Bayer Aktiengesellschaft

Covestro Deutschland Ag

Bayer Antwerpen

Gabriel Denecker

Domien Sluyts

Johan Vanden Eynde

Kaspar Hallenberger

Ricarda Leiberich

Karl-Heinz Köhler

Florian Lipski

Henning Kahnis

Korbinian Krämer

Werner Verhoeven

Weerachanan Somhom

Manfred Schmidt

Claus H Wulff

Gottfried Zaby

Wolfgang Jakob

Tony Van Osselaer

J&uuml;rgen Heuser

Wolfgang Arlt

Hugo Obermann

Johan Vaes

Joel Leuridan

Roland Putseys

Stefaan De Vos

Thomas Bamberger

Georg Spott

Pol Bamelis

Willy Van Herck

Ludo Claes

Guido Lahousse

Henri Vandebroek

Pol Balmelis

Jan De Roos

Jean-Marie Biot

Karl-Heinz KÖHLER

The invention concerns a method for producing diaryl carbonates from monophenols and phosgene or chloroformic acid aryl esters in the presence of at least one optionally substituted pyridine or the hydrochloride salt thereof as catalyst, and the recovery and reinjection thereof back into the method. The method is carried out at least partially in a liquid phase without the use of an additional solvent, the catalyst being separated by means of distillation and recovered.

Method for producing diaryl carbonates

The invention concerns a method for producing diaryl carbonates from monophenols and phosgene or chloroformic acid aryl esters in the presence of an optionally substituted pyridine or the hydrochloride salt thereof as catalyst, and the recovery and reinjection thereof back into the method. The method is carried out at least partially in a liquid phase without the use of an additional solvent, the catalyst being separated by means of crystallization and recovered.

The present application relates to a method for the continuous production of diaryl carbonate from phosgene and of at least one monohydroxy compound (monophenol) in the presence of catalysts, and to the use thereof for the production of polycarbonates.

Method for producing diaryl carbonate

Nitrate-containing (contaminated) solutions are reduced with SO gas in the presence of an at least equimolar amount of NH or ammonium salt.

Process for the reduction of concentration of nitrates and/or nitrogen-containing compounds by means of SO2

The invention relates to a process for drying polymeric powders and polymeric agglomerates, in particular thermoplastic aromatic polycarbonate or other thermoplastic polymers such as, for example, acrylonitrile-butadiene-styrene copolymer, in the melt, whereby thermoplastic polymeric powders or polymeric agglomerates containing water or solvent or both are freed from adhering moisture and contained solvent, accompanied by melting, in an apparatus provided with rotating baffles for cleaning the walls of the apparatus and for distribution and transport of the material being dried, by heat input through the walls or through the rotating baffles or both as well as by heat input as a result of shearing action. The process of drying and that of melting for the subsequent granulation are thereby combined.

Process for drying polymeric powders and polymeric agglomerates

The invention relates to a process for stabilizing the molecular weight of high molecular weight, optionally branched polyarylene sulfides prepared by reaction of aromatic dihalogen compounds and, optionally, aromatic trihalogen or tetrahalogen compounds and, optionally, polymer-chain-terminating monomers with alkali metal sulfides and/or alkali metal hydrogen sulfides at elevated temperature in aprotic polar solvents, characterized in that, after the desired molecular weight has been reached, alkali metal sulfides and/or alkali metal hydrogen sulfides present in excess are at least partly reacted with acids to form the alkali metal salts of the acids and hydrogen sulfide.

Process for stabilizing the molecular weight of linear or optionally

High-grade titanium dioxide is produced by

Process for the production of high-grade titanium dioxide by sulfate

Tar-like residues from the preparation of 2-mercaptobenzothiazole can be used by heating them at temperatures above 200.degree. C. for at least 1 hour and separating off the aniline and benzothiazole thereby formed.

Process for working up tars containing 2-mercaptobenzothiazole

An improved work-up of aqueous mother liquors which originate from the oxidative preparation of benzothiazolylsulphenamides and which contain unreacted amine or a low-boiling alcohol employed as solubilizer, or both, the work-up being carried out in such a fashion that the mother liquor is saturated by additives until two phases form, the phases are separated from one another, the aqueous phase is extracted with further alcohol or amine, amine, alcohol and the extracted components are isolated from the combined organic phases, and amine or alcohol dissolved in the aqueous phase is removed therefrom by distillation.

Process for the work-up of the mother liquors from the preparation of

A process for the working up of ammonium sulphate-containing effluent which is contaminated with organic compounds and optionally also ammonium nitrate, comprising evaporating the effluent to produce water vapor which is removed, a concentrated liquid and a crystal suspension, thickening the suspension to obtain solid ammonium sulphate which is removed and liquid which is recycled to an earlier stage, subjecting the concentrated liquid from evaporation to an optional vacuum cooling crystallization to obtain water vapor which is removed and a crystal suspension from which a concentrated liquid is separated off, advancing the concentrated liquid from the evaporation stage or from the vacuum cooling crystallization stage to a crystallizer, introducing ammonia into the crystallizer to decrease the solubility of the ammonium sulphate, thickening the ammoniacal crystal suspension to obtain ammonium sulphate solids which are removed and ammoniacal mother liquor which is advanced to a distillation step for recovery of ammonia.

Process for working up effluent containing ammonium sulphate

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Kalmthout, Belgium

Gabriel Denecker