Patent ID: 7226527

Claim:
A process for recovering crude 1,3-butadiene from a C 4 fraction by extractive distillation using a selective solvent, which is carried out in a dividing wall column in which a dividing wall is arranged in the longitudinal direction of the column to form a first subregion, a second subregion and a lower common column region and which is preceded by an extractive scrubbing column, wherein the C 4 fraction (1) is fed to the first subregion a stream taken off at the top from the first subregion of the dividing wall column is fed to the extractive scrubbing column in its upper region, a countercurrent extraction is carried out in the extractive scrubbing column by treatment with a first substream of the selective solvent in the upper region of the extractive scrubbing column, the components of the C 4 fraction which are less soluble than 1,3-butadiene in the selective solvent are taken off at the top of the extractive scrubbing column, a bottom stream from the extractive scrubbing column is recirculated to the upper region of the first subregion of the dividing wall column, a second substream of the selective solvent is fed to the dividing wall column in the middle region of the second subregion, selective solvent laden with 1,3-butadiene together with components of the C 4 fraction which are more soluble than 1,3-butadiene in the selective solvent is taken off from the bottom of the dividing wall column, and the product is taken off at the top from the second subregion of the dividing wall column as crude 1,3-butadiene.