(493b) Alkaline Hemicellulose Extraction and Solubility-Based Separation From Hardwoods

Authors: 
Stoklosa, R. J., Michigan State University
Hodge, D., Michigan State University


Woody biomass presents a unique opportunity for the production of liquid biofuels and other chemicals from renewable resources. By utilizing woody biomass, existing supply chains and infrastructure developed for the forest products industry can be employed which both shortens the timeline for commercialization for these technologies and greatly enhances the economic attractiveness of pretreatment technologies that can successfully work on these feedstocks. The challenge is to integrate existing alkaline pulping processes with extraction processes that utilize the hemicellulose and lignin fractions for fermentation or catalyst-derived transportation fuels, solid fuels, and chemicals. An alkaline pre-extraction before pulping or black liquor removal during pulping can permit use of the hemicellulose and lignin fractions for higher value fuels and chemicals. For this work, alkaline extractions will include variations in NaOH loading, time and temperature, and biomass source. The biomass feedstocks will include 3 hardwoods: sugar maple (Acer saccharum) and hybrid poplars (Populus tremuloides x tremula, P. nigra x maximowiczii NM6). Extracted and solubilized hemicelluloses and lignins exhibit different functionalities due to their chemical alteration from the original biopolymer and this work will better characterize the impacts of the extraction conditions on the properties of the solubilized biopolymers and the potential for solubility-based separations to recover hemicellulose and lignin fractions using precipitation by acid and organic solvents. The properties of the total solubilized material and precipitates as a function of extraction condition will be characterized in terms of overall composition, hemicellulose and lignin molecular weight distributions by size exclusion chromatography and a novel assay for xylan degree of polymerization estimation, the degree of substitution of xylan polymers with 4-O-methyl glucuronic acid and acetate, and hemicellulose-lignin aggregation.

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