Syngas fermentation

Syngas fermentation, also known as synthesis gas fermentation, is a microbial process. In this process, a mixture of hydrogen, carbon monoxide, and carbon dioxide, known as syngas, is used as carbon and energy sources, and then converted into fuel and chemicals by microorganisms.[1]

The main products of syngas fermentation include ethanol, butanol, acetic acid, butyric acid, and methane.[2] Certain industrial processes, such as petroleum refining, steel milling, and methods for producing carbon black, coke, ammonia, and methanol, discharge enormous amounts of waste gases containing mainly CO and H
2 into the atmosphere either directly or through combustion. Biocatalysts can be exploited to convert these waste gases to chemicals and fuels as, for example, ethanol.[3] In addition, incorporating nanoparticles has been demonstrated to improve gas-liquid fluid transfer during syngas fermentation. [4]

There are several microorganisms which can produce fuels and chemicals by syngas utilization. These microorganisms are mostly known as acetogens including Clostridium ljungdahlii,[5] Clostridium autoethanogenum,[6] Eubacterium limosum,[7] Clostridium carboxidivorans P7,[8] Peptostreptococcus productus,[9] and Butyribacterium methylotrophicum.[10] Most use the Wood–Ljungdahl pathway.

Syngas fermentation process has advantages over a chemical process since it takes places at lower temperature and pressure, has higher reaction specificity, tolerates higher amounts of sulfur compounds, and does not require a specific ratio of CO to H
2.[2] On the other hand, syngas fermentation has limitations such as:

Reactor types

The most common utilized reactor type for syngas fermentation is the stirred-tank reactor in which the mass transfer is influenced by several factors such as geometry of the reactor, impeller configuration, the agitation speed and the gas flow rate. Additionally, less investigated reactor types like Trickle-bed reactors, bubble-column reactors and gas-lift reactors have specific drawbacks and advantages regarding the abovementioned limitations.[11]


References

  1. ^ a b Brown, Robert C. (2003). Biorenewable resources: engineering new products from agriculture. Ames, Iowa: Iowa State Press. ISBN 0-8138-2263-7.
  2. ^ a b c Worden, R.M., Bredwell, M.D., and Grethlein, A.J. (1997). Engineering issues in synthesis gas fermentations, Fuels and Chemicals from Biomass. Washington, DC: American Chemical Society, 321-335
  3. ^ Abubackar, H.N.; Veiga, M. C.; Kennes, C. (2011). "Biological conversion of carbon monoxide: rich syngas or waste gases to bioethanol" (PDF). Biofuels, Bioproducts and Biorefining. 5 (1): 93–114. doi:10.1002/bbb.256. hdl:2183/13730. S2CID 84912109.
  4. ^ Sajeev, Evelyn; Shekher, Sheshank; Ogbaga, Chukwuma C.; Desongu, Kwaghtaver S.; Gunes, Burcu; Okolie, Jude A. (June 2023). "Application of Nanoparticles in Bioreactors to Enhance Mass Transfer during Syngas Fermentation". Encyclopedia. 3 (2): 387–395. doi:10.3390/encyclopedia3020025.
  5. ^ Klasson, K.T.; Ackerson, M. D.; Clausen, E. C.; Gaddy, J.L. (1992). "Bioconversion of synthesis gas into liquid or gaseous fuels". Enzyme and Microbial Technology. 14 (8): 602–608. doi:10.1016/0141-0229(92)90033-K.
  6. ^ Abrini, J.; Naveau, H.; Nyns, E.J. (1994). "Clostridium autoethanogenum, sp. nov., an anaerobic bacterium that produces ethanol from carbon monoxide". Archives of Microbiology. 161 (4): 345–351. doi:10.1007/BF00303591. S2CID 206774310.
  7. ^ Chang, I. S.; Kim, B. H.; Lovitt, R. W.; Bang, J. S. (2001). "Effect of CO partial pressure on cell-recycled continuous CO fermentation by Eubacterium limosum KIST612". Process Biochemistry. 37 (4): 411–421. doi:10.1016/S0032-9592(01)00227-8.
  8. ^ Ahmed, A; Lewis, R.S. (2007). "Fermentation of biomass generated syngas:Effect of nitric oxide". Biotechnology and Bioengineering. 97 (5): 1080–1086. doi:10.1002/bit.21305. PMID 17171719. S2CID 21650852.
  9. ^ Misoph, M.; Drake, H.L. (1996). "Effect of CO2 on the fermentation capacities of the acetogen Peptostreptococcus productus U-1". Journal of Bacteriology. 178 (11): 3140–3145. doi:10.1128/jb.178.11.3140-3145.1996. PMC 178064. PMID 8655492.
  10. ^ a b Henstra, A.M.; Sipma, J.; Reinzma, A.; Stams, A.J.M. (2007). "Microbiology of synthesis gas fermentation for biofuel production". Current Opinion in Biotechnology. 18 (3): 200–206. doi:10.1016/j.copbio.2007.03.008. PMID 17399976.
  11. ^ Grimalt‐Alemany, Antonio; Skiadas, Ioannis V.; Gavala, Hariklia N. (January 2018). "Syngas biomethanation: state‐of‐the‐art review and perspectives". Biofuels, Bioproducts and Biorefining. 12 (1): 139–158. doi:10.1002/bbb.1826.