Optimization of biomass fast pyrolysis for the production of monomers

Fast pyrolysis is a promising method for producing advanced biofuels and chemicals from lignocellulosic biomass. The process will however require further optimization to produce fuels and chemicals at a price competitive to conventional fossil fuel-derived products. Research in this dissertation focuses on both preand postprocesses for optimizing fast pyrolysis to produce increased yields of valuable anhydrosugars and phenolic monomers. The concept of alkali and alkaline earth metal (AAEM) passivation using sulfuric acid had only previously been demonstrated in batch micropyrolyzer trials. A benchscale, continuous-flow auger pyrolyzer was used in this work to demonstrate AAEM passivation on both woody and herbaceous feedstocks. Passivation of AAEMs in red oak and switchgrass increased total sugars by more than 105% and 260%, respectively. Light oxygenates simultaneously decreased by nearly 50% from each feedstock. The synchronous increase in sugars and decrease in light oxygenates provides evidence of the hypothesis that AAEM passivation prevents pyranose ring fragmentation and promotes glycosidic bond cleavage in holocellulose. An undesirable consequence of AAEM passivation was an increase in biochar from both lignin and carbohydrates. Demonstration of the enhanced production of sugars from AAEM passivated feedstocks in a continuous auger pyrolyzer at the kilogram scale is an important step in determining the feasibility of using fast pyrolysis to produce sugars from lignocellulosic biomass.