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]
There are several microorganisms, which can produce fuels and chemicals by syngas utilization. These microorganisms are mostly known as acetogens including Clostridium ljungdahlii,[4] Clostridium autoethanogenum,[5] Eurobacterium limosum,[6] Clostridium carboxidivorans P7,[7] Peptostreptococcus products,[8] and Butyribacterium methylotrophicum.[9]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:
- Gas-liquid mass transfer limitation[9]
- Low volumetric productivity
- Inhibition of organisms.[1][2]
References
- 1 2 (Brown, 2003)
- 1 2 3 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
- ↑ Abubackar, H.N.; Veiga, M. C.; Kennes, C. (2011). "Biological conversion of carbon monoxide: rich syngas or waste gases to bioethanol". Biofuels, Bioproduct &. Biorefineries 5 (1): 93–114. doi:10.1002/bbb.256.
- ↑ 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.
- ↑ 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.
- ↑ 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 Eurobacterium limosum KIST612". Process Biochemistry 37 (4): 411–421. doi:10.1016/S0032-9592(01)00227-8.
- ↑ 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.
- ↑ 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. PMC 178064. PMID 8655492.
- 1 2 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.
Books
- Brown, Robert C. (2003). Biorenewable resources: engineering new products from agriculture. Ames, Iowa: Iowa State Press. ISBN 0-8138-2263-7.