Lignin degradation from catalytic fast pyrolysis results in a variety of oxygen functionalized aromatic molecules. The presence of oxygen in these products significantly reduces the quality of the resulting bio-oil and must be removed prior to processing these products into fuels. Previous experimental results indicate the possibility of direct C–O bond breaking at elevated temperatures and low hydrogen pressures. More recent experimental results indicate that the support material is critical in understanding the C–O bond breaking step in the mechanism for oxygen removal. The proposed mechanism requires the tautomerization of the aromatic lignin degradation product to an oxygenated cyclic diene. The resulting diene is more likely to undergo oxygen removal than the aromatic species. To understand this mechanism we have explored the tautomerization and subsequent deoxygenation steps using DFT calculations. The mechanism for the model compounds of catechol and phenol C–O bond breaking under a hydrogen atmosphere is explored over the TiO<sub>2</sub>(101) and TiO<sub>2</sub>(001) surfaces of anatase titania. The effect of oxygen vacancies, the presence of absorbed hydroxyl groups, and surface adsorbed hydrogen on titania are explored for both catechol and phenol. These results are compared to the reactivity over the same reactions on a Pt(111) surface. These results provide the basis for understanding this complex mechanism and will be compared to available experimental data.

Catalyst support effects in the carbon-oxygen bond cleavage of lignin degradation products

249th National Meeting (2015)

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