Molecular Insights into Guaiacols Hydrodeoxygenation on Nickel Nanoparticle Surfaces

The hydrocarbon fuels from the pyrolysis of lignocellulosic biomass can serve as a substitute for fossil fuels, but their commercialization is limited by a high content of oxygenates. Hydrodeoxygenation (HDO) of the lignin-derived compounds, such as guaiacol, is essential to produce high-quality biofuels, which requires a deep understanding of the HDO mechanism at the molecule scale. Herein, the reactive force field molecular dynamics (ReaxFF-MD) simulations are used to elucidate the HDO mechanism of guaiacols on the Ni nanoparticle surface. We find that the demethylation of guaiacols is the main pathway for the HDO process of guaiacols on Ni-based catalyst surfaces, which produces catechol via the scission of the CarylO–CH3 bond and then proceeding the hydrogenation and dehydration of catechols and phenols to produce benzenes. The hydrogen content in the system does not affect the pathway, but only affects the extent of the HDO reaction. Our results also provide a clear reaction network for the HDO mechanism of guaiacol on a Ni-based catalyst, providing theoretical guidance to the understanding and design of advanced HDO systems for lignin-derived compounds.