Tuning hydroconversion performance of n-hexadecane over Ni/silica-alumina catalysts: Role of Si/Al ratio and nickel loading

This study introduces a cost-effective approach to sustainable aviation fuel (SAF) production by systematically tuning the Si/Al ratio and Ni loading on silica-alumina (Siral) supports to optimize metal-acid balance during hydroconversion of Fischer-Tropsch (FT) waxes. Using n-hexadecane as a model compound, it has been demonstrated that support composition and Ni content strongly influence Brønsted acidity (0.73–1.94 mmol g −1 ), Ni dispersion (7.0–27.8 %), and surface area (270–326 m 2 g −1 ). Catalytic tests at 350 °C and 60 bar H 2 in batch reactor showed that Ni10/Siral40 achieved the best performance, with 67 % conversion and 27 % isomer selectivity. Lower SiO 2 /Al 2 O 3 ratios reduced acidity and favored hydrocracking. Similarly, excessive Ni loading led to pore blockage and decreased selectivity, whereas moderate loading ensured optimal metal-acid balance. These findings demonstrate the novelty of tuning the support composition (using a wide range of supports) and Ni loading enables control over acidity, dispersion, and porosity, which are key parameters for maximizing SAF yield. On the other hand, the results obtained in a fixed-bed reactor using the optimal conditions determined in batch mode show lower conversion (44 %) but considerably higher isomer selectivity (77 %). This work reports, for the first time, the use of Ni/Siral catalysts in continuous-flow reactors for the hydroconversion of Fischer-Tropsch waxes. • Moderately acidic supports with non-noble Ni enable cost-efficient SAF production • The increase in temperature leads to higher cracking products yield • Higher SiO 2 /Al 2 O 3 boosts acidity and selectivity toward isomers • Nickel loading tunes metal–acid balance and reaction pathways • Ni10/Siral40 shows best performance and robust continuous-flow behavior