Surface engineering of earth-abundant Fe catalysts for selective hydrodeoxygenation of phenolics in liquid phase

Development of inexpensive sulfur-free catalysts for selective hydrogenolysis of the C–O bond in phenolics (i.e., selective removal of oxygen without aromatic ring saturation) under liquid-phase conditions is highly challenging. Here, we report an efficient approach to engineer earth-abundant Fe catalysts with a graphene overlayer and alkali metal (i.e., Cs), which produces arenes with 100% selectivity from liquid-phase hydrodeoxygenation (HDO) of phenolics with high durability. In particular, we report that a thin (a few layers) surface graphene overlayer can be engineered on metallic Fe particles (G@Fe) by a controlled surface reaction of a carbonaceous compound, which prevents the iron surface from oxidation by hydroxyls or water produced during HDO reaction. More importantly, further tailoring the surface electronic properties of G@Fe with the addition of cesium, creating a Cs-G@Fe composite catalyst in contrast to a deactivated Cs@Fe one, promotes the selective C–O bond cleavage by inhibiting the tautomerization, a pathway that is very facile under liquid-phase conditions. The current study could open a general approach to rational design of highly efficient catalysts for HDO of phenolics.