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, a total sulfate ion and phosphate ion concentration, and an amount of micro-organism cells;

(b) acidifying the fermentation broth to lower the pH to from about 1 to about 3 to form an aqueous solution comprising 3-hydroxypropionic acid, an amount of micro-organism cells, and an amount of gypsum precipitate;

(c) 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 of step (c) to from about 30 percent by weight to about 70 percent by weight of the solution by evaporating a portion of the water present in the reduced ion aqueous solution;

(d) 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

(e) 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 fermentation broth has a pH of from about 2.5 to about 4.5 in step (a).

3. 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 (b).

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

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

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

7. The method of claim 1 , wherein the distillation step (d) is carried out by heating the reduced ion aqueous solution at a temperature above 100° C. for a time less than five minutes.

8. The method of claim 1 , wherein the distillation step (d) is carried out by heating the reduced ion aqueous solution at a temperature above 130° C. for a time less than two minutes.

9. The method of claim 1 , wherein the concentration of 3-hydroxypropionic acid 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.

10. The method of claim 1 , wherein the concentration of 3-hydroxypropionic acid and/or salts thereof in the fermentation broth of step (a) is from about 60 to about 150 grams of 3-hydroxypropionic acid equivalents per liter of broth.

11. The method of claim 1 , wherein the total sulfate ion and phosphate ion concentration in the reduced ion aqueous solution from step (c) is less than about 5000 ppm.

12. The method of claim 11 , wherein the step (c) of reducing the total sulfate ion and phosphate ion concentration of the aqueous solution is carried out by utilizing an ion exchanger.

13. The method of claim 1 , wherein the concentration of 3-hydroxypropionic acid in the reduced ion aqueous solution prior to distillation of step (d) is from about 25 percent by weight to about 70 percent by weight.

14. The method of claim 1 , wherein

the total sulfate ion and phosphate ion concentration is reduced to less than about 5000 ppm in step (c);

the concentration of 3-hydroxypropionic acid in the aqueous distillation product of step (d) is from about 30 percent by weight to about 60 percent by weight; and

the aqueous distillation product recovered in step (e) contains less than about 1 part by weight acrylic acid per one hundred parts by weight 3-hydroxypropionic acid.

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

(i) 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 a portion of the water present in the fermentation broth at a broth temperature of from about 60° C. to about 100° C.

16. The method of claim 15 , wherein the concentration of 3-hydroxypropionic acid and/or salts thereof in the fermentation broth is increased to from about 250 to about 400 grams of 3-hydroxypropionic acid equivalents per liter of broth.

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

18. The method of claim 17 , wherein the reducing step (k) takes place prior to the acidifying step (b).

19. The method of claim 1 , further comprising the step (l) of reducing the amount of gypsum present in the aqueous solution comprising 3-hydroxypropionic acid prior to step (c).