Patent ID: 8049028

Claim:
In an industrial process for separating out a dialkyl carbonate, comprising the steps of: continuously feeding starting materials into a continuous multi-stage distillation column A in which a homogeneous catalyst is present by taking a cyclic carbonate and an aliphatic monohydric alcohol as the starting materials; carrying out reactive distillation in said column A; continuously withdrawing a high boiling point reaction mixture A B containing a produced diol from a lower portion of said column A in a liquid form; 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 said column A in a gaseous form; continuously feeding said low boiling point reaction mixture A T into a continuous multi-stage distillation column B; and carrying out separation by distillation into a column top component B T having the aliphatic monohydric alcohol as a main component thereof and a column bottom component B B having the dialkyl carbonate as a main component thereof, wherein the improvement which comprises: said continuous multi-stage distillation column B 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 (8); 500≦L 1 ≦3000 (1) 100≦D 1 ≦1000 (2) 2 ≦L 1 /D 1 ≦30 (3) 10≦n 1 ≦40 (4) 700≦L 2 ≦5000 (5) 50≦D 2 ≦800 (6) 10 ≦L 2 /D 2 ≦50 (7), and 35≦n 2 ≦100 (8).