Solving our nation’s energy problems is of highest priority as developing a source of sustainable domestic energy would improve the energy security and independence of the U.S. and also positively impact the environment and the economy. The transportation sector poses a large challenge to sustainable energy development due to the high energy density fuel required, making liquid fuels favorable over fuel cells or electricity. Development of liquid transportation fuels from biomass provides a solution to creating a sustainable alternative to replace liquid fossil fuels. The H2Bioil (1) process, involving high pressure catalytic fast-hydropyrolysis of biomass followed by a second stage fixed-bed hydrodeoxygenation (HDO) reactor, has been proposed to generate transportation fuels from lignocellulosic biomass. During fast-pyrolysis, hundreds of vapor compounds are generated and, if condensed, would produce a bio-oil with high oxygen content (~35-40 wt %) and an energy content this is half that of gasoline (~17 MJ/kg). Therefore, the vapors must be upgraded, via catalytic hydrodeoxygenation, to increase the energy content, reduce oxygen content to within 3-5%, and increase pH and oil stability.
This presentation will focus on the catalytic hydrodeoxygenation aspect of the proposed process. Due to the large number of vapor compounds produced during fast-pyrolysis and the variety of oxygen functional groups they contain, model compound studies present a method for gaining fundamental understanding of the link between catalyst functionality and oxygen functional group. The lignin portion of biomass poses the greatest challenge in upgrading and conversion to transportation fuels, and therefore lignin derived model compounds were the focus of this study. Supported metal catalysts, such as Ru, have shown desirable hydrodeoxygenation activity of lignin model compounds containing phenol and methoxy oxygen functional groups at 350-800psi in hydrogen and 300-450oC without hydrogenating the aromatic ring.
1) R. Agrawal, N. R. Singh, Synergistic Routes to Liquid Fuel for a Petroleum Deprived Future, AIChE Journal,55,7,1898-1905, 2009.