Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/27/2003
Publication Date: 3/27/2003
Citation: Mosier, N., Hendrickson, R., Dreschel, R., Dien, B.S., Bothast, R.J., Welch, G., Ladisch, M.R. 2003. Principles and economics of pretreating cellulose in water for ethanol production [abstract]. American Chemical Society. Paper No. 103.
Technical Abstract: The aqueous pretreatment of corn fiber and corn stover at a pH controlled to minimize the hydrolysis of oligosaccharides and formation of monosaccharides during pretreatment has been studied at the laboratory scale, and in the case of corn fiber, in an operational ethanol plant. For corn fiber, the pretreatment process consists of mixing fiber with stillage and pumping the mixture through a heat exchanger and past a steam injector to heat it to 160 deg C. The material is held at this temperature for 20 minutes as it is pumped through a coil whose length determines the residence time. The fiber then passes through a centrifuge where liquid containing dissolved oligosaccharides is separated from the remaining solids. Enzymes are added to the liquid (or in some cases to the pretreated slurry, itself) to hydrolyze the glucans and/or pentosans to yield sugars that are fermented to ethanol using yeast. For corn stover, water would be used in place of stillage, and the pretreatment temperature is 190 deg C. Experimental results in the laboratory and the plant show that this approach to pretreatment enhances cellulose conversion while avoiding the formation of fermentation inhibitors. Tests at the Williams facility, carried out with a fiber/stillage mixture containing 9.5% suspended solids and 8.7% dissolved solids, showed the pretreated streams were readily fermented to ethanol by yeast. The technical principles of this pretreatment process and an analysis of its economics in the context of an existing ethanol production facility will be presented.