We report a computational investigation of the reaction mechanism of levulinic acid (LA) to γ-Valerolactone (GVL) using DFT calculations and mean-field microkinetic modeling in both vapor and liquid phase reaction conditions. In vapor phase calculations, our model predicts a dominant reaction route that involves three elementary reaction steps, (i) hydrogenation of the ketone group of LA, i.e. C-H bond formation, to yield a surface alkoxy intermediate, (ii) cyclization of the alkoxy intermediates, and (iii) hydroxyl group removal to form the final product GVL. This pathway deviates from the previously proposed mechanism that involves formation of HPA. At high temperature, our model confirms the experimental observation that the AGL formation pathway is responsible for reversible catalysts deactivation. Next, our liquid phase results indicate that polar solvents (i.e. water) have a beneficial effect on the reaction kinetics of the hydrodeoxygenation of LA. In contrast, non-polar solvents (1,4-dioxane) have a detrimental effect on the reaction kinetics, as confirmed by several experimental studies, due to high solvent coverage on the Ru surface.

Theoretical investigation of the catalytic hydrodeoxygenation of levulinic acid over Ru(0001) surface

253rd National Meeting (2017)

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