(546e) Corn Stover Deconstruction Using Ionic Liquid – Glycerol Mixtures

Intertwined cellulose, hemicelluloses, and lignin biomacromolecules make up the recalcitrant structure of lignocellulosic biomass. The configuration of this kind of biomass makes deconstruction to its components challenging. Yet the prospect of using biomass, particularly agricultural residues, for renewable energy or for sustainable chemicals is inviting. Corn stover, in particular, is available in the US Midwest in quantities estimated to be greater than 30 million metric tons/year.

Certain ionic liquids (ILs), salts that are molten below 100 °C, can preferentially dissolve lignocellulosic biomass fractions. The ILs studied in this work were 1-ethyl-3-methylimidazolium acetate and 1-ethyl-3-methylimidazolium formate. Though they are effective, do not produce hazardous emissions, and are recyclable, these ILs are costly. To reduce solvent expense, we examined diluting them with non-hazardous compounds. We found that glycerol, a low-value by-product of the growing biodiesel industry, is fully miscible with the selected ILs, and is a potentially useful co-solvent. Solvent mixtures, produced from 50% or 75% glycerol with the remainder being one of the selected ILs, were used to pretreat corn stover. Dilution of the ILs with up to 75% glycerol was found to enhance the glucose and xylose yields after enzymatic hydrolysis, compared to raw corn stover or corn stover treated with pure IL. FTIR spectra of the raw and pretreated corn stover suggests that lignin had been dissolved into the IL- glycerol mixture and that some of the crystalline cellulose had been converted to amorphous cellulose, which is more easily hydrolyzed.