Covestro Deutschland Ag

Covestro Intellectual Property Gmbh & Co. Kg

Martin Ehrig

Reinhard Halpaap

Josef Sanders

Armin Schymura

Dietmar Wastian

Ralph Weber

Manfred Kobylka

Manfred Keller-Killewald

Frank Richter

Tim Loddenkemper

Michael Merkel

Robert Maleika

Jan Morbach

Johannes Leonhäuser

Dirk Weiβenberg

Christian Morten Jens

Maria Carrascosa Mas

Elsa Karoline Schadlich

Sebastian Hoch

Peter Lehner

Martin Schiffhauer

Dirk Weißenberg

Elsa Karoline SCHÄDLICH

The present invention relates to a process for distillative purification of a crude isocyanate obtained by phosgenation of the corresponding amine in a distillation apparatus under vacuum to obtain the corresponding isocyanate, characterized in that at least one liquid ring compressor is used to generate the vacuum in the distillation apparatus, a particular operating liquid is used for the at least one liquid ring compressor, the pressure p on the suction side of the at least one liquid ring compressor is 10 to 200 mbar(a), the operating temperature of the at least one liquid ring compressor is −17° C. to +15° C. and the operating liquid at the exit from the at least one liquid ring compressor has an AC value of less than 35 000 ppm, to a corresponding use of at least one liquid ring compressor for generating a vacuum in an apparatus for distillation of a crude isocyanate and to a corresponding process for operating a liquid ring compressor for providing the vacuum for distillative purification of an isocyanate obtained by phosgenation of the corresponding amine in a distillation apparatus to obtain the corresponding isocyanate.

Process for the distillation of isocyanates

The present invention relates to a method for producing purified phosgene vapor, comprising the following steps: 1) providing a gas flow obtainable from the reaction of chlorine with carbon monoxide and comprising phosgene and carbon monoxide; 2) one-stage or multi-stage condensation of the gas flow and separation of non-condensable residue gases; 3) one-stage or multi-stage evaporation of the liquid phosgene obtained in step 2) and optional overheating of the produced phosgene vapour, wherein there is an energy integration between one or more of the condensation steps of step 2) and one or more of the evaporation steps in step 3) and the pressure in the last condensation step is between &#x2265;0.2 and &#x2264;6.0 bar higher than in the first evaporation step.

Energy-efficient method for providing a purified phosgene vapor

The invention relates to a method for producing 1,5-pentanediisocyanate (PDI) by reacting 1,5-pentanediamine (PDA) with phosgene in the gas phase.

Method for producing 1,5-pentanediisocyanate in the gas phase

A method for processing hydrogen chloride from isocyanate preparation comprises the steps: a) providing hydrogen chloride; b) purifying the hydrogen chloride provided; and furthermore step c) or step d): c) bringing the purified hydrogen chloride into contact with water and/or with hydrochloric acid which is not saturated with respect to uptake of hydrogen chloride, d) further processing the purified hydrogen chloride to chlorine by partial oxidation. The hydrogen chloride provided in step a) contains organic and/or nitrogen-containing impurities and in step b) the purification is carried out by bringing hydrogen chloride into contact with hydrochloric acid which is saturated to the extent of &#x2265;90% with respect to uptake of hydrogen chloride at least in a first gas scrubber () and circulating this hydrochloric acid at least partially through the first gas scrubber ().

Method for processing hydrogen chloride from isocyanate preparation

The invention relates to a method for producing the isomers 1,3- and/or 1,4-xylylene diisocyanates by reacting the corresponding 1,3- and/or 1,4-xylylene diamines with phosgene in the gaseous phase.

Method for producing xylylene diisocyanates in the gaseous phase

Growing community of inventors

Leverkusen, Germany

Martin Ehrig