Patent ID: 8093437

Claim:
In an industrial process for the production of a diol in which a 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 said 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, then continuously feeding said high boiling point reaction mixture A B into a continuous multi-stage distillation column C for separating off material having a lower boiling point than that of the diol contained in said high boiling point reaction mixture A B , continuously obtaining the material having a lower boiling point than the diol as a column top component C T and a side cut component C S , and continuously obtaining the diol substantially not containing the material having a lower boiling point than that of the diol as a column bottom component C B , wherein the improvement comprises: (a) said continuous multi-stage distillation column C comprises a continuous multi-stage 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): 300 ≦L 1 ≦3000 (1) 50 ≦D 1 ≦700 (2) 3 ≦L 1 /D 1 ≦30 (3) 3 ≦n 1 ≦30 (4) 1000 ≦L 2 ≦5000 (5) 50 ≦D 2 ≦500 (6) 10 ≦L 2 /D 2 ≦50 (7) 20 ≦n 2 ≦100 (8) and D 2 ≦D 1 (9); (b) the enrichment section of said continuous multi-stage distillation column C has at least one chimney tray installed therein as an internal, said chimney tray having installed therein one or more chimneys each having an opening having a cross-sectional area S (cm 2 ) satisfying the formula (10): 200 ≦S≦ 1000 (10), and each of the chimneys being such that a height h (cm) from said opening of said chimney to a gas outlet of said chimney satisfies the formula (II): 10 ≦h≦ 80 (11); and (c) a side cut outlet is connected to a liquid collecting portion of said chimney tray of said continuous multi-stage distillation column C.