Recovery of 3-hydroxypropionic acid

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

(a) providing the aqueous fermentation broth having a pH of from about 2 to about 8 comprising:

3-hydroxypropionic acid and/or salts thereof, water, and an amount of micro-organism cells greater than zero cells, 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 water present in the fermentation broth;

(c) acidifying the fermentation broth to lower the pH to from about 1 to about 3 to form an aqueous solution comprising 3-hydroxypropionic acid and gypsum precipitate;

(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;

increasing the concentration of 3-hydroxypropionic acid in the reduced ion aqueous solution to from about 30 percent by weight to about 70 percent by weight by evaporating a portion of the water present in the reduced ion aqueous solution;

(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; and

(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.

2. The method of claim 1 , wherein the concentration of 3-hydroxypropionic acid and/or salts thereof in the fermentation broth is increased to from about 140 to about 400 grams of 3-hydroxypropionic acid equivalents per liter of broth.

3. The method of claim 1 , wherein the evaporation of water in (b) takes place at a broth temperature of from about 60° C. to about 100° C.

4. The method of claim 1 , wherein the evaporation of the water in the reduced ion aqueous solution takes place at a solution temperature of from about 60° C. to about 100° C.

5. The method of claim 1 , further comprising the step (h) of reducing the amount of micro-organism cells present in the fermentation broth prior to step (d).

6. The method of claim 5 , wherein the reducing step (h) takes place prior to the acidifying step (c).

7. The method of claim 1 , further comprising the step (i) of reducing the amount of the gypsum precipitate present in the aqueous solution comprising 3-hydroxyproionic acid prior to step (d).

8. The method of claim 1 , wherein:

the total sulfate ion and phosphate ion concentration is reduced to less than about 3000 ppm in step (d);

the concentration of 3-hydroxypropionic acid in the reduced ion aqueous solution prior to distillation of step (e) is from about 30 percent by weight to about 70 percent by weight;

the distillation step (e) comprises heating the reduced ion aqueous solution to a temperature of from about 130° C. to about 150° C.;

the distillation step (e) is carried out at a pressure of from about 10 to about 35 mm Hg absolute; and

the aqueous distillation product recovered in step (f) contains less than about 0.5 parts by weight acrylic acid per one hundred parts by weight 3-hydroxypropionic acid.

9. The method of claim 1 , wherein the fermentation broth has a pH of from about 2 to about 5 in step (a).

10. The method of claim 1 , wherein the pH of the fermentation broth is lowered to a pH of from about 1.5 to about 2.5 in step (c).

11. The method of claim 1 , wherein the 3-hydroxypropionic acid is recovered in step (f) at a concentration of at least about forty percent by weight of the aqueous distillation product.

12. The method of claim 1 , wherein the aqueous distillation product recovered in step (f) contains less than about three parts by weight acrylic acid per one hundred parts by weight 3-hydroxypropionic acid present.

13. The method of claim 1 , wherein the aqueous distillation product recovered in step (f) contains less than about 1 part by weight acrylic acid per one hundred parts by weight 3-hydroxypropionic acid.

14. The method of claim 1 , wherein the distillation step (e) comprises heating the reduced ion aqueous solution to a temperature of from about 120° C. to about 180° C.

15. The method of claim 1 , wherein the step (e) of distilling the reduced ion aqueous solution is carried out by equipment selected from wiped film evaporation equipment, rising film evaporator equipment, thin film evaporation equipment, molecular distillation equipment, and falling film distillation equipment.

16. The method of claim 1 , wherein the concentration of 3-hydroxypropionic add and/or salts thereof in the fermentation broth of step (a) is from about 30 to about 200 grams of 3-hydroxypropionic acid equivalents per liter of broth.

17. The method of claim 1 , wherein the step (d) of reducing the total sulfate ion and phosphate ion concentration of the aqueous solution is carried out by utilizing an ion exchanger.

18. The method of claim 1 , wherein the concentration of 3-hydroxypropionic acid in the reduced ion aqueous solution prior to distillation of step (e) is from about 30 percent by weight to about 60 percent by weight.

19. The method of claim 1 , further comprising prior to the acidifying step (c):

(i) increasing the concentration of 3-hydroxypropionic acid and/or salts thereof in the fermentation broth of step (a) to from about 150 to about 350 grams of 3-hydroxypropionic acid equivalents per liter of broth by evaporating a portion of the water present in the fermentation broth at a broth temperature of from about 60° C. to about 100° C.

20. The method of claim 19 , wherein the concentration of 3-hydroxypropionic acid and/or salts thereof in the fermentation broth is increased to from about 200 to about 330 grams of 3-hydroxypropionic acid equivalents per liter of broth.