Bayer Materialscience Ag

Covestro Deutschland Ag

Bayer Intellectual Property Gmbh

Andre Düx

Pieter Ooms

Georg Ronge

Johan Vanden Eynde

Johann Rechner

Kaspar Hallenberger

Wim Wuytack

Thomas Pancur

Carsten Buchaly

Peter Lehner

Ricarda Leiberich

Karl-Heinz Köhler

Friedhelm Risse

Arthur Susanto

Matthias Böhm

Rafael Warsitz

Knut Sommer

Korbinian Krämer

Ralph Schellen

Marcus Grünewald

Benie Marotz

Helmut Mothes

Franz-Ulrich Gehlen

Guenter Olf

Ronge Georg

Günther Olf

Vanden Johan Eynde

The present invention relates to a continuous process for producing lower dialkyl carbonates as a main product and alkylene glycol as a by-product by transesterification of a cyclic alkylene carbonate (e.g. ethylene or propylene carbonate) with lower alkyl alcohols in the presence of a catalyst and also the necessary purification of the dialkyl carbonate in a subsequent process step. For optimization of the economic efficiency and energy efficiency of the process, additional devices are used for intermediate heating of the internal liquid streams within the apparatus.

Process for producing dialkyl carbonates

The invention provides a process for preparing diaryl carbonates from dialkyl carbonates and aromatic hydroxyl compounds using at least two reaction columns, a process section for recovering the dialkyl carbonate used in the reaction and for removing the alcohol of reaction, one or more process steps for removing the by-products obtained in the process which have a boiling point between that of the dialkyl carbonate and that of the alkyl aryl carbonate formed during the preparation of the diaryl carbonate, and a process step for further purification of the diaryl carbonate obtained from the reaction columns.

Process for preparing diaryl carbonates from dialkyl carbonates

The invention relates to a process for preparing diaryl carbonates and/or alkyl aryl carbonates from dialkyl carbonates and aromatic hydroxy compounds using a reactive dividing wall column.

Process for preparing diaryl carbonates or alkyl aryl carbonates from dialkyl carbonates

The present invention relates to a continuous process for preparing lower dialkyl carbonates as main product and alkylene glycol as by-product by transesterification of a cyclic alkylene carbonate (e.g. ethylene carbonate or propylene carbonate) with lower alkyl alcohols in the presence of a catalyst and also the required purification of the dialkyl carbonate in a subsequent process step. To optimize the economics and energy efficiency of the process, additional devices are used for intermediate heating of the liquid streams in the apparatus.

Process for preparing dialkyl carbonates

Aromatic amines which have been obtained by reduction of aromatic nitro compounds are purified by mixing the crude amine obtained after phase separation with an aqueous, alkali metal hydroxide solution and subsequent distillation of this mixture over a distillation column. The distillation column has at least an upper and a lower rectifying part and a stripping part. The bottom product of the distillation column is partly to completely sluiced out and is partly evaporated in a main evaporator and at least one downstream re-evaporator and partly recycled back into the column.

Process for the purification of aromatic amines

The present invention relates to a continuous process for preparing lower dialkyl carbonates as main product and alkylene glycol as by-product by catalyzed transesterification of a cyclic alkylene carbonate (e.g. ethylene carbonate or propylene carbonate) with lower alcohols, where the reaction of the alkylene carbonate is carried out with an alcohol containing dialkyl carbonate in countercurrent, characterized in that introduction of a stream containing at least 99.5% by weight of alcohol takes place below the point of introduction for the alcohol containing dialkyl carbonate in a particular spacing ratio between the abovementioned points of introduction.

Process for preparing dialkyl carbonates from alkylene carbonates and alcohols

Processes comprising: reacting a dialkyl carbonate and an aromatic hydroxy compound in the presence of a transesterification catalyst in a first reaction column, the first reaction column comprising a top section, a bottom section, a rectifying section in an upper portion of the column and a reaction zone below the rectifying section; feeding a bottom product from the first reaction column to a further reaction column; the bottom product comprising a diaryl carbonate, an alkylaryl carbonate, or both, and residual unreacted dialkyl carbonate and aromatic hydroxy compound; the further reaction column comprising a top section, a rectifying section in an upper portion of the column and a reaction zone below the rectifying section; and reacting the residual unreacted dialkyl carbonate and aromatic hydroxy compound in the further reaction column; feeding a process stream to a distillation column, the process stream comprising a mixture of unreacted dialkyl carbonate and one or more reaction-product alcohols drawn from the first reaction column, the further reaction column, or both, such that the unreacted dialkyl carbonate is separated from the one or more reaction-product alcohols; and recycling the separated, unreacted dialkyl carbonate to the first reaction column; wherein the further reaction column comprises one or more condensers, and heat of condensation from the one or more condensers is fed back into the process.

Processes for preparing diaryl and/or alkylaryl carbonates from dialkyl carbonates

Processes comprising: transesterifying a dialkyl carbonate and an aromatic hydroxyl compound in the presence of a transesterification catalyst to provide a diaryl carbonate product comprising the transesterification catalyst as an impurity; subjecting the diaryl carbonate product to distillation in a first distillation column having an upper part and a lower part, wherein the upper part comprises a rectifying section and the lower part comprises a stripping section; and withdrawing a first sidestream from the first distillation column, wherein the first sidestream comprises a purified diaryl carbonate.

Processes for purifying diaryl carbonates

The invention provides a process for the preparation of diaryl carbonates and/or alkylaryl carbonates from dialkyl carbonates and aromatic hydroxy compounds using one or more intermediate condensers for improving heat integration.

Process for the preparation of diaryl carbonates or arylalkyl carbonates from dialkyl carbonates

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Brühl, Germany

Andre Düx