FROM CARBON MONOXIDE AND HYDROGEN ANAEROBIC FERMENTATION PROCESSES USING A PRE-REACTOR/DEEP TANK REACTOR SYSTEM

• US 20130078687A1
• Filed: 09/23/2011
• Published: 03/28/2013
• Est. Priority Date: 09/23/2011
• Status: Active Grant

• Current Assignee: Synata Bio, Inc.
• Original Assignee: Coskata Energy
• Inventors: Hickey, Robert, Donnellan, Steven L.
• Granted Patent: US 8,980,597 B2
• Time in Patent Office: Days
• US Class Current: 435/136
• CPC Class Codes: C12P 7/04 acyclic
• CPC Class Codes: C12P 7/06 Ethanol, i.e. non-beverage
• CPC Class Codes: C12P 7/16 Butanols
• CPC Class Codes: C12P 7/24 containing a carbonyl group
• CPC Class Codes: C12P 7/40 containing a carboxyl group including Peroxycarboxylic acids
• CPC Class Codes: C12P 7/54 Acetic acid vinegar C12J
• CPC Class Codes: Y02E 50/10 Biofuels, e.g. bio-diesel

Abstract

Processes are disclosed for the low energy, anaerobic bioconversion of hydrogen and carbon monoxide in a gaseous substrate stream to oxygenated organic compounds such as ethanol by contact with microorganisms in a fermentation system with high conversion efficiency of both hydrogen and carbon monoxide. The processes of this invention use a pre-reactor and a deep, tank reactor in gaseous substrate flow sequence to obtain high conversion of gas substrate without undue risk of carbon monoxide inhibition.

Claims

1. A continuous process for the anaerobic bioconversion of a gas substrate comprising carbon monoxide, carbon dioxide and hydrogen in an aqueous menstruum containing microorganisms suitable for converting said substrate to oxygenated organic compound, said process comprising:

a. continuously supplying a gas feed comprising said gas substrate to a pre-reactor assembly comprising at least one pre-reactor for contact with an aqueous menstruum therein, said contacting being under conditions sufficient to convert in the pre-reactor assembly between about 10 and 40 percent of carbon monoxide in the gas feed to said oxygenated organic compound and provide a pretreated gas comprising unreacted carbon monoxide in a mole fraction less than that in the gas feed, unreacted hydrogen, and carbon dioxide in a mole fraction greater than that in the gas feed;

b. continuously supplying at least a portion of the pretreated gas to a deep, tank reactor as microbubbles having a diameter of less than about 500 microns for contact with an aqueous menstruum therein, said contacting being under conditions sufficient to provide a total, overall molar conversion of carbon monoxide and hydrogen contained in said gas feed in steps a and b to said oxygenated organic compound of at least about 80 percent; and

c. recovering oxygenated organic compound from the aqueous menstruum from the deep, tank reactor.

2. The process of claim 1 wherein the microbubbles have a diameter of between about 10 and 300 microns.

3. The process of claim 1 further comprising passing aqueous menstruum in the pre-reactor system to the deep, tank reactor.

4. The process of claim 1 wherein the pre-reactor system contains a single pre-reactor.

5. The process of claim 1 wherein the pre-reactor system contains at least one continuously stirred tank reactor.

6. The process of claim 1 wherein the pre-reactor system contains at least one bubble column reactor.

7. The process of claim 1 wherein the pre-reactor system contains at least one static mixer reactor.

8. The process of claim 1 wherein the pre-reactor system contains at least one jet loop reactor.

9. The process of claim 1 wherein the deep, tank reactor is a continuously stirred tank reactor.

10. The process of claim 1 wherein the deep, tank reactor is a bubble column reactor.

11. The process of claim 1 wherein between about 25 and 40 percent of the carbon monoxide contained in the feed gas to the pre-reactor assembly is converted to oxygenated organic compound.

12. The process of claim 11 wherein at least a portion pretreated gas from the pre-reactor assembly is subjected to process conditions to remove at least a portion of the carbon dioxide therein.

13. In a process for the production of oxygenated organic compound from gas feed comprising carbon monoxide, hydrogen and carbon dioxide by anaerobic fermentation in an aqueous menstruum under fermentation conditions, said liquid menstruum containing microorganism suitable for such production, using a deep fermentation reactor containing aqueous menstruum having a depth of at least 10 meters, the improvement comprising:

contacting the gas feed with aqueous menstruum in a pre-reactor assembly prior to being contacted with aqueous menstruum in the deep, tank reactor, said contacting in the pre-reactor assembly being under fermentation conditions and time sufficient to provide a pretreated gas to the deep, tank reactor that contains between about 5 and 30 mole percent carbon monoxide; and

supplying the gas feed to the deep, tank reactor as microbubbles having a diameter of less than about 500 microns.

14. The process of claim 13 wherein the pre-reactor assembly comprises a continuously stirred tank reactor.

15. The process of claim 13 wherein the deep, tank reactor is a bubble column reactor.

16. The process of claim 13 further comprising passing aqueous menstruum in the pre-reactor system to the deep, tank reactor.

17. The process of claim 13 wherein the back mix reactor zone comprises a static mixer reactor.

18. The process of claim 17 wherein the static mixer comprises a baffled pipe reactor.

19. The process of claim 13 wherein the pre-reactor assembly comprises a bubble column reactor.

20. The process of claim 13 wherein the deep, tank reactor is operating under non-steady state conditions.

21. The process of claim 19 wherein the non-steady state conditions comprise a start-up of the deep, bubble column reaction zone.