Method and device for extractive distillation

A process for fractionating a starting mixture of two or more components by extractive distillation using a selective solvent in a dividing wall column, wherein

• the process is carried out in a dividing wall column having a dividing wall aligned in a longitudinal direction of the column and extending to an upper end of the column and dividing an interior of the column into a first region, a second region, and a lower combined column region,
• the starting mixture is fed into the first region, a first top stream is taken off from the first region, and a second top stream is taken off from the second region, with each of the streams having a prescribed specification,
• the selective solvent is introduced in an upper part of the first region or in an upper part of the second region, and
• flow of solvent into the first region or flow of solvent into the second region are set so that each of the prescribed specifications for the top streams are met.