Bayer Materialscience Ag

Covestro Deutschland Ag

Bayer Intellectual Property Gmbh

Bayer Aktiengesellschaft

Bayer Materialscience, LLC

Covestro Intellectual Property Gmbh & Co. Kg

Wolfgang Lorenz

Rainer Bruns

Friedhelm Steffens

Stefan Wershofen

Bernd Pennemann

Andreas Karl Rausch

Thomas Knauf

Tim Loddenkemper

Fritz Pohl

Berthold Keggenhoff

Richard Adamson

Jürgen Münnig

Lars Padeken

Dietmar Wastian

Gerhard Wiechers

Klaus Biskup

Wolfgang Taube

Karsten Becker

Andreas Bulan

Rainer Weber

Herbert Stutz

Volker Michele

Peter Lehner

Heiko Beckhaus

Knut Sommer

Thomas Runowski

Matthias Böhm

Juergen Muennig

Friedhelm Kämper

Donald L Pferdehirt

Karl Schumacher

J&uuml;rgen M&uuml;nnig

Bill L Brady, Jr

Ulrich Hollmann

Gerhard Moormann

Lothar Weismantel

Matthias Boehm

Anke Hielscher

Andreas Rausch

Methods for the preparation of diisocyanates by the reaction of the corresponding primary diamines with phosgene in the gas phase are described, wherein the pressure in the diamine evaporation chamber during the transfer of the diamine into the gas phase is less than the pressure in the reaction chamber during the reaction to the diisocyanates, and wherein the pressure difference between the diamine evaporation chamber and the reaction chamber prior to the mixing of diamine and phosgene is overcome by a pressure-increasing element.

Method for preparing diisocyanates in the gas phase

The invention relates to a method for producing dinitrotoluene, comprising the following steps: a) nitrating toluene with a mixture of nitric acid and sulfuric acid and subsequently separating a sulfuric-acid-containing aqueous phase that arises in the nitration, wherein a raw dinitrotoluene is obtained, b) washing the raw dinitrotoluene in a water wash with neutral and/or alkaline washing water, wherein a pre-cleaned dinitrotoluene, which contains at least water in addition to dinitrotoluene, is obtained after the washing water used in the last wash has been separated, and c) separating the water from the pre-cleaned dinitrotoluene, d) collecting the waste water from steps a), b), and/or c), e) optionally extracting the collected waste water from step d) with toluene and returning the thus obtained organic phase to step a), f) freeing the collected waste water from step d), or, if the optional step e) is performed, the extracted waste water from step e), of toluene in a toluene stripper, wherein a toluene-containing exhaust gas flow is obtained, g) feeding at least one exhaust gas flow from steps a), b), c), d), e), or f) into an exhaust gas condenser and removing the toluene contained in the at least one exhaust gas flow in said exhaust gas condenser, wherein the method comprises the following further step: h) feeding the exhaust gas flow arising in step g) after the condensing out of the toluene to a thermal exhaust air cleaning, wherein nitrogen is added to the exhaust gas flow to be fed to the exhaust gas condenser or to the exhaust gas flow leaving the exhaust gas condenser, wherein preferably a nitrogen concentration in the exhaust gas flow of at least 0.1 vol % is set, especially preferably of at least 0.5 vol %.

Exhaust gas cleaning in a method for continuously producing dinitrotoluene

This invention relates to a process for operating a gas phase phosgenation plant () to form an isocyanate () by reacting an amine () with phosgene (), in which the gas phase phosgenation plant is shut down by first stopping the amine stream and still maintaining the phosgene stream. After a period of time which corresponds to at least 10 times the residence time of phosgene () in the main parts of the gas phase phosgenation plant () in regular operation, calculated from the time at which the amine inflow has been completely stopped, the feed of phosgene is also stopped. An inert gas stream () is maintained through the amine and phosgene feeding devices and through all the other essential parts of the gas phase phosgenation plant () during the shutdown.

Process for operating a gas phase phosgenation plant

This invention relates to a process for operating a gas phase phosgenation plant () to form an isocyanate () by reacting an amine () with phosgene (), in which the gas phase phosgenation plant is started up by first charging the plant with phosgene. At the same time as, or after the first charge of phosgene, the amine supply devices are rendered inert using a hot inert gas stream (). Then, amine is admixed for the first time. In this way and by maintaining a pressure drop in the amine and phosgene devices to the mixing zone, the back mixing of phosgene into the amine-containing reactant stream during start-up is prevented.

Method for operating a gas-phase phosgenation plant

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

The invention relates to a device (R) for producing phosgene by reacting chlorine and carbon monoxide in the presence of a fixed-bed catalyst, comprising a) a tube bundle, which is arranged inside a reactor jacket () and which has a plurality of reaction tubes (), which are arranged substantially parallel to each other and which extend from a lower tube sheet () to an upper tube sheet (), and b) a coolant space for a cooling fluid, which coolant space surrounds the reaction tubes () and is defined by the lower tube sheet (), the upper tube sheet (), and the reactor jacket (), wherein the device is characterized in that the tube bundle is enclosed by an annular-space sheet (), which defines an inner annular space () for the passage of the cooling fluid and which is arranged at a distance from both the lower tube sheet () and the upper tube sheet (), wherein an outer annular space () for feeding liquid cooling fluid through is formed between the annular-space sheet () and the reactor jacket (), which outer annular space is in fluid connection with the inner annular space (). The invention further relates to a method for producing phosgene by means of such a device.

Device and method for producing phosgene

The invention relates to a method for producing diamines and polyamines of the diphenylmethane series in which, by using a coalescence auxiliary in the phase separation of the process product obtained in the scrubbing of the neutralized crude product, the fraction of water and thus also of water-soluble impurities in the organic MDA-containing phase is reduced. According to the invention, the coalescence auxiliary used is a filter bed made of coalescence fiber material. The di- and polyamines of the diphenylmethane series obtained after distillative purification of this MDA-containing organic phase are exceptionally suitable for the preparation of the corresponding isocyanates.

Process for the preparation of di- and polyamines of the diphenylmethane series

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 invention relates to a method for producing diamines and polyamines of the diphenylmethane series, wherein first aniline and formaldehyde are reacted in the absence of an acidic catalyst to form a reaction mixture containing animal and water and, after the water has been separated the aminal is reacted by acid catalysis to form a reaction mixture containing diamines and polyamines of the diphenylmethane series, wherein the separation of the water from the aminal is supported by the use of a coalescence aid. According to the invention, a filter bed made front coalescence fiber material is used an coalescence aid.

Method for producing diamines and polyamines of the diphenylmethane series

The invention relates to a process for the preparation of aromatic amines in the liquid phase by catalytic hydrogenation of the corresponding nitroaromatic compounds in at least two reaction spaces connected in series, wherein at least one reaction space is operated isothermally and at least the reaction space connected downstream thereof is operated adiabatically, and in preferred embodiments the sudden adiabatic temperature change is used for monitoring the reaction.

Method for producing aromatic amines in the liquid phase

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.

Aromatic isocyanates are produced by reacting one or more aromatic primary amines with phosgene in the gas phase. The phosgene and primary aromatic amine(s) are reacted at a temperature above the boiling temperature of the amine(s) in a reactor having a reaction space which is essentially rotationally symmetric to the direction of flow. The flow fate, averaged over the cross-section, of the reaction mixture along the axis of the essentially rotationally symmetric reaction space in the section of the reaction space in which the conversion of the amine groups into isocyanate groups is between 4 and 80% is not more than 8 m/sec. The flow rate averaged over the cross-section of the reaction mixture along the axis of the essentially rotationally symmetric reaction space in the section of the reaction space in which the conversion of the amine groups into isocyanate groups is 4 to 80% is always below the flow rate averaged over the cross-section at the start of this section.

Growing community of inventors

Dormagen, Germany

Wolfgang Lorenz