Method for controlling undesirable byproducts formation caused by contaminating organisms in the production of ethanol from syngas

1. A process for the metabolic conversion of substrate to light oxygenates comprising:

a. contacting in a fermentation liquid containing said substrate with microorganisms capable of bioconverting the substrate to light oxygenates under fermentation conditions, said fermentation liquid being susceptible to a presence of contaminating bacteria capable of producing at least one of butyrate or butanol from said substrate or from said light oxygenates through a butyryl CoA enzyme; and

b. providing in said fermentation liquid a sufficient amount of a crotonate-like compound to restrict the production of said at least one of butyrate or butanol by a butyryl-CoA dehydrogenase, wherein the crotonate-like compound is represented by the structural formula:

R 2 (R 3 )C═C(H)C(O)R 1   I.

or

R 2 -A-C(O)R 1   II.

wherein:

R 1 is —OH, —OR 5 , or —N(R 4 ) 2 , wherein R 5 is hydrocarbyl and each R 4 may be the same or different and is hydrogen or hydrocarbyl;

R 2 is hydrogen, —NH 2 , —OH or —CX 3 wherein each X may be the same or different and is hydrogen or halogen;

R 3 is hydrocarbyl of 1 to 18 carbons which may be unsubstituted or substituted with —OH, alkoxyl of 1 to about 6 carbons, or halogen;

A is an aromatic moiety having 5 or 6 ring atoms which may be all carbon atoms or may be heterocyclic with one hetero atom selected from the group consisting of oxygen and nitrogen which aromatic moiety has —R 2 at the 2 position wherein —R 2 is as defined above and which aromatic moiety may be unsubstituted or substituted at one or more of the higher carbon positions with (i) hydrocarbyl of 1 to 18 carbons which may be substituted with —OH, alkoxyl of 1 to about 6 carbons, or halogen, (ii) —OR 6 wherein R 6 is lower alkyl, (iii) —N(R 7 ) 2 wherein each R 7 is the same or different and is hydrogen or hydrocarbyl or (iv) halogen;

with the proviso that in structural formula I, at least one of R 2 and R 3 is or is substituted with haloalkyl and that in formula II at least the 2 or 3 carbon position of the aryl moiety is substituted with an electron withdrawing group selected from the group consisting of halogen and haloalkyl.

2. A method of restricting the production of butyrate and/or butanol in an anaerobic fermentation of a gas substrate comprising at least one of CO and a mixture of CO 2 with hydrogen, the method comprising:

a. passing the gas stream to an anaerobic fermentation zone containing at least one species of anaerobic microorganism capable of producing an liquid product comprising light oxygenates;

b. converting at least a portion of the gas stream to the liquid product by contact of the microorganism in the fermentation zone with the gas stream;

c. providing at least one crotonate-like compound in the fermentation liquid in an amount effective to restrict production of butyrate and/or butanol by butyryl-CoA dehydrogenase, said crotonate-like compound represented by the structural formula

R 2 (R 3 )C═C(H)C(O)R 1   I.

or

R 2 -A-C(O)R 1   II.

wherein:

R 1 is —OH, —OR 5 , or —N(R 4 ) 2 , wherein R 5 is hydrocarbyl and each R 4 may be the same or different and is hydrogen or hydrocarbyl;

R 2 is hydrogen, —NH 2 , —OH or —CX 3 wherein each X may be the same or different and is hydrogen or halogen;

R 3 is hydrocarbyl of 1 to 18 carbons which may be unsubstituted or substituted with —OH, alkoxyl of 1 to about 6 carbons, or halogen;

A is an aromatic moiety having 5 or 6 ring atoms which may be all carbon atoms or may be heterocyclic with one hetero atom selected from the group consisting of oxygen and nitrogen which aromatic moiety has —R 2 at the 2 position wherein —R 2 is as defined above and which may be unsubstituted or substituted at one or more of the higher carbon positions with (i) hydrocarbyl of 1 to 18 carbons which may be substituted with —OH, alkoxyl of 1 to about 6 carbons, or halogen, (ii) —OR 6 wherein R 6 is lower alkyl, (iii) —N(R 7 ) 2 wherein each R 7 is the same or different and is hydrogen or hydrocarbyl or (iv) halogen;

with the proviso that in structural formula I, at least one of R 2 and R 3 is or is substituted with haloalkyl and that in formula II at least the 2 or 3 carbon position of the aryl moiety is substituted with an electron withdrawing group selected from the group consisting of halogen and haloalkyl;

d. withdrawing fermentation liquid containing the liquid product from the fermentation zone; and

e. recovering the liquid product from the fermentation liquid.

3. The method of claim 2 wherein the fermentation zone contains at least one of a homoacetogenic or heteroacetogenic microorganism for the production of a liquid product comprising ethanol or acetate and is contaminated with a butyrogenic microorganism that produces at least one of butyrate or butanol.

4. The method of claim 3 wherein the fermentation zone contains a homoacetogenic microorganism that comprises at least one of Clostridium autoethanogenum, Clostridium ljungdahlii, Clostridium ragsdalei , and Clostridium coskatii and the fermentation zone produces a liquid product comprising at least one of acetate and ethanol.

5. The method of claim 2 wherein the fermentation zone comprises a suspended cell bioreactor that suspends the anaerobic microorganism in the fermentation liquid and the at least one crotonate-like compound enters the bioreactor with a media mixture that flows into the fermentation liquid.

6. The method of claim 2 wherein the fermentation zone comprises a membrane supported bioreactor.

7. The method of claim 2 wherein the crotonate-like compound is represented by the formula:

R 2 (R 3 )C═C(H)C(O)R 1   III.

or

R 2 -A-C(O)R 1   IV.

wherein:

in formula III, R 2 is —OH, —NH 2 or —CX 3 wherein X is halogen and R 3 is —CX 3 wherein X is halogen, and

in formula IV, the aryl is phenyl and at least one of the 2 and 3 position carbons of the phenyl moiety is —CX 3 wherein X is halogen.

8. The method of claim 7 wherein the at least one crotonate-like compound comprises at least one of alkyl 4,4,4-trifluoro-3-(trifluoromethyl)crotonate; 4,4,4-trifluoro-3-(trifluoromethyl)crotonic acid; 4,4,4-trifluoro-3-(trifluoromethyl)crotonamide; 2-trifluoromethylbenzoic acid; 2-trifluoromethylbenzamide; alkyl 2-trifluoromethylbenzoate; 3-trifluoromethylbenzoic acid; 3-trifluoromethylbenzamide; alkyl 3-trifluoromethylbenzoate; 2-amino-3-trifluoromethylbenzoic acid; 2-amino-3-trifluoromethylbenzamide; alkyl 2-amino-3-trifluoromethylbenzoate; 3-trifluoro-4-methoxybenzoic acid; 3-trifluoro-4-methoxybenzamide; alkyl 3-trifluoro-4-methoxybenzoate; 3-trifluoromethyl-4-fluorobenzoic acid; 3-trifluoromethyl-4-fluorobenzamide; alkyl 3-trifluoromethyl-4-fluorobenzoate; 3-trifluoromethyl-5-trifluoromethylbenzoic acid; 3-trifluoromethyl-5-trifluoromethylbenzamide; alkyl 3-trifluoromethyl-5-trifluoromethylbenzoate; 3-amino substituted crotonates such as 4,4,4-trifluoro-3-aminocrotonic acid; 4,4,4-trifluoro-3-aminocrotonamide; and alkyl 4,4,4-trifluoro-3-aminocrotonate wherein the alkyl is 1 to 4 carbons.

9. The method of claim 2 wherein the anaerobic microorganism comprises a heteroacetogen that produces liquid products having at least 2 to 3 carbon atoms and the liquid product comprises at least one of acetic acid, ethanol, propanol, and propionic acid.

10. The method of claim 2 wherein the at least one crotonate-like compound is added in an amount sufficient to produce a concentration of at least 10 ppm by mass in the fermentation liquid.

11. The method of claim 2 wherein the at least one crotonate-like compound is added to the fermentation zone as single dose in an amount of at least 50 ppm by mass.

12. The method of claim 2 wherein the fermentation zone comprises a membrane supported bioreactor and the at least one crotonate-like compound is added to the fermentation liquid.

13. The method of claim 2 wherein the fermentation zone contains more than one species of anaerobic microorganisms.

14. The method of claim 13 wherein the crotonate-like compound is represented by the formula:

R 2 (R 3 )C═C(H)C(O)R 1   III.

or

R 2 -A-C(O)R 1   IV.

wherein:

in formula III, R 2 is —OH, —NH 2 or —CX 3 wherein X is fluorine, and R 3 is —CX 3 wherein X is fluorine, and

in formula IV, the aryl is phenyl and at least one of the 2 and 3 position carbons of the phenyl moiety is —CX 3 wherein X is fluorine.

15. The method of claim 13 wherein the fermentation zone contains a homoacetogenic microorganism for the production of a liquid product comprising ethanol and a butyrogenic microorganism that produces at least one of butyrate or butanol.

16. The method of claim 13 wherein the anaerobic microorganism comprises a heteroacetogen that produces liquid products having at least 2 to 3 carbon atoms and the liquid product comprises at least one of acetic acid, ethanol, propanol, and propionic acid.

17. The method of claim 13 wherein the at least one crotonate-like compound is added to the fermentation liquid at a concentration of at least 10 ppm.

18. A method of producing a product comprising a C 2 oxygenate by the fermentation of a gas substrate comprising at least one of CO and a mixture of CO 2 with hydrogen using a homoacetogenic microorganism to convert the gas stream to the product, the method comprising:

a. passing the gas substrate stream to a fermentation zone containing an anaerobic microorganism and a fermentation liquid;

b. converting the gas substrate stream to the product by contact of the anaerobic microorganism in the fermentation zone with the gas substrate stream;

c. providing at least one crotonate-like compound to the fermentation liquid in an amount sufficient to inhibit a production of butyrate and/or butanol by butyryl-CoA dehydrogenase by at least one species of microorganism in the fermentation zone, said crotonate-like compound represented by the structural formula

R 2 (R 3 )C═C(H)C(O)R 1   I.

or

R 2 -A-C(O)R 1   II.

wherein:

R 1 is —OH, —OR 5 , or —N(R 4 ) 2 , wherein R 5 is hydrocarbyl and each R 4 may be the same or different and is hydrogen or hydrocarbyl;

R 2 is hydrogen, —NH 2 , —OH or —CX 3 wherein each X may be the same or different and is hydrogen or halogen;

R 3 is hydrocarbyl of 1 to 18 carbons which may be unsubstituted or substituted with —OH, alkoxyl of 1 to about 6 carbons, or halogen;

A is an aromatic moiety having 5 or 6 ring atoms which may be all carbon atoms or may be heterocyclic with one hetero atom selected from the group consisting of oxygen and nitrogen which aromatic moiety has —R 2 at the 2 position wherein —R 2 is as defined above and which aromatic moiety may be unsubstituted or substituted at one or more of the higher carbon positions with (i) hydrocarbyl of 1 to 18 carbons which may be substituted with —OH, alkoxyl of 1 to about 6 carbons, or halogen, (ii) —OR 6 wherein R 6 is lower alkyl, (iii) —N(R 7 ) 2 wherein each R 7 is the same or different and is hydrogen or hydrocarbyl or (iv) halogen;

with the proviso that in structural formula I, at least one of R 2 and R 3 is or is substituted with haloalkyl and that in formula II at least the 2 or 3 carbon position of the aryl moiety is substituted with an electron withdrawing group selected from the group consisting of halogen and haloalkyl;

d. withdrawing the product containing fermentation liquid from the fermentation zone; and

e. recovering the product from the fermentation liquid.

19. The method of claim 18 wherein the crotonate-like compound is represented by the formula:

R 2 (R 3 )C═C(H)C(O)R 1   III.

or

R 2 -A-C(O)R 1   IV.

wherein:

in formula III, R 2 is —OH, —NH 2 or —CX 3 wherein X is fluorine, and R 3 is —CX 3 wherein X is fluorine, and

in formula IV, the aryl is phenyl and at least one of the 2 and 3 position carbons of the phenyl moiety is —CX 3 wherein X is fluorine.