Mechanism unraveling for efficient hydrodeoxygenation of fatty acids/esters over highly stable Ni/Nb2O5-SiO2 catalyst

The conventional hydrodeoxygenation process for sustainable aviation fuel production using Al2O3-supported Ni-Mo sulfide catalyst faces dual challenges: sulfur contamination and catalyst hydrothermal instability. This work develops a hydrothermally stable 5% Ni/Nb2O5-SiO2 catalyst, where strong metal-support interaction drives Nb to Ni electron transfer to form oxygen vacancies activating oxygen-rich groups. The addition of SiO2 increases the specific surface area of the catalyst, while niobium oxide enhances its water resistance. The catalyst exhibits highly catalytic activity in the hydrodeoxygenation of methyl palmitate with >99% conversion and 96% liquid alkane yield, maintaining activity over a 1000-h on a fixed-bed continuous-flow reactor. Furthermore, the catalyst demonstrated stable and reliable performance over a cumulative period of 500 h, comprising 240 h during the hydrodeoxygenation of palm oil and an additional 260 h of continuous operation with waste cooking oil. This work provides a green, non-sulfur, and stable approach for the production of renewable fuels.