(346i) Predicting an Optimal Oxide/Metal Interface Catalyst for Hydrodeoxygenation Chemistry of Biomass Derivatives

Selective C-O cleavage is the most difficult chemical transformation en route to fuels production from biomass derivatives such as furfuryl alcohol. Metal oxide-metal interfaces have recently been used to manipulate catalytic selectivity in such multistep reactions, and also hinder non-selective decarbonylation (DCO, C-C activation). Our DFT interfacial model of TiO₂/Pd core-shell catalyst in the form of rutile TiO₂ (110) nanowire over Pd (111) provides qualitative mechanistic determination of the role of interfacial active sites towards deoxygenation and decarbonylation[1]. A much-lowered barrier to hydrodeoxygenation (HDO) is obtained over TiO_2-x/Pdoxygen deficient interface model relative to supported Pd catalysts (0.20 eV barrier vs 0.95 eV on Pd (111)).

With this mechanistic insight, we have extended this model to predict an optimal combination of oxides and metal catalyst with interfacial properties that combine hydrogenation and redox requirements of HDO. Descriptors that dictate the synergy between the oxide and metals’ functionalities for HDO at the oxide/metal interface are evaluated, including the interfacial reducibility, metal–oxygen bond strength, metal-carbon binding energy, metal’s work function or its relative d-band center. We identify a greater stabilization of the C-O activation transition state 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 mechanistic study is also successfully extended to predict deoxygenation of other stringent oxygenates like m-cresol, phenols etc., to establish more generic correlations aimed to optimize the overall HDO chemistry, hydrogen activation and subsequent hydrogenation of different oxygenated biomass derivatives.

[1] S. Deo, W. Medlin, E. Nikolla, M.J. Janik, Reaction paths for hydrodeoxygenation of furfuryl alcohol at TiO2/Pd interfaces, Journal of Catalysis, 377 (2019) 28-40.