Method for the preparation of isocyanate by partially adiabatic phosgenation of the corresponding amine

A technology of isocyanate and phosgene, applied in chemical instruments and methods, preparation of isocyanic acid derivatives, preparation of organic compounds, etc., can solve problems such as not publicly regulating temperature

Pending Publication Date: 2020-05-19
COVESTRO DEUTSCHLAND AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Regulating the temperature in an adiabatically operated reactor by means of a targeted closed-loop control of the reactant temperature is not disclosed in EP 1 616 857 A1

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1 to 4

[0094] The temperature of the amine solution and the phosgene solution was varied to examine the effect on the quality (color value, NCO index and acidity) of the obtained product. The operating conditions can be found in Table 1.

[0095] It can be seen that the color value, NCO index and acidity value are generally best when the outlet temperature of the amine solution and the phosgene solution (which determines the mixer outlet temperature under given boundary conditions) is low (Example 4). This shows the great importance of the method according to the invention, which enables rapid inverse control and thus regulation of the temperature in the reactor of step IV) in a simple manner in the event of undesired deviations in the mixer outlet temperature.

[0096] Table 1: Operating conditions and results in Examples 1 to 4

[0097] Example T(MDA solution) / ℃ T(COCl 2 ) solution / ℃

T(Mixer outlet) / ℃ Yellow value E430 Gray value E520 NCO value / % A...

Embodiment 5

[0102] Embodiment 5 (the present invention): the method of the present invention is used for the computer simulation of industrial scale production

[0103] In the MDI plant, 40.0 t / h of MDA at a temperature of 130°C was mixed with 94.5 t / h of MCB at a temperature of 52°C as solvent by means of a static mixer to produce a 30.0% MDA solution (step 1) ). Phosgene was mixed with MCB in a phosgene dissolution tank to obtain a 60.0% phosgene solution (step II)). Each hour, 106.7 tons of this phosgene solution at a temperature of 3.0°C passed through the heat exchanger and were thereby cooled to a temperature of -1°C. In a similar manner, 134.5 tons per hour of a 30% MDA solution at a temperature of 80.0°C passed through a heat exchanger and thereby cooled to a temperature of 60°C. The MDA solution and the phosgene solution thus tempered enter the dynamic mixer (step III)). The temperature at the outlet of the dynamic mixer was adjusted to 130°C.

[0104] The liquid reaction m...

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PUM

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Abstract

The present invention relates to a process for preparing an isocyanate by reacting a primary amine with phosgene, comprising I) providing an amine solution and adjusting its temperature in a heat exchanger, II) providing a phosgene solution and adjusting its temperature in a heat exchanger, III) mixing the amine solution with the phosgene solution in a mixing unit, followed by IV) further conversion in an adiabatically operated reaction zone and the removing of the gas phase formed as a result of the chemical reaction in a separation zone, V) expanding the remaining liquid phase, VI) further conversion of the liquid phase remaining after expansion in an indirectly heated reaction zone and VII) isolating the isocyanate from the reaction solution obtained therein, in which the temperature inthe reaction zone and separation zone is adjusted by fixing a target value within a range from 110 DEG C to 145 DEG C. for the temperature of the reaction mixture from step III) and using the actualtemperature of the reaction mixture from step III) measured continuously or at intervals for closed-loop control of the temperature of the solution of the primary amine provided in step I) and / or of the temperature of the solution of phosgene provided in step II) by means of the heat exchangers used to adjust the temperature of each of these solutions.

Description

technical field [0001] The present invention relates to a process for the preparation of isocyanates by reacting primary amines with phosgene comprising I) providing an amine solution and tempering it in a heat exchanger, II) providing a phosgene solution and tempering it in a heat exchanger , III) mixing of the amine solution with the phosgene solution in the mixing unit, followed by IV) further reaction in the adiabatically operated reaction zone and separation of the gaseous phase formed as a result of the chemical reaction in the separation zone, V) depressurization of the remaining liquid phase , VI) further reacting the liquid phase remaining after decompression in an indirectly heated reaction zone and VII) separating the isocyanate from the reaction solution obtained here, wherein the temperature in the reaction zone and the separation zone is adjusted as follows: The temperature of the reaction mixture of step III) specifies a target value in the range of 110° C. to 1...

Claims

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Application Information

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IPC IPC(8): C07C263/10C07C265/14
CPCC07C263/10C07C265/14B01J19/0013B01J19/0066B01J19/1812B01J2219/00051C07C263/20
Inventor T.克瑙夫C.斯蒂芬斯A.希尔舍尔D.瓦斯蒂安J.施普里瓦尔德
Owner COVESTRO DEUTSCHLAND AG
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