Patent GB-678191-A (GB)
Title: Process for the separation of mixtures containing hydrocarbons and alcohols by distillation
IPC: C07C37/80
Filed: 1950-09-06
Abstract: Olefines produced by Fischer-Tropsch synthesis or by cracking, are oxidized by water gas in the presence of cobalt catalysts under a pressure of 200 atmos., and the products are then hydrogenated under the same pressure.  A fraction of the hydrogenated products, boiling from 230 DEG  to 345 DEG  C., is extracted with methanol containing 0.5 per cent of water, to give a mixture containing 83 per cent alcohols and 17 per cent hydrocarbons. This mixture was distilled with 1,3-butane-diol, and the vapours were passed through a rectifying column, and then condensed.  The condensate separated into two layers.  The upper layer, which comprised hydrocarbons, was partly refluxed and partly withdrawn from the system.  The lower layer consisting of butane-diol with traces of the synthetic alcohols, was continuously returned to the bottom section of the column.  Synthetic alcohols having a purity of 99.5 per cent were obtained at the end of the fractionation, after removal therefrom of the added diol.ALSO:Hydrocarbons are separated from monohydric alcohols or phenols by submitting the mixture to fractional distillation in the presence of a polyhydric alcohol, e.g. a glycol, whereby the hydrocarbons are taken-off overhead.  The process may be applied to the mixtures obtained by the catayltic hydrogenation of carbon monoxide, OXO-synthesis, carbonization of coal, or reduction of fatty acids.  The mixture to be separated is advantageously divided into fractions which are separately distilled with the polyhydric alcohol.  The mixture may be subjected to preliminary purification by solvent-extraction.  The polyhydric alcohol may boil above or below the mixture to be separated.  In an example, a 75 DEG -160 DEG C fraction separated from the products of the catalyptic hydrogenation of carbon monoxide, containing 50 per cent monohydric alcohols and 50 per cent hydrocarbons, was distilled in a fractionating column; and hexane-diol 1, 6 (6 pt. 250 DEG C) was introduced into the top of the column, the quantity of diol being about half the volume of the feed-fraction.  Hydrocarbon vapours came over from the top of the column; and a mixture of the monohydric alcohols and the diol was obtained as bottoms.  The monohydric alcohols were distilled off from the diol in a second column; and the diol was recycled to the top of the first column. In another example, olefines (obtained by Fischer-Tropsch synthesis or by cracking) are oxidized with water-gas, and the oxidation-products are reduced with hydrogen.  A fraction of the hydrogenated products, with a boiling-range of 230 DEG -345 DEG C was then separated, and this was extracted with methanol containing 0.5 per cent water.  The extract (after separation of methanol and water by distillation) contained 83 per cent alcohols and 17 per cent hydrocarbons.  This mixture was introduced into a still together with butane-diol 1, 3.  The vapours leaving the still were passed through a column, and then condensed. The condensate separated into two layers.  The upper layers, which comprised hydrocarbons, was partly refluxed and partly withdrawn from the system.  The lower layer consisting of diol with traces of synthetic alcohols, was continuously returned to the bottom section of the column. Alcohols having a purity of 99.5 per cent were obtained at the end of the fractionation, and after removal therefrom of the auxiliary diol.  The fractionation may be carried out at atmospheric pressure, or the pressure may be reduced to 20 m m. Hg. absolute.  Ethylene glycol and other diols may also be used as auxiliary liquids; also glycerine and other triols.