Patent ID: 10112886

Abstract:
The present invention relates to a method for purifying a crude benzoic acid (32) containing 5 to 20% by weight of byproducts and 80 to 95% by weight of benzoic acid, by means of distillation, wherein the distillation is performed in a plant comprising a first distillation system (54), which comprises a divided wall column (10). Preferably, the divided wall column (10) comprises: an upper portion having an upper undivided section (12) for concentrating low-boiling components, wherein the low-boiling components have a lower boiling point than benzoic acid, and an outlet for removal of the low-boiling components from the column (10), a lower portion having a lower undivided section (14) for concentrating high-boiling components, wherein the high-boiling components have a higher boiling point than benzoic acid, and an outlet for removal of the high-boiling components from the column (10), and a central portion arranged between the upper portion and the lower portion having at least one vertical dividing wall (20) for dividing the central portion into at least one feed section (16) and at least one withdrawal section (18), the feed section (16) having an inlet for the feed of crude benzoic acid (32) and the withdrawal section having a side draw outlet for the purified benzoic acid (34).