Process for removing an alkanol impurity from an organic carbonate stream
View Patent ↗The invention relates to a process for removing an alkanol impurity from a stream containing an organic carbonate and the alkanol impurity, comprising contacting the stream with a catalyst to effect reaction of the alkanol impurity with the organic carbonate.
1. A process for making a diaryl carbonate, comprising:
(a) reacting an alkylene carbonate and an alkanol in the presence of a transesterification catalyst to obtain a product mixture containing unconverted alkylene carbonate, unconverted alkanol, di(C1-C5)alkyl carbonate, alkanediol and an ether alkanol impurity;
(b) separating unconverted alkylene carbonate and alkanediol from the product mixture to obtain a top stream containing unconverted alkanol, di(C1-C5)alkyl carbonate and the ether alkanol impurity;
(c) recovering the alkanediol;
(d) separating unconverted alkanol from the top stream containing unconverted alkanol, di(C1-C5)alkyl carbonate and the ether alkanol impurity obtained in step (b) to obtain a bottom stream containing di(C1-C5)alkyl carbonate and the ether alkanol impurity,
(e) contacting the bottom stream containing di(C1-C5)alkyl carbonate and the ether alkanol impurity obtained in step (d) with a catalyst to effect reaction of the ether alkanol impurity with the di(C1-C5)alkyl carbonate to provide a stream containing di(C1-C5)alkyl carbonate from which the ether alkanol impurity has been removed, and
(f) contacting the stream containing di(C1-C5)alkyl carbonate obtained in step (e) with an aryl alcohol in the presence of a transesterification catalyst to provide the diaryl carbonate.
2. The process according to claim 1 , wherein the diaryl carbonate is diphenyl carbonate and the aryl alcohol is phenol.