One of the barriers to fully utilizing the lignin fraction of biomass is its high oxygen content.  Many of the constituents of this fraction consist of aromatic species decorated with oxygen functional groups. This high oxygen content of biomass-derived oil is a significant difference from petroleum-based oil. Much of the current technology for refining oil is constructed towards low-oxygen fuels and thus no infrastructure exits for the deoxygenation of the refinery input stream. In order to solve this problem basic research into the efficient catalytic upgrading of these constituents via deoxygenation is critical. Previous experimental work in this area indicates that the deoxygenation may occur at low hydrogen pressure and high temperature over both noble metal and metal phosphide catalysts. In order to improve these catalysts we have created a model of biomass deoxygenation using the model compound guaiacol over the Pt(111) surface. This proposed mechanism was constructed by first calculating an energy diagram of the possible intermediates and then selecting possible intermediates to form the reaction coordinate. The resulting potential energy surface contains steps that are overall exothermic relative to the separated reactants. These results indicate the possibility of direct deoxygenation of guaiacol could be accomplished under low hydrogen pressure. This is in stark contrast to previous results that indicate that the aromatic ring must be hydrogenated at higher pressures and hydrogen consumption before the removal of oxygenated groups. This model is the starting point for computational catalyst design to optimize the activity or selectivity of biomass deoxygenation catalysts resulting in candidates for experimental verification.

Understanding the mechanism of guaiacol deoxygenation over Pt(111) using DFT calculations

248th National Meeting (2014)

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