Predicting an optimal oxide/metal catalytic interface for hydrodeoxygenation chemistry of biomass derivatives

Abstract

Complex reaction pathways such as hydrodeoxygenation (HDO) of multi-oxygenated reactants like furfuryl alcohol towards 2-methylfuran can benefit from a close connection between multi-component (oxide–metal) catalytic site properties and their catalytic performance. The HDO activity can be tuned by optimizing the synergy between the individual metal oxide and metal site properties towards the HDO catalytic cycle consisting of C–O activation, C–H formation, and oxygen vacancy formation steps. Through our previously reported model of an oxide–metal interface catalyst – a TiO₂ nanorod on a Pd (111) surface, we identified the following material descriptors that dictate furfuryl alcohol HDO activity: work function (Φ), oxygen vacancy formation energy (ΔE_vac), metal–carbon binding energy (M–C_B.E.), and extent of metal–metal oxide interfacial charge transfer (q). The descriptors were examined over the interface with the composition altered towards closed pack metals: Ag, Au, Cu, Pd, Rh, Ru and Zn, and monolayer surfaces of Ag, Au, Co, Cu, Fe, Ir, Ni, Pt, Rh, Ru and Zn metals atop Pd (111). We identified a greater stabilization of the C–O activation transition state, the key HDO step, through electronic charge redistribution at the interface, facilitated by a higher metal work function. Stronger metal–carbon binding dictates the favorable hydrogenation of the resulting organic fragment. The role of these descriptors was further investigated under experimentally relevant hydrogenation reaction conditions of H₂ and hydrocarbons partial pressures. Such fundamental knowledge of the descriptors dictating HDO can provide opportunities for further tuning the structural, electronic, and chemical properties of a multicomponent interface to achieve optimal HDO activity.