Recovering ethanol sidedraw by separating crude product from hydrogenation process
A process for producing ethanol is disclosed, comprising the steps of hydrogenating acetic acid in a reactor in the presence of a catalyst to form a crude ethanol product, separating at least a portion of the crude ethanol product in a column into a first distillate comprising ethanol and a first residue comprising acetic acid and water, wherein a substantial portion of the water in the crude ethanol product that is fed to the column is removed in the first residue, and separating a portion of the ethanol mixture stream to the second distillation column to yield an ethanol product sidedraw, second residue comprising water and a second distillate comprising ethyl acetate. The water content of the ethanol product sidedraw may be further reduced to yield a stream having reduced water content.
1. A process for producing ethanol, comprising:
hydrogenating acetic acid in a reactor in the presence of a catalyst to form a crude ethanol product;
separating at least a portion of the crude ethanol product in a first distillation column to yield a first residue comprising acetic acid and a first distillate comprising ethanol, ethyl acetate, and water;
removing water from at least a portion of the first distillate to yield an ethanol mixture stream comprising less than 10 wt. % water; and
separating a portion of the ethanol mixture stream in a second distillation column to yield an ethanol product sidedraw, a second residue comprising water and a second distillate comprising ethyl acetate.
2. The process of claim 1 , wherein the ethanol product sidedraw is enriched in ethanol compared to the second residue.
3. The process of claim 1 , further comprising reducing the water content of the ethanol product sidedraw to yield an ethanol product stream having a reduced water content.
4. The process of claim 3 , wherein the reducing step uses an adsorption unit.
5. The process of claim 3 , wherein the reducing step comprises separating at least a portion of the ethanol product sidedraw with a membrane into a permeate stream comprising water and a retentate stream comprising ethanol and having a lower water concentration than the ethanol product sidedraw.
6. The process of claim 5 , wherein the retentate stream comprises less than 3 wt. % water.
7. The process of claim 5 , wherein the retentate stream is a fuel grade ethanol comprising less than 2 wt. % water.
8. The process of claim 1 , wherein at least 40% of the ethanol in the ethanol mixture stream is removed in the ethanol product sidedraw.
9. The process of claim 8 , wherein the ethanol product sidedraw comprises less than 500 wppm acetic acid and less than 100 wppm ethyl acetate.
10. The process of claim 1 , wherein the ethanol product sidedraw is withdrawn below a feed location of the ethanol mixture stream to the second distillation column.
11. The process of claim 1 , wherein the ethanol product sidedraw is an industrial grade ethanol comprising less than 12 wt. % water.
12. A process for producing ethanol, comprising:
hydrogenating acetic acid in a reactor in the presence of a catalyst to form a crude ethanol product;
separating at least a portion of the crude ethanol product in a column into a first distillate comprising ethanol and a first residue comprising acetic acid and water, wherein a substantial portion of the water in the crude ethanol product that is fed to the column is removed in the first residue; and
separating a portion of the first distillate in the second distillation column to yield an ethanol product sidedraw, a second residue comprising water and a second distillate comprising ethyl acetate.
13. The process of claim 12 , wherein the second residue further comprises acetic acid.
14. The process of claim 12 , wherein the ethanol product sidedraw is enriched in ethanol compared to the second residue.
15. The process of claim 12 , further comprising reducing the water content of the ethanol product sidedraw to yield an ethanol product stream having a reduced water content.
16. The process of claim 15 , wherein reducing the water content uses an adsorption unit.
17. The process of claim 15 , wherein the reducing step comprises separating at least a portion of the ethanol product sidedraw with a membrane into a permeate stream comprising water and a retentate stream comprising ethanol and having a lower water concentration than the ethanol product sidedraw.
18. The process of claim 17 , wherein the retentate stream comprises less than 3 wt. % water.
19. The process of claim 17 , wherein the retentate stream is a fuel grade ethanol comprising less than 2 wt. % water.
20. The process of claim 12 , wherein at least 40% of the ethanol in the first distillate is removed in the ethanol product sidedraw.
21. The process of claim 12 , wherein the ethanol product sidedraw comprises less than 500 wppm acetic acid and less than 100 wppm ethyl acetate.
22. The process of claim 12 , wherein the ethanol product sidedraw is withdrawn below a feed location of the first distillate to the second distillation column.
23. The process of claim 12 , wherein the ethanol product sidedraw is an industrial grade ethanol comprising less than 12 wt. % water.