Process to remove product alcohols from fermentation broth

1. A method for removing a product alcohol from a fermentation broth comprising:

(a) at least partially vaporizing a fermentation broth or a portion thereof to form one or more vapor streams, wherein the vaporizing comprises:

(i) vaporizing the fermentation broth or a portion thereof by one or more pre-flashes; and

(ii) vaporizing the fermentation broth or a portion thereof by a flash;

wherein the vapor streams comprise one or more components selected from product alcohol, water, and carbon dioxide;

(b) contacting the one or more vapor streams with an absorption liquid selected from fatty acids, fatty esters, 2-ethyl hexanol, isolauryl alcohol, isocetyl alcohol, oleyl alcohol, phenol, glycerol, glycol, dialkyl acetamide, N,N-bis(2-ethylhexyl) acetamide, di-isobutyl isobutyramide, tri-butyl phosphate, tri-isobutyl phosphate, potassium carbonate, and mixtures thereof, wherein at least a portion of the one or more vapor streams is absorbed into the absorption liquid to form an absorption liquid phase; and

(c) recovering the product alcohol from the absorption liquid phase.

2. The method of claim 1 , wherein pressure of the flash is lower than pressure of the one or more pre-flashes.

3. The method of claim 1 , further comprising sparging the one or more pre-flashes with a non-condensible gas.

4. The method of claim 1 , further comprising heating the fermentation broth of step (a)(i).

5. The method of claim 1 , further comprising compressing the non-absorbed vapor stream.

6. The method of claim 1 , further comprising distilling the absorption liquid phase comprising the one or more absorbed vapor streams to remove at least a portion of product alcohol, water, and carbon dioxide from the absorption liquid.

7. A method for removing a product alcohol from a fermentation broth comprising:

(a) at least partially vaporizing a fermentation broth or a portion thereof to form one or more vapor streams, wherein the vaporizing comprises:

(i) optionally vaporizing the fermentation broth or a portion thereof in a first pre-flash at a first pressure P1;

(ii) vaporizing the fermentation broth or a portion thereof in a second pre-flash at a second pressure P2; and

(iii) vaporizing the fermentation broth or a portion thereof in a flash at a third pressure P3;

wherein the one or more vapor streams comprise product alcohol, water, and carbon dioxide;

(b) contacting the one or more vapor streams with an absorption liquid selected from fatty acids, fatty esters, 2-ethyl hexanol, isolauryl alcohol, isocetyl alcohol, oleyl alcohol, phenol, glycerol, glycol, dialkyl acetamide, N,N-bis(2-ethylhexyl) acetamide, di-isobutyl isobutyramide, tri-butyl phosphate, tri-isobutyl phosphate, potassium carbonate, and mixtures thereof, under vacuum conditions wherein at least a portion of the one or more vapor streams is absorbed into the absorption liquid to form an absorption liquid phase; and

(c) recovering the product alcohol from the absorption liquid phase.

8. The method of claim 7 , wherein the third pressure P3 is lower than the second pressure P2.

9. The method of claim 7 , further comprising

distilling the absorption liquid phase comprising the one or more absorbed vapor streams to remove at least a portion of product alcohol, water, and carbon dioxide from the absorption liquid.

10. The method of claim 7 , further comprising sparging the first pre-flash with a non-condensible gas.

11. The method of claim 7 , further comprising heating the fermentation broth of step (a)(ii).

12. The method of claim 7 , further comprising compressing the non-absorbed vapor stream.