Hydrodeoxygenation processes via catalytic transfer hydrogenation (CTH) have provided a sustainable and selective method in converting biomass-derived furfural to 2-methylfuran, a potential drop-in fuel additive. Although high yields have been attained (roughly 80%) over a Ru/RuOx/C catalyst using 2-propanol as the hydrogen source, mechanistic understanding of the cascade reaction has remained elusive. Through a series of isotopic labeling and kinetic studies using perdeuterated 2-propanol (2-propanol-d8), we have shown key insights into the synergistic effect of both the Ru and RuOx phases. Hydrogenation of furfural proceeds primarily through a Lewis acid-catalyzed Meerwein-Pondoorf-Verley (MPV) hydrogenation over the RuOx sites, where a hydrogen atom is transferred in one, concerted step. Meanwhile, we have shown the existence of ring activation as a major, if not dominant, pathway in the hydrogenolysis of furfuryl alcohol to 2-methylfuran.
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