Purifying ethyl alcohol by distillation

950,619. Purifying ethanol by distillation. BERGWERKSGESELLSCHAFT HIBERNIA A.G. Sept 7, 1960, No. 30898/60. Addition to 900,627. Heading BIB. Crude ethanol is purified in a distillation system comprising a purifying column 2 and a rectifying column 12, the crude ethanol being introduced through pipe 1 into the top section of column 2 and a stream of hot water, withdrawn from the base of column 12, being fed into column 2 at the same level as the feed-pipe 1. Live steam is introduced into the base of column 2. Vapours comprising aldehydes, ether and other impurities pass overhead from column 2; and aqueous ethanol (7-8%) is withdrawn from the base. This aqueous ethanol is passed through pipe 9 to column 12 wherein it is rectified ; and pure 94% ethanol is withdrawn through pipe 18. An aqueous solution of sodium hydroxide may be added at about the middle of column 12 in order to maintain the water in the base of the column at a pH value of 8 to 12. The overhead condensate from column 12 is partly refluxed to this column, the remainder being passed through pipe 15 to column 2. The vapours from the top of column 2 pass to condenser 3 ; part of the condensate is refluxed to column 2, and the remainder is distilled in column 6. The top of column 6 is supplied, through pipe 17, with some of the hot water from the base of column 12. The overhead from column 6, which is condensed in condenser 7, contains 5% alcohol, 70% water and 25% ether, acetaldehyde and other impurities. The liquid drawn off from the bottom of column 6 is introduced into the top of column 2 at the same level as the crude alcohol. The process may be used for purifying fermentation alcohol, or ethanol produced by the catalytic hydration of ethylene.