Process for controlling sulfur in a fermentation syngas feed stream

• US 8,597,934 B2
• Filed: 10/28/2010
• Issued: 12/03/2013
• Est. Priority Date: 10/30/2009
• Status: Expired due to Fees

• Current Assignee: Synata Bio, Inc.
• Original Assignee: Coskata, Inc.
• Inventors: Tobey, Richard E.
• Primary Examiner(s): Tate, Chris R
• Assistant Examiner(s): White, Douglas F
• Application Number:
  US12/914,632
• Publication Number:
  US 20110104770A1
• Time in Patent Office: 1,132 Days
• Field of Search: None
• US Class Current: 435/266
• CPC Class Codes: C10J 2300/0906 Physical processes, e.g. shredding, comminuting, chopping, sorting
• CPC Class Codes: C10J 2300/0909 Drying
• CPC Class Codes: C10J 2300/0916 Biomass
• CPC Class Codes: C10J 2300/092 Wood, cellulose
• CPC Class Codes: C10J 2300/0983 Additives
• CPC Class Codes: C10J 2300/0996 Calcium-containing inorganic materials, e.g. lime
• CPC Class Codes: C10J 2300/1238 by plasma
• CPC Class Codes: C10J 2300/1656 Conversion of synthesis gas to chemicals
• CPC Class Codes: C10J 2300/1665 to alcohols, e.g. methanol or ethanol preparation of alcohols in general C07C29/00
• CPC Class Codes: C10J 2300/1681 with biological plants, e.g. involving bacteria, algae, fungi
• CPC Class Codes: C10J 2300/1884 with one stream being synthesis gas
• CPC Class Codes: C10J 2300/1892 with one stream being water/steam
• CPC Class Codes: C10J 3/08 with ash-removal in liquid state
• CPC Class Codes: C10J 3/18 using electricity
• CPC Class Codes: C10J 3/723 Controlling or regulating the gasification process
• CPC Class Codes: C10K 1/004 Sulfur containing contaminants, e.g. hydrogen sulfide
• CPC Class Codes: C10K 1/02 Dust removal
• CPC Class Codes: C10K 1/06 combined with spraying with water C10K1/001 takes precedence
• CPC Class Codes: C12P 7/04 acyclic
• CPC Class Codes: C12P 7/065 with microorganisms other than yeasts
• CPC Class Codes: C12P 7/08 : produced as by-product or from waste or cellulosic material substrate
• CPC Class Codes: C12P 7/10 : substrate containing cellulosic material
• CPC Class Codes: C12P 7/16 : Butanols
• CPC Class Codes: C12P 7/52 : Propionic acid; Butyric acids
• CPC Class Codes: C12P 7/54 : Acetic acid vinegar C12J
• CPC Class Codes: Y02E 50/10 : Biofuels, e.g. bio-diesel
• CPC Class Codes: Y02E 50/30 : Fuel from waste, e.g. synthetic alcohol or diesel
• CPC Class Codes: Y02P 20/145 : the feedstock being materials of biological origin

Abstract

Ethanol and other liquid products are produced from biomass using gasification of the biomass to produce a syngas containing CO2, CO, H2 and sulfur or sulfur compounds that passes the syngas to a fermentation step for the conversion of the CO and CO2 and H2 to ethanol. Sulfur and sulfur compounds in the syngas are used to satisfy sulfur demanded by bacteria in the fermentation step. A sulfur control additive is added to the gasification to control syngas sulfur and sulfur compounds at a desired concentration to meet bacteria sulfur demand.

Claims

1. A process for producing liquid products from biomass generated syngas using microorganisms having metabolic processes that utilize sulfur in limited amounts, the method comprising:

a) charging a biomass feed containing sulfur compounds to a gasification unit;

b) heating the biomass feed in an oxygen controlled atmosphere within the gasification unit to produce a gasifier residue, gaseous sulfur or sulfur compounds, and syngas containing at least one of CO or a mixture of CO₂ and H₂;

c) adding a sulfur control additive at an adjustable rate to a heated zone of the gasification unit produced by step b) thereby generating a sulfide compound that becomes part of the gasifier residue and reduces the sulfur or sulfur compounds in the syngas, wherein the rate of sulfur control additive addition is adjusted in response to a measured concentration of sulfur in the sulfur containing syngas;

d) removing the gasifier residue from the gasification unit;

e) collecting gaseous sulfur or sulfur compounds with the syngas from the gasification unit to produce sulfur containing syngas and passing at least a portion of the sulfur containing syngas to a bioreactor;

f) contacting the sulfur containing syngas in the bioreactor with microorganisms to convert at least a portion of the syngas components to the liquid products and to provide sulfur to the microorganisms, wherein the microorganisms in the bioreactor comprises a mono-culture or a co-culture of microorganisms requiring anaerobic growth condition and that require a minimum amount of sulfur for their metabolic function and producing liquid products while not exceeding a maximum amount of sulfur that will reduce the microorganisms production of liquid products; and

,

g) recovering a fermentation liquid from the bioreactor containing the liquid products.

2. The process of claim 1, wherein the biomass comprises carbonaceous materials selected from one or more the group consisting of wood, miscanthus, switchgrass, sugar cane bagasse, corn stover, urban waste, and recycled bioreactor waste.

3. The process of claim 1, wherein the gasifier residue is rapidly removed from the gasification unit before sulfur and metals in the gasifier residue evolve back into the syngas.

4. The process of claim 1 wherein the heated zone of the gasification unit operates at a temperature of from 500 to 4000.degree.C.

5. The process of claim 3, wherein the residue from the gasification unit comprises one or more of the group consisting of a molten slag, an agglomerated ash, and a particulate.

6. The process of claim 3, further comprising charging a gasifier residue melting point modifier to the gasification unit.

7. The process of claim 1, further comprising charging steam or water to the gasification unit.

8. The process of claim 1, further comprising recovering heat from at least a portion of sulfur containing syngas from the gasification unit before contacting the syngas with microorganisms in the bioreactor and using the recovered heat to generate steam for at least one of drying the biomass feed or recovering products from the fermentation.

9. The process of claim 1, wherein the adjustable rate for adding the sulfur control additive is adjusted to produce a desired concentration of sulfur contributed to the bioreactor from the sulfur containing syngas that ranges from minus 100 to plus 500 percent of a metabolic sulfur demand of the microorganisms.

10. The process of claim 1, further comprising adding the sulfur control additive to the heated zone of the gasification unit at an adjustable rate.

11. The process of claim 1, wherein the sulfur control additive comprises at least one of the group of oxides, salts, and elemental forms of transition metals.

12. The process of claim 1, wherein the sulfur control additive comprises at least one of the group iron, iron oxide, zinc, zinc oxide, manganese, and manganese oxide.

13. The process of claim 1, wherein the liquid products comprise at least one of ethanol, propanol, propionic acid, acetic acid, butanol, or butyric acid.

14. The process of claim 1 wherein the microorganisms in the bioreactor comprises a mono-culture or a co-culture of at least one of Clostridium ragsdalei, Butyribacterium methylotrophicum, Clostridium ljungdahlii, Clostridium autoethanogenum, Clostridium woodii, Clostridium neopropanologen and Clostridium carboxydivorans.

15. The process of claim 1, further comprising charging an oxygen containing gaseous feed to the gasification unit wherein the oxygen containing gaseous feed is selected form one or more of the group of air, oxygen enriched air, and essentially pure oxygen.

16. The process of claim 14 wherein the fermentation liquid comprises ethanol in a concentration of at least 0.1 wt %.

17. A process for producing liquid products from biomass generated syngas using microorganisms having metabolic processes that utilize sulfur in limited amounts, the method comprising:

a) charging a biomass feed containing sulfur compounds to a gasification unit;

b) heating the biomass feed in an oxygen controlled atmosphere within the gasification unit to produce a molten gasifier residue, gaseous sulfur or sulfur compounds, and syngas containing at least one of CO or a mixture of CO₂ and H₂;

c) adding a sulfur control additive comprising at least one of oxides, salts or elemental forms of transition metals to a heated zone of the gasification unit at an adjustable rate to generate a sulfide compound that melts at the temperature of the gasification and becomes part of the molten gasifier residue to produce a gasifier residue containing sulfur and to lower the concentration of the sulfur or sulfur compounds in the syngas;

d) removing the molten gasifier residue containing sulfur from the gasification unit,wherein the gasifier residue is rapidly removed from the gasification unit before sulfur and metals in the gasifier residue evolve back into the syngas;

e) collecting gaseous sulfur or sulfur compounds with the syngas from the gasification unit to produce sulfur containing syngas and passing at least a portion of the sulfur containing syngas to a bioreactor;

f) contacting the sulfur containing syngas in the bioreactor with microorganisms to convert at least a portion of the syngas components to the liquid products and to provide sulfur to the microorganisms,wherein the microorganisms in the bioreactor comprises a mono-culture or a co-culture of microorganisms requiring anaerobic growth condition and that require a minimum amount of sulfur for their metabolic function and producing liquid products while not exceeding a maximum amount of sulfur that will reduce the microorganisms production of liquid products;

g) measuring a concentration of sulfur in the sulfur containing syngas and adjusting the rate of sulfur control additive addition to the gasification unit in response to a measured concentration of sulfur in the sulfur containing syngas; and

,

h) recovering a fermentation liquid from the bioreactor containing the liquid products.

18. The process of claim 17, wherein the heated zone of the gasifier operates at a temperature of from 500 to 4000.degree. C.

19. The process of claim 17, further comprising charging a gasifier residue melting point modifier to the gasification unit.

20. The process of claim 17, wherein the adjustable rate for adding the sulfur control additive is adjusted to produce a desired concentration of sulfur in the sulfur containing syngas that ranges from minus 100 to plus 500 percent of a metabolic sulfur demand of the microorganisms.

21. The process of claim 17, wherein the liquid products comprise at least one of ethanol, propanol, acetic acid, propionic acid, butanol, or butyric acid.

22. The process of claim 17, wherein the microorganisms in the bioreactor comprises a mono-culture or a co-culture of at least one of Clostridium ragsdalei, Butyribacterium methylotrophicum, Clostridium ljungdahlii, Clostridium autoethanogenum, Clostridium woodii, Clostridium neopropanologen and Clostridium carboxydivorans.

23. The process of claim 17, wherein the fermentation liquid comprises ethanol in a concentration of an at least 0.1 wt %.

24. A process for producing ethanol from biomass generated syngas using microorganisms having metabolic processes that utilize sulfur in limited amounts, the method comprising:

a) charging a biomass feed containing sulfur compounds to a gasification unit;

b) charging an oxygen containing gaseous feed to the gasification unit and heating the biomass feed in an oxygen controlled atmosphere within the gasification unit to produce a molten slag, gaseous sulfur or sulfur compounds, and syngas containing at least one of CO or a mixture of CO₂ and H₂;

c) adding a sulfur control additive comprising at least one of oxides, salts or elemental forms of transition metals at an adjustable rate to a zone of the gasification unit that generates a sulfide compound that melts at the temperature of the gasification and becomes part of the molten slag to produce a slag containing sulfur and to reduce the sulfur or sulfur compounds in the syngas;

d) removing the molten slag containing sulfur from the gasification unit, wherein the molten slag is rapidly removed from the gasification unit before sulfur and metals in the molten slag evolve back into the syngas;

e) collecting gaseous sulfur or sulfur compounds with the syngas from the gasification unit to produce sulfur containing syngas in a concentration that ranges from minus 100 to plus 500 of the metabolic demand of the microorganisms and passing at least a portion of the sulfur containing syngas to a bioreactor;

f) contacting the sulfur containing syngas in the bioreactor with microorganisms to convert at least a portion of the syngas components to the liquid products and to supply sulfur compounds to the microorganisms, wherein the microorganisms in the bioreactor comprises a mono-culture or a co-culture of microorganisms requiring anaerobic growth condition and that require a minimum amount of sulfur for their metabolic function and producing liquid products while not exceeding a maximum amount of sulfur that will reduce the microorganisms production of liquid products;

g) measuring the concentration of sulfur in the sulfur containing syngas and adjusting the rate of sulfur control additive addition to the gasification unit in response to the measured concentration of sulfur in the sulfur containing syngas;

h) recovering a fermentation liquid from the bioreactor containing ethanol in a concentration of at least 0.1 wt %; and

,

i) recovering heat from at least a portion of the sulfur containing syngas upstream of the bioreactor and using the recovered heat to generate steam for at least one of drying the biomass feed or recovering products from the fermentation.

25. The process of claim 24, wherein the microorganisms in the bioreactor comprises a mono-culture or a co-culture of at least one of Clostridium ragsdalei, Butyribacterium methylotrophicum, Clostridium ljungdahlii, Clostridium autoethanogenum, Clostridium woodii, Clostridium neopropanologen and Clostridium carboxydivorans.