Fast pyrolysis is a thermochemical approach for biomass liquefaction in which biomass is heated without oxygen to produce pyrolysis gas and char. The majority of the pyrolysis gas can be condensed to bio-oil with a bulk density greater than the feedstock biomass. Deployment of fast pyrolysis near the source of harvest will increase bulk density and reduce the cost of transportation prior to upgrading in a central refinery. However, bio-oil corrosiveness and reactive instability pose significant barriers to the adoption of pyrolysis systems. Catalytic stabilization is needed to produce an energy dense fuel intermediate that is compatible with common infrastructure materials such as carbon steel. Several catalysis approaches, including hydrotreatment and catalytic cracking, are being considered to stabilize and upgrade bio-oil. However, these approaches face high cost, catalyst deactivation and the high cost of producing molecular hydrogen in the regional biomass processing depots. In this context, electrocatalytic hydrogenation (ECH) is proposed to stabilize bio-oil by hydrogenation with in situ atomic hydrogen created by reducing protons in the electrolyte solution. Instead of fossil-based electricity, solar or wind energy can be employed to supply the reducing equivalent. The energy contents of the liquid products are enhanced by addition of solar or wind reducing equivalent. Moreover, this method allows bio-oil stabilization at very mild conditions (25-100°C, 1atm), with little to no evidence of catalyst deactivation.In this dissertation, a 1 Kg/hr screw-conveyor fast pyrolysis reactor was designed and operated to produce bio-oil from poplar biomass. Bio-oil from this reactor was characterized by GC/MS, HPLC, size exclusion chromatography, proximate analysis and ultimate analysis. Bio-oil stability was also studied by performing an accelerated aging test at 80°C. Stabilization of the bio-oil was then investigated using electrocatalytic hydrogenation. The transformation of a bio-oil model compound, furfural, was studied using a nickel sacrificial anode in an undivided cell. Product yields and electrochemical efficiency as functions of electrode type, pH, reactant concentration and current density were examined. To further upgrade the phenolic compounds, a new electrocatalyst, ruthenium supported on activated carbon cloth (Ru/ACC), was invented. The effects of electrode type, electrolyte composition, support property, temperature and current density were investigated. Reaction network was also studied and compared with catalytic hydrodeoxygenation of guaiacol. This catalyst was used to perform electrocatalytic stabilization of water-soluble bio-oil. The majority of the carbonyl groups were hydrogenated to the related alcohols. After the electrocatalytic hydrogenation treatment, bio-oil became more stable compared with the bio-oil without electrocatalytic stabilization. The outcome of this research reveals an advanced understanding of integrated fast pyrolysis and ECH systems for bio-oil stabilization. Pyrolysis followed by electrocatalytic hydrogenation shows significant potential for creating a stable bio-oil that is suitable for further upgrading at central refineries. This integrated approach can help solve the energy deficiency, biomass supply and bio-oil upgrading challenges.
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