Process for obtaining maleic anhydride by distillation

What is described is a process for obtaining maleic anhydride by distillation from a solution of maleic anhydride in a high-boiling absorbent which has been obtained by gas phase oxidation of a hydrocarbon and at least partial absorption of the oxidation products into the absorbent, by (i) introducing the solution into the side of a feed column with a rectifying section disposed above the feed point and a stripping section disposed below the feed point, (ii) providing an upper combining column which communicates with the upper end of the rectifying section and a lower combining column which communicates with the lower end of the stripping section, (iii) providing a draw column which communicates with the upper combining column and the lower combining column, (iv) drawing maleic anhydride off as a side draw from the draw column, and drawing off compounds having a lower boiling point than maleic anhydride at the top of the upper combining column and the high-boiling absorbent at the bottom of the lower combinin