Influence of Metal-Support Interaction on Anisole Hydrodeoxygenation Activity on Noble Metal TiO2-Based Catalysts

Abstract Hydrodeoxygenation (HDO) is a critical process for upgrading biomass-derived feedstocks. It enables the removal of oxygen, which improves stability, energy density, and compatibility with existing fuel infrastructure. This study examines the catalytic performance of titania-supported noble metals (ruthenium [Ru], rhodium [Rh], palladium [Pd], silver [Ag], iridium [Ir], platinum [Pt], and gold [Au]) in the HDO of anisole, a model compound for lignin-derived oxygenates. The catalysts were prepared via incipient wetness impregnation and characterized using X-ray fluorescence (XRF), nitrogen physisorption (N 2 -physisorption), X-ray diffraction (XRD), carbon monoxide (CO) chemisorption, thermogravimetric reduction (TPR), ammonia-temperature-programmed desorption (NH 3 -TPD), hydrogen-temperature-programmed desorption (H 2 -TPD), and transmission electron microscopy (TEM). The results reveal that metal-support interactions significantly influence metal dispersion, activity, and selectivity. Rh and Pt catalysts exhibited the highest anisole conversion and benzene selectivity due to their small particle sizes, high dispersion, and strong hydrogen spillover effects. Conversely, Ag and Au catalysts demonstrated limited activity: Ag induced a phase transition in TiO 2 , and Au formed large particles. Residual chlorine from precursor salts notably affected the performance of Ru/TiO 2 and Ir/TiO 2 . Reducible TiO 2 support was found to enhance demethoxylation activity synergistically compared to SiO 2 , highlighting the importance of support reducibility for HDO. This work provides insights into the structure-function relationships of noble metal/TiO 2 catalysts.