Catalytic Conversion of Biomass to Bio-Fuels

The conversion of biomass to biouel has received considerable attention as a sustainable way to produce energy. As worldwide fossil fuels become depleted these efforts grow in importance. The overall strategy is to transform the parent biomass feedstock to increase C-C bonds while reducing oxygen in the final products. A catalytic approach is often used to achieve good yields of transportation grade liquid hydrocarbons from biomass. Development of novel catalyst systems to aid in the thermochemical conversion of biomass to biouel is the focus of this thesis. Gasification of biomass produces synthesis gas (CO and H2). Synthesis gas can be converted to liquid hydrocarbons using Fischer-Tropsch (FT) synthesis. Mo/ZSM-5 FT catalysts with a potassium (K) promoter are introduced to enhance liquid hydrocarbon production and CO conversion of synthesis gas. Liquid products and CO conversion were determined using GC-MS analysis with respect to changes in K loading from 0-2%. The highest liquid product selectivity (21.7%) was found with 1.0% K loading while largest CO conversion (63%) was found with 1.2% K loading. This catalyst work was extended by introducing Ni and Co into the Mo/ZSM-5 catalysts. A copper based water gas shift catalyst (WGS) was also used in concert with the FT catalyst to improve product selectivity. This WGS catalyst promotes the in-situ production of H2 while decreasing water content. The FT+WGS catalyst were used to convert both 1:1 CO: H2 syngas and bio-syngas at 280 °C and 350 °C. The liquid hydrocarbon selectivity was significantly changed and the CO conversion was remarkably increased compared to the reactions without the dual catalyst at both temperatures. In the fourth chapter, FT+WGS catalysts were studied for upgrading bio-oil model compounds. Guaiacol and furfural were used as the model compounds and upgrading reactions were done under H2, syngas and bio-syngas at 200, 250 and 300 °C. Significant conversion of both guaiacol (85%) and furfural (100%) occurred with syngas at 300 °C. Products upgraded from syngas had a higher combined heat of combustion than the products with pure H2. This suggests the incorporation of some C from CO with model compound upgrading reactions with syngas