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Method for manufacturing isocyanates in the gaseous phase

一种异氰酸酯、气相的技术，应用在在气相中制备异氰酸酯领域，能够解决缩短光气化装置可利用时间、反应器堵塞、混合器堵塞等问题

Active Publication Date: 2008-06-25
COVESTRO DEUTSCHLAND AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage of using such a micromixer is that even very small amounts of solids, the formation of which cannot be completely excluded in the isocyanate synthesis, can lead to clogging of the mixer and thus shorten the availability of the phosgenation plant
However, if better heat exchange with the reactor wall is to be achieved, WO 03 / 045900 teaches that the reaction should be carried out in a reaction chamber with a small height (for example only a few centimeters or millimeters), thus having such a reactor size, As pointed out in WO 03 / 045900 commenting on EP-928 758: even the smallest amount of solids, whose formation cannot be completely avoided in the synthesis of isocyanates, may lead to clogging of the reactor, thereby reducing the time available for the phosgenation unit

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] Example 1 "Diadiabatic phosgenation of TDA" (comparative example)

[0041] At 400° C., 20 kg / h of a mixture of 2,4- and 2,6-toluenediamine in a weight ratio of 80%:20% was vaporized and introduced in gaseous form into the tubular reactor. Simultaneously in parallel operation, 100 kg / h of gaseous phosgene were heated to 310° C. and likewise introduced into the tubular reactor. The streams are injected through nozzles into the mixing zone and mixed before entering the reaction chamber. The mixing zone is thermally insulated to prevent heat loss before and during mixing. The reaction chamber is not thermally insulated and is cooled by thermal radiation. The reaction conditions are therefore non-adiabatic. The gaseous mixture leaving the tubular reactor after 2.2 seconds had a final temperature of 380° C. and was cooled by injection of o-dichlorobenzene. The isocyanate formed is condensed, washed and then worked up by distillation by known methods. The pressure diffe...

Embodiment 2

[0042] Example 2 "Adiabatic phosgenation of TDA" (invention)

[0043] At 320 °C, 20.5 kg / h of a mixture of 2,4- and 2,6-toluenediamine in a weight ratio of 80%:20% is vaporized and introduced into the tubular reactor in gaseous form together with 500 kg / h of nitrogen . Simultaneously in parallel operation, 182 kmol / h of gaseous phosgene and 1000 kg / h of o-dichlorobenzene were heated to 360° C. and likewise introduced into the tubular reactor. The streams are injected through nozzles into the mixing zone and mixed before entering the reaction chamber. The mixing zone and reaction chamber are thermally insulated so that there is no additional heat input due to heating and no heat dissipation due to external cooling or thermal radiation. The reaction is thus carried out under adiabatic conditions. At the outlet of the reaction chamber, the final temperature measured using a surface thermometer was 405°C. The gaseous mixture leaving the reaction chamber after 5.5 seconds is ...

Embodiment 3

[0044] Example 3 "Adiabatic phosgenation of IPDA" (invention)

[0045] 17.6 kmol / h of isophoronediamine were vaporized together with 42 kg / h of nitrogen, superheated to a temperature of 300° C. and introduced in gaseous form into the tubular reactor. At the same time in parallel operation, 64 kmol / h of gaseous phosgene was heated to 300° C. and likewise introduced into the tubular reactor. The streams were mixed and entered the reaction chamber with a mixing time of 0.02 seconds. Thermally insulate the mixing zone and reaction chamber so that there is no additional heat input due to heating and no heat dissipation due to external cooling or thermal radiation. The reaction is thus carried out under adiabatic conditions. At the outlet of the reaction chamber, the final temperature measured using a surface thermometer was 450°C. The gaseous mixture leaving the reaction chamber after 0.1 s is cooled by injection of monochlorobenzene, and the isocyanate formed is condensed, wa...

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PUM

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Abstract

An isocyanate is produced by reacting a primary amine with phosgene in the gas phase above the boiling point of the amine over an average contact time of 0.05 to 15 seconds under adiabatic conditions.

Description

technical field [0001] The present invention relates to a process for the preparation of isocyanates by reacting primary amines with phosgene under adiabatic conditions at the boiling point of said amines with an average contact time of 0.05-15 seconds. Background technique [0002] Various processes are known from the prior art for preparing isocyanates in the gas phase by reacting amines with phosgene. EP-A 593 334 describes a process for the preparation of aromatic diisocyanates in the gas phase, in which the reaction of diamines with phosgene is carried out in a tubular reactor which has no dynamic The longitudinal axis of the tubular reactor narrows. However, this method is problematic because the educt stream does not function as well as it does with appropriate mixing elements simply by narrowing the walls of the tube to mix. Poor mixing often results in the formation of large amounts of undesired solids. [0003] EP-A-699 657 describes a process for the preparatio...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C263/10C07C265/14
CPCC07C263/10C07C2101/14C07C2601/14C07C265/14C07C263/18
Inventor F·波尔K·比斯库普R·布鲁恩斯F·斯特芬斯H·斯图茨
Owner COVESTRO DEUTSCHLAND AG
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