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Improving method for preparing (poly) isocyanate by gas phase

A technology of isocyanate and phosgene, applied in the field of isocyanate production, can solve problems such as undesired parallel or subsequent reactions, increased thermal decomposition of products, and uneven temperature distribution

Inactive Publication Date: 2003-06-25
COVESTRO DEUTSCHLAND AG
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  • Summary
  • Abstract
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  • Claims
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Problems solved by technology

[0005] Inadequate mixing or backmixing can result in a proportion of educts and prolonged residence time of the product, leading to undesired parallel or subsequent reactions
In some cases, another consequence of insufficient mixing is uneven temperature distribution in the reactor
As a result, overheating of certain zones in the reactor may occur, resulting in increased thermal decomposition of the product

Method used

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  • Improving method for preparing (poly) isocyanate by gas phase

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example 1

[0044] Isophoronediamine (IPDA), phosgene and nitrogen in a molar ratio of 1:4:0.1 are continuously flowed into the stage with downstream diisocyanate condensation (and subsequent isocyanate processing) in the mixing tube. The educts were evaporated separately from each other in an upstream heat exchanger and adjusted to a temperature of 320°C. A mixture of nitrogen and IPDA (E1) flows through the nozzle, while phosgene (E2) flows through the annular space around the nozzle. The diameter ratio between nozzle (d) and reaction chamber (D) is 0.18:1. The pressure in the reaction zone is slightly above atmospheric pressure. The flow velocity of the reaction mixture downstream of the nozzle is about 20 m / s. After leaving the reactor, the reaction product isophorone diisocyanate (IPDI) is condensed and separated from excess phosgene and secondary products, hydrogen chloride, and sent for purification. The yield of IPDI relative to the incorporated IPDA was 98.8% of theory. This...

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Abstract

The present invention relates to a process for the production of an isocyanate corresponding to the formula R(NCO)n wherein R and n are defined in the description, by a) separately heating an amine corresponding to the formula R(NH2)n, in vapor form, optionally diluted with an inert gas or the vapors of an inert solvent, and phosgene to temperatures of 200 DEG C. to 600 DEG C., b) continuously reacting the optionally diluted amine and phosgene in a reactor which has a reaction chamber that does not have moving parts, wherein the reactor has a diameter D and centrally located in the reactor is a nozzle having an orifice diameter d, i) by introducing phosgene through the annular space around the nozzle such that the amine and phosgene flow in parallel through the reactor, wherein the gas velocity of the optionally diluted amine is higher than the gas velocity of phosgene and the ratio of the diameter d to the reactor diameter D is from 5% to 45%.

Description

technical field [0001] The present invention relates to an improved process for the production of (poly)isocyanates in the gas phase by optimizing the mixing of reactants. Background technique [0002] It is known that good mixing of reactants plays an important role in improving the conversion and selectivity of gas phase reactions. Examples are the gas-phase phosgenation of aromatic or (cyclo)aliphatic polyfunctional amines. In continuous processes, educts are traditionally introduced into the reactor in gaseous form, as described in numerous patent applications (e.g. E-A-676 392, EP-A 570 799, EP-A 289 840, EP-A 749958 ) as described. Mixing between the reaction partners should take place within a maximum of 0.5 seconds to 10 -3 degree of segregation. The degree of resolution is a measure of incomplete mixing (EP-A 570 799). [0003] Methods for achieving short mixing times are known in principle. Mixing devices with dynamic or static mixing elements are suitable. ...

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 M·弗里德里希H·施图茨
Owner COVESTRO DEUTSCHLAND AG
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