Patent ID: 7884251

Claim:
A process for separating out a by-produced alcohol in a case of continuously mass-producing an alkyl aryl carbonate mainly on an industrial scale using a reactive distillation system of continuously feeding a dialkyl carbonate and an aromatic monohydroxy compound into a continuous multi-stage distillation column A in which a catalyst is present and carrying out transesterification reaction and distillation simultaneously in the column A, comprising the steps of continuously withdrawing a low boiling point reaction mixture A T containing 1.5 to 10% by weight of said by-produced alcohol, 50 to 85% by weight of the dialkyl carbonate and 10 to 40% by weight of the aromatic monohydroxy compound from an upper portion of the column 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 low boiling point mixture B T having not less than 90% by weight of said by-produced alcohol and all or most of the remainder of the low boiling point mixture B T being dialkyl carbonate continuously withdrawn from an upper portion of the column in a gaseous form and a high boiling point mixture B B continuously withdrawn from a lower portion of the column in a liquid form, which comprises: said continuous multi-stage distillation column B is a distillation column comprising a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 ≦500 (2) 2≦L 1 /D 1 ≦30 (3) 10≦n 1 ≦40 (4) 700≦L 2 ≦5000 (5) 50≦D 2 ≦400 (6) 10 ≦L 2 /D≦ 50 (7) 35≦n 2 ≦100 (8) wherein an amount of said alcohol separated out is not less than 200 kg/hr.