METHOD FOR PURIFYING CRUDE AQUEOUS SOLUTION OF ETHANOL

摘要

PURPOSE:To efficiently remove lipophilic impurities, especially 3C to 4C alcohols from a crude aqueous solution of ethanol. CONSTITUTION:The method is method to purity a crude aqueous solution of ethanol composed of (i) the first extraction step for subjecting the crude aqueous solution of ethanol to extraction treatment with an extracting agent composed of liquid gaseous carbon dioxide or gaseous carbon dioxide in the supercritical state in a pressurized state, (ii) a concentrating distillation step for feeding a raffinate obtained in the aforementioned first extraction step to a distillation column, obtaining an aqueous solution of ethanol at a high concentration and simultaneously taking out a distillate containing 3C to 4C alcohols as a side stream of the distillation column, (iii) the second extraction step for extracting the 3C to 4C alcohols contained in the side stream into an extract and (iv) a water washing step for recovering the ethanol contained in the extract in an aqueous phase.