Lignin depolymerization and upgrading to fuels and chemicals faces technical challenges in making it economically viable. One possible route for its deconstruction involves oxidation over solid acid catalysts. In this work, we explore oxidation kinetics of model compounds over titania-supported vanadia (VOx/TiO2) catalysts. Experiments revealed that single-monolayer VOx/TiO2 is capable of converting benzyl alcohol to benzaldehyde and activation of the C-H bond was identified to be rate-limiting via kinetic isotope effect analysis. Periodic density functional theory (DFT) was used to ascertain the structure of single-monolayer VOx on anatase TiO2(001) and subsequently to investigate benzyl alcohol oxidation on V2O5/TiO2(001), V2O5(001), and TiO2(001) with and without oxygen vacancies. DFT uncovered that oxygen vacancies are necessary for oxidation over V2O5(001) whereas V2O5/TiO2(001) is capable of oxidation with or without oxygen vacancies. Consistent with the experiments, our DFT results suggested C-H activation to be rate-limiting. In contrast, benzyl alcohol oxidation was not found to be energetically favorable over TiO2(001). As a result, we propose V2O5/TiO2(001) as an active surface for benzyl alcohol oxidation and suggest energetic parameters that can be used as metrics for in silico catalyst optimization.

Elucidating active VOx/TiO2 surfaces for lignin oxidation using model compounds

256th National Meeting (2018)

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