Tuesday, April 20, 2010
8-23

Design and use of a fixed bed flowthrough reactor for pretreatment of poplar and birchwood xylan

Heather L. McKenzie, Department of Chemical & Environmental Engineering, Center for Environmental Research and Technology, University of California Riverside & BioEnergy Science Center, 1084 Columbia Ave, Riverside, CA 92507 and Charles E. Wyman, Center for Environmental Research and Technology and Chemical and Environmental Engineering Department, University of California Riverside & BioEnergy Science Center, 1084 Columbia Avenue, Riverside, CA 92521.

High temperature water-only pretreatment can primarily solubilize hemicellulose as oligomers plus lower amounts of monomeric sugars and greatly enhance the susceptibility of the cellulose remaining in the solids to enzymatic hydrolysis.  The current understanding of hemicellulose hydrolysis does not address substrate complexity or the effects of xylooligomers, lignin, and the interaction of biomass components on performance.  Furthermore, pretreatment is frequently conducted in batch reactors which can make the collection of time-dependent data difficult.  A fixed bed flowthrough reactor facilitates tracking the release of hemicellulose components as a function of time, thus making it a valuable laboratory tool for studying deconstruction fundamentals and developing kinetic models.  A flowthrough reactor heated using a fluidized sand bath has been employed in the UCR laboratory for some time, and a steam jacketed flowthrough reactor is being constructed to take advantage of the superior properties of steam as a heating medium.  The void volume and flow behavior in the reactors will be determined to characterize mass transfer in the system, and reactor conditions (reaction time, temperature, and flow rate) will be optimized to track the release of xylose, xylooligomers, xylose degradation products, and lignin from poplar and compared to data for birchwood xylan.  Understanding the flow behavior and release patterns of these compounds will improve the understanding of the relative importance of mass transfer and kinetics in pretreatment.  Comparison of results with poplar and xylan should also help clarify the interaction of xylan with the other compounds in poplar such as cellulose and lignin.