Ni-W Catalysts Supported on TiO2-Al2O3 for Efficient Green Diesel Production: “Standard” vs “Keggin” Comparison

In order to obtain an efficient Ni-W catalyst for green diesel production, a new preparation method based on Keggin-type polyoxotungstates supported on TiO₂-Al₂O₃ was developed. The as-obtained catalyst (NiPW/TiO₂-Al₂O₃) was compared to a conventionally synthesized catalyst (NiW/TiO₂-Al₂O₃) during each step of the catalyst preparation. Depending on the preparation method, different Ni-W species were formed. Afterward, the catalysts were sulfided, and the Lewis and Brønsted acid concentrations were determined. Finally, all catalysts were tested in the hydroprocessing of soybean oil. The results show a direct correlation between hydroprocessing activity and Lewis/Brønsted acidity. The NiPWS/TiO₂-Al₂O₃ catalyst presents the highest value of Lewis acid sites (227 μmol/g). Consequently, this catalyst shows deoxygenation activity values 10 and 55% higher than those for NiWS/TiO₂-Al₂O₃ and NiWS/Al₂O₃-reference, respectively. The NiPWS/TiAl catalyst exhibits the highest selectivity to C ₁₈ among all of the catalysts studied, producing green diesel with the highest added value.