PROCESS FOR THE PREPARATION OF AN ALKANEDIOL AND A DIALKYL CARBONATE

摘要

An alkanediol and a dialkyl carbonate are prepared in a process comprising: (a) contacting an alkylene carbonate with an alkanol feedstock under transesterification conditions in a reactive distillation zone to obtain a top stream comprising dialkyl carbonate and the alkanol and a bottom stream comprising an alkanediol; (b) separating the top stream comprising dialkyl carbonate and the alkanol into an alkanol-rich stream and a dialkyl carbonate-rich stream; (c) recovering the dialkyl carbonate from the dialkyl carbonate-rich stream; and (d) recycling at least part of the alkanol-rich stream to the reactive distillation zone as part of the alkanol feedstock, wherein the alkanol-rich stream is split in at least two portions, and at least one portion is condensed and freed from compounds with a lower boiling point than the alkanol. The process is especially suitable for the production of propylene glycol and dimethyl carbonate from propylene carbonate and methanol.