Improvements in and relating to the separation of hydrocarbons from alcohols by azeotropic distillation

摘要

Mixtures containing alcohols, other than methanol, and at least 5 per cent by weight of olefines and/or paraffins, e.g. the products of an "Oxo synthesis," are wholly or partly freed from the olefines and/or paraffins by submitting the mixture to distillation in a fractionating apparatus in the presence of methanol, whereby substantial amounts of the olefines and/or paraffins are removed as azeotropes with methanol. In an example, methanol (1 part by weight) was added to a mixture (4 parts) containing iso-octane (13 per cent), butanols (35 per cent) and nonanol (43 per cent), obtained by hydrogenation of the product resulting from the carbonylation of a mixture of propene and di-isobutene; and the mixture thus charged with methanol was fractionated at a reflux ratio of 10 : 1 in a still having an efficiency of 10 theoretical plates. The methanol-hydrocarbon azeotrope and excess methanol came over while the temperature at the head of the column was 56-70 DEG C, then followed the butanols at 100-120 DEG C, and finally nonanol at 185-200 DEG C. The hydrocarbons were separated as an upper layer from the 56-70 DEG C fraction by adding water to it. In another example, the separation of di-isobutene and iso-octane from n-propanol and nonanol, is described.