GB686278A - Separating n-propyl alcohol from secondary butyl alcohol by extractive distillation - Google Patents

Abstract

n-Propyl alcohol is separated from a mixture containing it and secondary butyl alcohol, e.g. a mixture obtained by fractionating the products of the partial oxidation of butane or a mixture of propane and butane, by subjecting the alcohol mixture butane, by subjecting the alcohol mixture to extractive distillation using as solvent, methyl naphthalene, dimethyl naphthalene, diphenyl, diphenyl ether, or the eutectic mixture of diphenyl and diphenyl ether, whereby n-propyl alcohol is obtained as the overhead product. The proportion of solvent employed is between 5 to 50 volumes for each volume of alcohol mixture. The still bottoms may be distilled to recover the secondary butyl alcohol and other alcohols therein, and the solvent remaining may then be recycled for use in the extractive distillation. In an example, 100 parts by volume per hour of a mixture containing 42 per cent by weight of n-propyl alcohol, 8 per cent of secondary butyl alcohol, 26 per cent of isobutyl alcohol, and 12 per cent of n-butyl alcohol together with high boiling impurities, are introduced at the 15th tray from the bottom of a 45 tray column provided with a reboiler, condenser and reflux line; and 560 parts by volume per hour of the eutectic mixture of diphenyl ether and diphenyl containing 26.5 per cent by weight of diphenyl, are introduced at the top of the column. A reflux ratio of 5:1 is maintained. The overhead product comprises pure n-propyl alcohol.