Reaction paths for hydrodeoxygenation of furfuryl alcohol at TiO₂/Pd interfaces

Metal–metal oxide interfaces can manipulate catalytic selectivity in multistep reactions, including hydrodeoxygenation (HDO) of biomass derivatives like furfuryl alcohol. These interfaces combine active sites of different functionalities towards hydrogen activation, HDO and subsequent hydrogenation. However, examining the interplay between these different sites is essential to achieve control over the interfacial properties, and thus over the reaction selectivity towards 2-methylfuran. Herein, through DFT calculations, we investigate the role of TiO₂ encapsulated Pd interfacial sites towards dictating HDO product selectivity. A rutile TiO₂ (1 1 0) nanowire over a Pd (1 1 1) surface is used as the interfacial model. TiO₂/Pd sites are found to provide a bifunctional role at the interface. The results show that TiO₂ generates reduced oxide sites such that CߝO bond of furfuryl alcohol is activated relative to Pd (1 1 1), with the alcohol group re-oxidizing the reduced site. The Pd surface activates H₂ and enables hydrogenation to the final product. Consequently, deoxygenation is accelerated over a TiO_2−x/Pd oxygen deficient interface, with an approximate kinetic analysis suggesting that reduced interfacial sites accelerate direct deoxygenation by ∼10⁸ at 443 K, altering the Pd selectivity from the undesired furan product to the desired 2-methylfuran.