Isolation of acrylic acid by means of a distillation column having a side offtake

1. A process for separating acrylic acid from a composition that comprises acrylic acid and an accompanying product, the process comprising:

first, contacting the composition with an aqueous liquid stream, thereby obtaining a liquid solution comprising acrylic acid, accompanying product, and water,

adding an entrainer to the liquid solution, thereby obtaining a heterogeneous minimum azeotrope with the water of the liquid solution,

separating the liquid solution by distillation into an overhead product comprising the minimum azeotrope and a bottom product comprising acrylic acid and the accompanying product,

separating the overhead product into water and a recirculatable entrainer, and

separating the bottom product by distillation into acrylic acid and the accompanying product,

wherein separating the bottom product comprises:

introducing and separating the bottom product in a distillation column that comprises a side offtake,

taking off high-boiling constituents of the accompanying product from a bottom of the distillation column,

taking off low-boiling constituents of the accompanying product from a top of the distillation column, and

taking off the acrylic acid from the side offtake,

wherein taking off the acrylic acid from the side offtake comprises taking off the acrylic acid from the side offtake in a liquid form,

wherein the distillation column is a dividing wall column comprising a dividing wall extending essentially vertically through the column,

wherein the dividing wall extends from a dividing wall-free top region to a dividing wall-free bottom region or to a floor of a bottom, and

wherein the distillation column further comprises a barrier wall that is constructed to close off a part of the distillation column located on a side of the side offtake from the dividing wall-free top region.

2. The process according to claim 1 , wherein the dividing wall extends from a height level above a level of the side offtake, and

wherein the dividing wall is configured to extend to a height level below a level of the bottom product introduced into the distillation column.

3. The process according to claim 1 , wherein the accompanying product comprises at least one component selected from the group consisting of acetic acid, water, and an aldehyde.

4. The process according to claim 1 , wherein the entrainer is an organic solvent having a boiling point of from 80 to 130° C.

5. The process of claim 4 , wherein the entrainer comprises at least one component selected from the group consisting of toluene, heptane, cyclohexane, and methylcyclohexane.

6. The process according to claim 1 ,

wherein the separating the overhead product into water and a recirculatable entrainer comprises distilling in a dewatering column such that a concentration of water in the bottom product is less than 0.5% by weight and a concentration of the entrainer in the bottom product is from 1 to 15% by weight.

7. The process of claim 6 , wherein the concentration of the entrainer in the bottom product after the separating the liquid solution is from 8 to 12% by weight.

8. The process of claim 6 , wherein the concentration of water in the bottom product after the separating the liquid solution is from 0.05% to 0.3% by weight.