(62e) Production of Bio-Fuels From Giant Miscanthus

The energy crop giant miscanthus was pyrolyzed in a laboratory-scale auger reactor at Mississippi State University (MSU). The influence of pyrolysis temperature and biomass pyrolysis time on bio-oil yields is investigated. Pyrolysis temperature of giant miscanthus was varied between 375-450 °C. The highest bio-oil yield of 60 wt% was obtained at 425 °C. Best yield was also a function of biomass feed rate during pyrolysis. We found that maximum yield was attained for an approximate doubling of feedstock feed rate for giant miscanthus as compared to that for pine wood. The reason for this is likely due to differences in particle thickness with wood particles having approximately double or more the thickness of pine wood particles. This apparently allowed the giant miscanthus feedstock particles to pyrolyzed fully at a higher rate. When fed at a the same rate as for pine particles over pyrolysis of the miscanthus occurred as evidenced by lower yields and higher water content of the resulting bio-oil.

Further, raw bio-oil from giant miscanthus in the presence of hydrotreating/hydrocracking catalyst with high temperature and high hydrogen pressure yields hydrocarbons and water. MSU has developed effective hydrotreating (HT) and hydrocracking (HC) catalysts that have successfully produced a hydrocarbon mixture from pine-based bio-oil. These catalysts were applied to the hydroprocessing of giant miscanthus bio-oil. Giant miscanthus bio-oil demonstrated some differences in response to the first-stage HT and second-stage HC treatments as compared to pine bio-oil. These differences will be described in our paper. The physical and chemical properties of giant miscanthus bio-oil and upgraded bio-oil are determined. The fuel-value characteristics of the hydrocarbons produced by two-stage HT and HC will be fully described by analysis by GC/MS and FTIR. Simulated distillation will be performed on the hydrocarbons to describe the boiling range distribution of the hydrocarbon weights produced with comparison of these weights to those of petroleum fuels in the same molecular weight classes.