Patent ID: 8071819

Claim:
An industrial process for the production of a high-purity diol in which a high-purity diol is produced 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 said 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 said high boiling point reaction mixture A B into a continuous multi-stage distillation column C, distilling off material having a lower boiling point than the diol contained in said 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, wherein: (a) said continuous multi-stage distillation column E comprises a distillation column comprising a stripping section having a length L 1 (cm), an inside diameter D 1 (cm) and an internal with a number of stages n 1 thereinside, and an enrichment section having a length L 2 (cm), an inside diameter D 2 (cm) and an internal with a number of stages n 2 thereinside, wherein L 1 , D 1 , n 1 , L 2 , D 2 , and n 2 satisfy the following formulae (1) to (9): 400â‰¦L 1 â‰¦3000â€ƒâ€ƒ(1) 50â‰¦D 1 â‰¦700â€ƒâ€ƒ(2) 2 â‰¦L 1 /D 1 â‰¦50â€ƒâ€ƒ(3) 3â‰¦n 1 â‰¦30â€ƒâ€ƒ(4) 600â‰¦L 2 â‰¦4000â€ƒâ€ƒ(5) 100â‰¦D 2 â‰¦1000â€ƒâ€ƒ(6) 2 â‰¦L 2 /D 2 â‰¦30â€ƒâ€ƒ(7) 5â‰¦n 2 â‰¦50â€ƒâ€ƒ(8) and D 1 â‰¦D 2 (9); (b) the enrichment section of said continuous multi-stage distillation column E has at least one chimney tray as an internal installed therein, said chimney tray having installed therein at least two chimneys each having an opening having a cross-sectional area S (cm 2 ) satisfying the formula (10): 50â‰¦Sâ‰¦2000â€ƒâ€ƒ(10), and each of the chimneys being such that a height h (cm) from the opening of the chimney to a gas outlet of the chimney satisfies the formula (11): 20â‰¦hâ‰¦100â€ƒâ€ƒ(11); and (c) the diol is continuously withdrawn in a liquid form from the side cut outlet, which is connected to a liquid collecting section of said chimney tray of said continuous multi-stage distillation column E.