M44
Catalytic Oxidative Pretreatment of Woody Biomass At Mild Reaction Conditions and Enzymatic Conversion to Fermentable Hydrolysate
Monday, April 28, 2014
Exhibit/Poster Hall, lower level (Hilton Clearwater Beach)
Zhenglun Li1, Namita Bansal2, Yaoping Zhang3, Trey K. Sato3, Charles H. Chen4, Li Hinchman3, Ramin Vismeh5, Alexander Toulokhonov6, Eric L. Hegg6 and David B. Hodge7, (1)Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI, (2)Biochemistry, Michigan State University, East Lansing, MI, (3)DOE Great Lakes Bioenergy Research Center, University of Wisconsin, Madison, WI, (4)Chemical Engineering and Materials Science, Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI, (5)Chemistry, and DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI, (6)Biochemistry and Molecular Biology, Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI, (7)DOE Great Lakes Bioenergy Research Center, Michigan State University, East Lansing, MI
We previously developed the alkaline peroxide pretreatment catalyzed by copper-diimine complexes, which significantly increases the enzymatic digestibility of a range of herbaceous and woody feedstocks including switchgrass, prairie cordgrass as well as hybrid poplar. Under mild operation conditions (room temperature and ambient pressure), the maximum efficacy of the pretreatment can be achieved with less than one hour of reaction time. Mechanistic studies of the catalytic oxidation reveal disruption of cell wall layers, which is associated with lignin removal and cellulose oxidation. We optimized the key parameters during pretreatment and enzymatic hydrolysis, which produces hydrolysate from recalcitrant hammer-milled hybrid poplar with >80% yield of monomeric sugars.
Fermentation studies indicate that the hydrolysate from hybrid poplar can easily be fermented to ethanol, regardless of the toxicity from the residual copper catalyst in the hydrolysate. The severity of the toxicity can be alleviated by a simple process of catalyst recovery prior to fermentation, or by using lower amount of an improved less-toxic catalyst during pretreatment. LCMS analysis of the hybrid poplar hydrolysate has demonstrated the presence of monomeric lignin fragments including vanillin, syringic acid and p-hydroxybenzoic acid, which as aromatic by-products add to the overall profitability of the biorefinery process. Further investigations of the lignotoxins in the hydrolysate have provided more important information on hydrolysate toxicity as well as valuable guidance for the future optimization of yeast strains.
