ABSTRACT
100The last few decades have witnessed dramatic improvements made in the production of fuels and chemicals from biomass and fermentation derived butanol production from corn is no exception. The art of producing butanol from corn that existed during World Wars I and II is no longer seen as an art but rather as science. Recent developments have brought, once again, the forgotten acetone butanol ethanol (ABE) fermentation from corn closer to commercialization. Superior strains have been developed, along with state-of-the-art upstream, downstream, and fermentation technologies. Butanol can be produced not only from corn starch as was done decades ago, but also from corn coproducts such as corn fiber and corn steep liquor (CSL) as a nutrient supplement. These additional substrates add to the improved yield and superior economics of the butanol process. Downstream processing technologies have enabled the use of concentrated sugar solutions to be fermented, thereby resulting in improved process efficiencies. Application of fed-batch fermentation in combination with in situ/inline product recovery by gas stripping and pervaporation is seen as a superior technology for scale-up of butanol production. Similarly, continuous fermentations (immobilized cell and cell recycle) have resulted in dramatic improvement in reactor productivities. This chapter details all the above developments that have been made for production of butanol from corn. As of today, butanol production from corn is competitive with petrochemically produced butanol.
