(206a) Depolymerization and Catalytic Hydrodeoxygenation of Switchgrass Lignin with Formic Acid As a Hydrogen Source

Second generation biofuels derived from environmentally friendly lignocellulosic crops that do not compete with food crops can potentially be processed into biofuels that can be used to supplement fossil fuels. Approximately a third of lignocellulosic biomass consists of lignin, a high molecular weight polyaromatic macromolecule that consists of units derived primarily from p-hydroxyphenyl (H), guaiacyl (G) and syringyl (S) units. In this study, organosolv lignin isolated from switchgrass was depolymerized and hydrodeoxygenated at 350 °C using a 20 wt% Pt/C catalyst with ethanol solvent in a batch reactor. Formic acid was also utilized in these reactions as a hydrogen source for hydrodeoxygenation. The impact of the Pt catalyst, formic acid and reaction time on liquid products formation was systematically evaluated. The switchgrass lignin was found to produce a wide variety of aromatic compounds, of which 9 compounds were identified and quantified. With increasing reaction time, the H/C ratios were shown to increase while the O/C ratios decreased, thus confirming the progression from raw lignin to“lignin-to-liquid” fuel blends. Additionally, average mixture or bulk properties such as functional group content and thermal stability were studied via NMR and thermogravimetric analysis of the depolymerized mixture, respectively.