METHOD OF SEPARATING METHANOL FROM LOW BOILING ALIPHATIC ESTERS AND WATER BY AZEOTROPIC DISTILLATION WITH A HYDROCARBON

摘要

Methanol is separated from a mixture comprising methanol, a low-boiling ester, e.g. methyl acrylate, which forms an azeotrope with methanol, an organic substance having a boiling point above the ester, and water by feeding the mixture through pipe 4 into distillation column I which contains a saturated C 1- C 7 hydrocarbon, e.g. cyclohexane in the vapour state. Vapours comprising methanol and hydrocarbon leave the head of column 1 and pass to condenser 10. The condensate flows to cool decanter 8 where two liquid layers are formed. The hydrocarbon layer and part of the methanol layer are returned through pipe 7 to column 1 and the remainder of the methanol layer is passed to distillation column 23 where it is freed from residual hydrocarbon and, possibly, ester. Pure methanol is withdrawn through pipe 26. The liquid which reaches the base of column 1 is passed to a hot decanter 3, where the liquid separates into an aqueous layer and an organic layer. The organic layer is fractionated in column 2, and the overhead vapours (methanol + water) is returned to column i through pipe 13. The mixture of ester and higher-boiling organic substance, withdrawn from the base of column 2, is separated in column 17. The aqueous layer from decanter 3 is fractionated in column 18. Vapours of ester and water flows from the head of column 18 into column 1 and water is discharged from the base of column 18. A polymerization inhibitor, such as hydroquinone, may be introduced into the system through pipes 27, 28. An aqueous solution of a copper salt may be introduced into the lower part of column 1 and the upper part of column 2.