Bayer Intellectual Property Gmbh

Bayer Materialscience Ag

Mannesmann Aktiengesellschaft

Covestro Deutschland Ag

Friedhelm Risse

Pieter Ooms

Johan Vanden Eynde

Georg Ronge

Andre Düx

Thomas Pancur

Wim Wuytack

Arthur Susanto

Christoph Gürtler

Johann Rechner

Thomas Ernst Müller

Walter Leitner

Aurel Wolf

Burkhard Köhler

Ricarda Leiberich

Karl-Heinz Köhler

Ralph Schellen

Korbinian Krämer

Angelina Prokofieva

Franco Doro

Carsten Buchaly

Marcus Grünewald

Melchior Kahl

Ronge Georg

Thomas Ernst MÜLLER

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 relates to bimetallic complexes in which the ligand contains a salophen unit which complexes copper, manganese or cobalt and a phenanthroline unit which complexes palladium and the two systems are linked by a continuous conjugated system. The invention further relates to the use of these bimetallic complexes as catalysts for the oxidative carbonylation of aromatic hydroxy compounds to form diaryl carbonates, a process for preparing diaryl carbonates using the bimetallic complex as catalyst and also diaryl carbonates prepared by oxidative carbonylation of aromatic hydroxy compounds using the bimetallic complexes of the invention as catalysts.

Bimetallic complexes and the use thereof in producing diaryl carbonate

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

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

The present invention relates to a process for continuously preparing diaryl carbonates from dialkyl carbonates and at least one monohydroxyl compound in the presence of catalysts, and to the use thereof for preparation of polycarbonates. The alkylene glycol obtained in the preparation of the dialkyl carbonate used is recycled by oxidative carbonylation with carbon monoxide in the presence of a catalyst to give the cyclic alkylene carbonate which is in turn converted to the dialkyl carbonate. More particularly, the process utilizes the alkylene glycol obtained for the diphenyl carbonate preparation process (DPC process).

Process for preparing diaryl carbonates from dialkyl carbonates

A choke-bypass system is arranged upstream of the gas analyzer so as to generate a constant input pressure at the gas analyzer. The measurement range of the gas analyzer can be expanded considerably beyond the standard range while maintaining accuracy of measurement when the measurement gas is diluted with an inert gas above a given gas concentration threshold in such a way that the gas concentration in the gas analyzer remains constant. To this end, a dilution gas line (12) with a control valve (13) for continuous dilution of the measurement gas with the inert gas is connected to the choke-bypass system (1), (2), (3), (6). Further, the detector (3) of the gas analyzer is connected on the output side via a computer (10) with a dilution regulator (15) which readjusts the flow of inert gas via the control valve (13) in such a way that the amplified detector output signal is maintained at a given reference value, wherein the measurement gas flow is increasingly diluted as the measurement gas concentration increases. The dilution is then measured by a flow meter (14) arranged in the dilution gas line (12) and this measurement signal is processed together with the detector signal in a computer (10) connected with the detector (13) and dilution regulator (15) to form the analysis measurement.

Gas analyzer with regulated measurement gas feed and dynamic dilution of

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Kö'ln, Germany

Friedhelm Risse