocyanate. Background technique [0002] At present, the method of preparing isocyanate by reacting the corresponding amine with phosgene has long been known. In this method, after the corresponding amine and phosgene are heated and vaporized, the contact reaction is carried out at a high temperature of 200-600 ° C to obtain the gas phase isocyanate product. Solvent or solvent-containing isocyanate reaction solution is sprayed and captured to obtain a reaction solution rich in target isocyanate, and then the crude product is obtained after removing phosgene and solvent. The solvent used in this process can be recycled after being separated and purified. However, the current preparation methods are prone to blockage of equipment and abnormal operation. Therefore, it is of great significance to optimize the method of preparing isocyana...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C263/10C07C265/14
CPCC07C263/10C07C265/14
Inventor 韩金平何伟尚永华俞勇王京旭吕振高李文滨曹娜苏黎明黎源
Owner WANHUA CHEM GRP CO LTD
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