In recent years, growing attention has been devoted to the use of lignocellulosic biomass as a feedstock to produce renewable carbohydrates as a source of energy products, including liquid alternatives to fossil fuels. Currently, research is driven by the need to reduce the cost of biomass-ethanol production. One of the preferred methods is to thermochemically pretreat the biomass material and subsequently, enzymatically hydrolyze the pretreated material to fermentable sugars that can then be converted to ethanol using specialized microorganisms. The main goal of pretreatment is enhance enzymatic conversion of the cellulose fraction, and, hopefully, obtain a higher ethanol yield. Most previous studies on biomass pretreatment have involved pure species, but mixtures of biomass are likely to be feedstocks for agricultural and forest biorefineries. The primary goal of this research is to obtain kinetic detailed data for dilute acid hydrolysis from mixtures of several timber species from the Upper Midwest region of the United States and switchgrass. These results will be used to identify optimum reaction conditions to maximize production of fermentable sugars and minimize production of non-fermentable byproducts.

Dilute acid-catalyzed hydrolysis of biomass, including aspen, basswood, balsam, red maple, and switchgrass, will be studied at various temperatures, acid concentrations, and particle sizes in a 1-L well-mixed batch reactor (Parr Instruments, Model 4570). 25g of biomass and 500mL of diluted acid solution will be added into a 1-L glass liner, and then put into the reactor. During the experiment, 5 ml samples are then taken starting at 130oC at 3 min intervals until reaching the temperature setpoint (160, 175, or 190oC), followed by 4 samples after achieving the setpoint temperature. The collected samples will then be cooled in an ice bath to stop the reaction. The cooled samples will be filtered using 0.2 mm MILLIPORE membrane filter to remove suspended solids. The filtered samples were then analyzed using High Performance Liquid Chromatography (HPLC) with a Bio-Rad Aminex HPX-87P column, and refractive index detection to measure monomeric and polymeric sugars plus degradation byproducts. A first order reaction model will be assumed and the kinetic parameters such as activation energy and pre-exponential constant were obtained from a match between the model and data.

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