Abstract: A reactor system for producing polycarbonate includes a surface area in contact with a reaction mixture. The reaction mixture comprises a melt transesterification catalyst, a dihydroxy compound, a diaryl carbonate, and an phenolic byproduct. The surface area in contact with the reaction mixture contains one or more welds joining reactor system parts. All welds in contact with the reaction mixture join reactor system parts made from the same type of metal. If a filler metal is contained in the weld, the filler metal is made from the same type of metal as the metal parts joined by the weld.

Abstract: A reactor system for producing polycarbonate includes a surface area in contact with a reaction mixture. The reaction mixture comprises a melt transesterification catalyst, a dihydroxy compound, a diaryl carbonate, and an phenolic byproduct. The surface area in contact with the reaction mixture contains one or more welds joining reactor system parts. All welds in contact with the reaction mixture join reactor system parts made from the same type of metal. If a filler metal is contained in the weld, the filler metal is made from the same type of metal as the metal parts joined by the weld.

Abstract: An apparatus for preparing a dialkyl carbonate comprises means for reacting an alkanol, oxygen, carbon monoxide, and a catalyst to form a mixture comprising a dialkyl carbonate, an alkyl chloroformate, hydrochloric acid, water, carbon dioxide, and carbon monoxide; means for separating from the mixture a gaseous fraction comprising carbon monoxide and alkyl chloroformate; and means for removing alkyl chloroformate from the gaseous fraction.

Abstract: A method of preparing a dialkyl carbonate includes reacting an alkanol, oxygen, carbon monoxide, and a catalyst to form a mixture that includes a dialkyl carbonate and an alkyl chloroformate. The mixture is separated into a liquid fraction and a gaseous fraction, and alkyl chloroformate is removed from the gaseous fraction. Also described is an apparatus for carrying out the method. The method is particularly useful for preventing corrosion in a cold wash unit that removes further organic impurities from the gaseous fraction.

Abstract: An apparatus for preparing a dialkyl carbonate comprises means for reacting an alkanol, oxygen, carbon monoxide, and a catalyst to form a mixture comprising a dialkyl carbonate, an alkyl chloroformate, hydrochloric acid, water, carbon dioxide, and carbon monoxide; means for separating from the mixture a gaseous fraction comprising carbon monoxide and alkyl chloroformate; and means for removing alkyl chloroformate from the gaseous fraction.

Abstract: A method of preparing a dialkyl carbonate includes reacting an alkanol, oxygen, carbon monoxide, and a catalyst to form a mixture that includes a dialkyl carbonate and an alkyl chloroformate. The mixture is separated into a liquid fraction and a gaseous fraction, and alkyl chloroformate is removed from the gaseous fraction. Also described is an apparatus for carrying out the method. The method is particularly useful for preventing corrosion in a cold wash unit that removes further organic impurities from the gaseous fraction.