PROCESS FOR INDUSTRIAL PRODUCTION OF HIGH-PURITY DIOLS

It is an object of the present invention to provide a specific apparatus and process for producing a high-purity diol by taking a cyclic carbonate and an aliphatic monohydric alcohol as starting materials, continuously feeding the starting materials into a continuous multi-stage distillation column A in which a catalyst is present, carrying out reactive distillation in the column A, continuously withdrawing a low boiling point reaction mixture A T containing a produced dialkyl carbonate and the aliphatic monohydric alcohol from an upper portion of the column A in a gaseous form, continuously withdrawing a high boiling point reaction mixture A B containing a produced diol from a lower portion of the column A in a liquid form, continuously feeding the high boiling point reaction mixture A B into a continuous multi-stage distillation column C, distilling off material having a lower boiling point than that of the diol contained in the high boiling point reaction mixture A B as a column top component C T and / or a side cut component C s so as to obtain a column bottom component C B , continuously feeding the column bottom component C B into a continuous multi-stage distillation column E, and obtaining the diol as a side cut component E s from a side cut outlet of the continuous multi-stage distillation column E. Moreover, it is an object to thus provide a specific industrial apparatus and industrial production process that are inexpensive and, for example, enable the high-purity diol to be produced in an amount of not less than 1 ton / hr stably for a prolonged period of time (e.g. not less than 1000 hours, preferably not less than 3000 hours, more preferably not less than 5000 hours). The above objects can be attained by using a continuous multi-stage distillation column E having a specified structure, and withdrawing a liquid component from the side cut outlet, which is installed at the bottom of a chimney tray having a specified structure installed in an enrichment section of the continuous multi-stage distillation column E.