Covestro Deutschland Ag

Juergen Spriewald

Thomas Knauf

Dietmar Wastian

Anke Hielscher

Christian Steffens

Volker Michele

Dirk Manzel

Peter Plathen

Achim Wildermuth

The present invention relates to a method for operating a plant for continuous production of an isocyanate by converting a primary amine A with phosgene P whilst maintaining, based on the amino groups of the primary amine, a stoichiometric excess of phosgene in the presence of a solvent L in the liquid phase, using a first, adiabatically operated reaction chamber and a second, isothermally operated reaction chamber. The method is characterised in that a combination of measures, in particular the maintenance of a sufficiently high starting pressure and a sufficiently high starting temperature, is applied in order to bring the plant back into the target state, standard operation, starting from a state of interruption to production.

Method for operating a plant for continuous production of an isocyanate

The invention relates to a method for operating a production plant for producing a chemical product () by reacting a H-functional reactant () with phosgene () during an interruption in production when taking at least one plant part of the production plant out of operation, wherein low-oxygen and oxygen-rich phosgene-containing exhaust gas flows are directed separately from one another in different phosgene decomposition directions and separately from one another&#x2014;at spatially different points&#x2014;into a combustion device, wherein plant parts that have not been taken out of operation are operated in a closed-circuit operating mode. The invention also relates to a production plant for producing a chemical product by reacting H-functional reactants with phosgene, which is suitable for being operated with the method according to the invention.

Production plant for producing a chemical product by reacting H-functional reactants with phosgene, and method for operating same with an interruption to production

The present invention relates to a process for preparing an isocyanate by reacting a primary amine with phosgene, comprising I) providing an amine solution, II) providing a phosgene solution, 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 in two or three stages, VI) further conversion of the liquid phase remaining after the last expansion stage in an indirectly heated reaction zone and VII) isolating the isocyanate from the reaction solution obtained therein.

Process for preparing an isocyanate by partly adiabatic phosgenation of the corresponding amine

A process for preparing an isocyanate by reacting a primary amine with phosgene. The process includes providing an amine solution and adjusting its temperature in a heat exchanger, providing a phosgene solution and adjusting its temperature in a heat exchanger, mixing the amine solution with the phosgene solution, 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, expanding the remaining liquid phase, further conversion of the liquid phase remaining after expansion in an indirectly heated reaction zone, and isolating the isocyanate from the obtained reaction solution. The temperature in the reaction zone and the temperature in the separation zone is adjusted by fixing a target value of 110&#xb0; C. to 145&#xb0; C. for the temperature of the reaction mixture and using the actual temperature of the reaction mixture for closed-loop control of the temperature of the solution of the primary amine and/or of the temperature of the solution of phosgene.

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Kölln-Reisiek, Germany

Juergen Spriewald