Hydrodeoxygenation of dibenzofuran over SiO2, Al2O3/SiO2 and ZrO2/SiO2 supported Pt catalysts

Abstract

The surface of silica with mesopores (SiO₂) was post-modified by the deposition of highly dispersed Al₂O₃ or ZrO₂ oxides. Loading of Pt on the modified silica supports yielded higher metal dispersion with respect to the parent silica based on the CO chemisorption and transmission electron microscopy results. Hydrodeoxygenation (HDO) of dibenzofuran (DBF) over the as-prepared Pt catalysts mainly proceeds via the hydrogenation of the aromatic rings, which is followed by the cleavage of the C–O bond to produce oxygen-free hydrocarbons. Preferable hydrogenation of the aromatic rings is observed over the smaller Pt nanoparticles. The relatively strong acidic properties of Al₂O₃/SiO₂ or ZrO₂/SiO₂, revealed by the NH₃-TPD profiles, promote the selective C–O bond cleavage of hexahydrodibenzofuran to alter the HDO reaction pathway. The small sized Pt nanoparticles supported on the Al₂O₃ or ZrO₂ modified silica supports show superior HDO performance with enhanced deoxygenation ability to those over unmodified silica. According to the pseudo-first-order kinetics analysis, the fitted HDO rate constant follows the order: Pt/Al₂O₃/SiO₂ > Pt/ZrO₂/SiO₂ > Pt/SiO₂ under a constant temperature, which is attributed to the cooperative function of the dispersed metal particles and the acidic sites of supports.