Patent ID: 7393992

Claim:
A continuous process for separating a mixture of hydrocarbons which has been obtained by extractive distillation of a C 4 fraction using a selective solvent and the hydrocarbons from the C 4 fraction which are more readily soluble in the selective solvent than are the butanes and the butenes, which comprises feeding the mixture into a first distillation column in which it is separated into a stream which is taken off at the top and comprises 1,3-butadiene and propyne, and a bottom stream comprising 1,3-butadiene, 1,2-butadiene and acetylenes, with the proportion of 1,3-butadiene in the bottom stream from the first distillation column being regulated in such a way that it is at least sufficiently high to dilute the acetylenes to outside the range in which there is a risk of spontaneous decomposition, and passing the stream taken off from the top of the first distillation column to a second distillation column and separating it into a stream which is taken off at the top and comprises propyne, and a bottom stream comprising pure 1,3-butadiene in the second distillation column.