The production of liquid fuels and chemicals from biomass is an important part of a renewable energy future, and integration of biomass-derived pyrolysis oil into a standard refinery is a potential first step in the integration of renewable feedstocks with existing infrastructure. Currently biomass-derived pyrolysis oil exhibits significant differences from standard petroleum, especially in its characteristic high oxygen content. Standard refinery technology, conversely, is geared towards low-oxygen fuels, and thus no infrastructure exists for the deoxygenation of the refinery input stream, warranting the development of deoxygenation technologies. One promising method is catalytic hydrodeoxygenation of biomass-derived pyrolysis oil. Known catalysts for this process require high hydrogen pressures to saturate the carbon-carbon double bonds prior to deoxygenation, but recent experimental work in this area suggests that direct deoxygenation without saturating double bonds is possible at low hydrogen pressure and high temperature over metal phosphide catalysts. To understand these catalysts, a model of the guaiacol hydrodeoxygenation mechanism over the 001 facet of the Ni2P surface was constructed. The proposed mechanism was determined by first calculating an energy diagram of the possible intermediates and then selecting likely intermediates to form the reaction coordinate. The resulting potential energy surface contains steps that are overall exothermic relative to the separated reactants. As it is clear from the experimental conditions that the hydrogen pressure is an important variable in product selectivity the hydrogen coverage of the Ni?2P(001) surface is determined under catalytic conditions. The deoxygenation mechanism is then proposed and compared to experimental data. Overall, these results indicate a possible direct deoxygenation pathway for guaiacol.

Catalytic upgrading of biomass: Aromatic hydrodeoxygenation over metal phosphide surfaces

248th National Meeting (2014)

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