(610a) Separation and Purification of Biobutanol During Bioconversion of Biomass

Biofuels from biomass becomes more and more important, due to the limited availability and increasing costs of fossil fuels, the need for reduction in GHG emissions, and energy independence. ABE (Acetone-Butanol-Ethanol) fermentation is the second largest industrial fermentation process after ethanol. Butanol has several advantages over ethanol as a drop-in bio-fuel such as higher energy content, lower vapor pressure, and lower hygroscopy, and it can be produced from non-food, renewable lignocellulosic feedstocks and can be used in existing transportation fuel distribution infrastructure. Thus, biobutanol has the potential to substitute both bioethanol and biodiesel in the biofuels market estimated to be worth $247 billion by 2020. Today, biobutanol can compete with synthetic butanol in the chemicals market (Green 2011).

“Biotanol” can be produced by ABE fermentation using Clostridium acetobutylicum or C. beijerinckii under anaerobic conditions (Kraemer et al., 2010). Current commercial biotanol processes are based on fermentation of starch or sugar-based feedstocks. These feedstocks, however, are usually expensive leading to high production cost. In addition, most biobutanol plants use corn, which may compete with food and feed. Thus, there has been a growing research interest in developing non-food, renewable biomass based drop-in biofuels such as biobutanol. However, there are still many challenges to be solved for making biomass based biobutanol economically and commercially viable. The unsolved challenges include (i) high product (especially butanol) inhibition, (ii) low butanol yield and productivity, and (iii) expensive downstream processing (product separation) (Kraemer et al., 2010; Kumar and Gayen, 2011). Among these challenges, the separation and removal of product butanol is a critical issue. In this study, an extensive review of separation and purification of butanol from fermentation broth is provided, including gas stripping, distillation, liquid-liquid extraction, membrane separation (e.g., pervaporation), adsorption (e.g.., molecular sieve adsorption), membrane solvent extraction, and integrated separation-fermentation, etc. This could be helpful in research and development of renewable butanol biofuels.

References

Green E. M., Fermentative production of butanol – the industrial perspective, Current Opinion of Biotechnology, 22: 1-7 (2011).

Kraemer K., Harwardt A., Bronneberg B., and Marquardt W. Separation of butanol from acetone-butanol-ethanol fermentation by a hybrid extraction-distillation process. 20th European Symposium on Computer Aided Process Engineering – ESCAPE20, S. Pierucci and G. Buzzi Ferraris (Ed.), 2010.