Purification of chlorosilanes by means of distillation and adsorption

A process for distillative separation of a multicomponent chlorosilane mixture comprising a low boiler comprising dichlorosilane and at least one boron-, phosphorus- or arsenic-containing impurity, a middle boiler comprising trichlorosilane and at least one boron-, phosphorus- or arsenic-containing impurity, and a high boiler comprising silicon tetrachloride, the process comprising:

• a) supplying the multicomponent mixture to a first distillation column which is materially coupled to a second distillation column via connections;
• wherein the second distillation column comprises a horizontal dividing wall which separates a stripping section and a rectifying section of the second distillation column, wherein the second distillation column is materially coupled via connections to a third distillation column;
• b) feeding a first distillation column high boiler stream to the stripping section of the second distillation column and feeding a first distillation column low boiler stream to the rectifying section of the second distillation column;
• c) feeding a third distillation column low boiler vapor stream to the rectifying section of the second distillation column and feeding a third distillation column high boiler stream to the stripping section of the second distillation column;
• d) removing a bottoms fraction comprising silicon tetrachloride and a tops fraction comprising dichlorosilane from the second distillation column, and removing trichlorosilane via a side draw of the third distillation column;
• and
• e) passing at least one stream through an adsorber for removing the at least one boron-, phosphorus- or arsenic-containing impurity disposed in a connection for material coupling of the second distillation column and the third distillation column, and/or for material coupling of the second distillation column and the first distillation column.