Bayer Materialscience Ag

Covestro Deutschland Ag

Bayer Intellectual Property Gmbh

University of Cape Town

Carl Von Ossietzky Universitat Oldenburg

Andreas Karl Rausch

Wolfgang Lorenz

Rainer Bruns

Thomas Knauf

Stefan Wershofen

Tim Loddenkemper

Bernd Pennemann

Matthias Ehlers

Charles Bjoerndahl

Friedhelm Steffens

Dietmar Wastian

Michael Merkel

Peter Lehner

Alexandre Racoes

Carlos Alvarez Herrero

Francisco Munoz Velasco

Fritz Pohl

Klaus Biskup

Joachim Ritter

Jürgen Münnig

Dirk Manzel

Peter Plathen

Christian Steffens

Jeffrey Bolton

Matthias Böhm

Manfred Keller-Killewald

Lars Padeken

Wolfgang Dohmen

Wulf Dietrich

Michael Christian Maximilian Claeys

Eric Wilhelmus Josephus Van Steen

Frank Roessner

Marcus Grünewald

Juergen Munnig

Christoph Blöcher

Dietrich Wulf

Michael Christian Maximillian Claeys

Charles BJÖRNDAHL

The present invention relates to a method for operating a phosgene generator for producing phosgene by reacting carbon monoxide with chlorine in the gas phase on an activated carbon catalyst arranged in a reaction chamber, in which method, after a predefinable operating period, the phosgene production is at least temporarily interrupted by shutting down the phosgene generator over a shutdown period and, after a predefinable downtime, is resumed by starting up the phosgene generator over a start-up period, wherein the method is characterized in that the activated carbon catalyst, before the phosgene generator is started up, is freed of chlorine by adding carbon monoxide so that, during the start-up period, a maximum concentration of chlorine in the gas stream immediately downstream of the reaction chamber of 1000 ppmv is not exceeded. The invention also relates to the use of the phosgene thus obtained in the production of polycarbonate and isocyanates.

Method for starting up and shutting down a phosgene generator

The invention relates to a method for preparing isocyanates by the phosgenation of the corresponding amines in which problems resulting from the formation of deposits in apparatuses of the reaction segment during activation (starting) and deactivation (termination) of the method can be prevented by processing measures, in particular ensuring that there is a surplus of phosgene relative to the phosgenating amine during the critical starting and termination steps of the method.

Process for preparing isocyanates

The invention relates to a method for preparing isocyanates by phosgenating the corresponding amines, wherein low-boiling secondary components, excess phosgene, and the co-product hydrogen chloride are separated from the crude liquid isocyanate stream, which is obtained after the phosgenation has occurred, within a maximum of 60 minutes, and wherein the crude liquid isocyanate stream is not exposed to temperatures above 250&#xb0; C. until said separation.

Method for producing isocyanates

Meta-toluene-diisocyanate is produced by reacting meta-toluenediamine with phosgene in the gas phase. The meta-toluenediamine to be vaporized for use in this phosgenation process must contain less than 0.5 wt. % of toluenediamine residue, a total of less than 0.2 wt. % of ammonia and cycloaliphatic amines, and less than 20 ppm of heavy metals. At least 0.1 wt. % of the liquid meta-toluenediamine being to be vaporized must not be vaporized. This non-vaporized content of the meta-toluenediamine must not be fed to the phosgenation reactor.

Process for the preparation of isocyanates in the gas phase

The invention relates to a process for the preparation of isocyanates by reaction of the corresponding amines with phosgene in the gas phase, wherein a diluent containing between 90.0000% by weight and 99.9999% by weight of substances which are inert in the phosgenation process and between 0.0001% by weight and 10.0000% by weight of oxygen is present during the conversion of the amine into the gas phase and the molar ratio of amine to oxygen (O) is &#x2267;1,000:1.

Method for producing isocyanates in the gas phase

The present invention relates to a process and a plant for the production, in particular the continuous production, of nitrobenzene by means of adiabatic nitration of benzene with nitric acid in the presence of sulfuric acid, in which, following the nitration, a multi-stage concentration of the sulfuric acid is carried out by means of heating at a pressure that is reduced as compared with ambient pressure, and wherein the heating takes place using the heat generated in the adiabatic nitration of benzene.

Method and system for producing nitrobenzene

Isocyanates are produced by reacting a primary amine with phosgene in the gas phase. In this process, the amine is vaporized and then superheated prior to introduction into the reactor. The amine is superheated to a temperature at least 10&#xb0; C. above dew point before entry into the reactor. A pressure difference between the vaporizer and entry into the reactor of from 1 to 500 mbar is maintained.

The invention relates to a method for treating wastewater containing nitroaromatics and nitrohydroxyaromatics, as for example arises in the production of nitroaromatics or in the production of nitrohydroxyaromatics, by a two-stage method consisting of pre-reduction and wet oxidation.

Method for treating wastewaters

The invention relates to a process for the continuous production of nitrobenzene by nitration of benzene with a mixture of nitric acid and sulfuric acid under adiabatic conditions, in which unreacted benzene is separated from the crude product obtained after phase separation before washing thereof, using the adiabatic heat of reaction.

Method for producing nitrobenzene by adiabatic nitriding

A process is provided for the production of hydrocarbons from synthesis gas wherein the synthesis gas is fed to a reactor in which a catalyst acts on the feed at a temperature of between 160&#xb0; C. and 400&#xb0; C. and a pressure of between 1 bar and 5 bar. The feed includes a compound containing one or both nitrogen and phosphorus added to the reactor with the synthesis gas. The compound containing nitrogen typically constitutes at least 1 vol % and preferably of the order of 4 to 20 vol % or more of the feed. The carbonaceous gas may be carbon monoxide with a ratio of hydrogen to carbon monoxide in the synthesis gas of from 0.5:1 to 5:1. The catalyst is preferably a supported cobalt catalyst and may be modified with a promoter. The process produces an enhanced proportion of olefins, in the hydrocarbons produced.

Process for the production of hydrocarbons including olefins from synthesis gas

Nitrobenzene is continuously produced by nitration of benzene with mixed acid under adiabatic conditions. In this process, the pressure upstream of the nitration reactor is from 14 bar to 40 bar above the pressure in the gas phase of the phase separation apparatus used to separate crude nitrobenzene and waste acid.

Process for the continuous preparation of nitrobenzene

The invention relates to a mixer reactor of the rotor-stator type. This mixer reactor comprises a substantially rotationally symmetric housing which has a distributing chamber, a mixing chamber, a front plate that modifies the cross-section of the housing between these two chambers, and there are separate inlets into the mixing chamber for at least two substances and an outlet for removing the mixed material or product. The inlet for the first substance is provided in the axis of rotation of the mixing chamber. Two or more channels are aligned radially outward from this inlet, and the first substance is transported through these channels and into the mixing chamber. The inlet for the at least second substance is constructed in the form of a plurality of openings in the front plate, these inlet openings being are arranged rotationally symmetrically to the axis of rotation. Each of these inlet openings for the at least second substance has a corresponding pin which can be displaced in the axial direction.

Process and mixing unit for the preparation of isocyanates by phosgenation of primary amines

This invention relates to a process for the continuous preparation of nitrobenzene. This process comprises the adiabatic nitration of benzene with a mixture of sulfuric acid and nitric acid, in which the sum of the concentrations in the reaction zone of the metal ions which form sparingly soluble metal sulfates is less than 900 mg/l, based on the volume of the aqueous phase which contains sulfuric acid.

Process for the preparation of nitrobenzene by adiabatic nitration

Growing community of inventors

Kaarst, Germany

Andreas Karl Rausch