Recovery of 3-hydroxpropionic acid

A method for recovering a composition enriched in 3-hydroxypropionic acid from a fermentation broth comprising 3-hydroxypropionic acid and/or salts thereof, the method comprising the steps of:

• (a) providing the fermentation broth having a pH of from about 2 to about 8 comprising:
• 3-hydroxypropionic acid and/or salts thereof, and
• sulfate ions and phosphate ions;
• (b) increasing the concentration of 3-hydroxypropionic acid and/or salts thereof in the fermentation broth of step (a) to from about 100 to about 500 grams of 3-hydroxypropionic acid equivalents per liter of broth by evaporating at least a portion of the liquid present in the fermentation broth;
• (c) acidifying the fermentation broth from step (b) to lower the pH to from about 1 to about 3 to form an aqueous solution comprising 3-hydroxypropionic acid;
• (d) reducing the total sulfate ion and phosphate ion concentration of the aqueous solution to produce a reduced ion aqueous solution comprising 3-hydroxypropionic acid;
• (e) distilling the reduced ion aqueous solution at a pH of from about 1 to about 3 by applying vacuum and heat to the reduced ion aqueous solution to form an aqueous distillation product comprising 3-hydroxypropionic acid, wherein the concentration of 3-hydroxypropionic acid in the reduced ion aqueous solution prior to distillation of step (e) is from about 20 percent by weight to about 80 percent by weight;
• (f) recovering the aqueous distillation product comprising 3-hydroxypropionic acid at a concentration of at least thirty percent by weight of the aqueous distillation product and wherein the aqueous distillation product comprises less than five parts by weight acrylic acid per one hundred parts by weight 3-hydroxypropionic acid present;
• (g) recovering a distillation bottom stream from distilling step (e), the distillation bottom stream comprising from about 5 percent to about 20 percent 3-hydroxypropionic acid of the total amount of the 3-hydroxypropionic acid present in the reduced ion aqueous solution of step (d);
• (h) applying vacuum and heat to the distillation bottom stream;
• and
• (i) recovering a second aqueous distillation product comprising 3-hydroxypropionic acid, wherein the second aqueous distillation product comprises less than about three parts by weight acrylic acid per one hundred parts by weight 3-hydroxypropionic acid present in the second aqueous distillation product.