Boosting in-situ hydrodeoxygenation of fatty acids over a fine and oxygen-vacancy-rich NiAl catalyst

Hydrodeoxygenation (HDO) of fatty acids into long-chain alkanes for aviation fuels with alcohol hydrogen donor at mild condition over Ni-based catalyst is a practicable subject. However, highly active sites design for Ni-based catalyst remains significant challenges. Herein, a fine NiAl particle catalyst with numerous oxygen vacancy sites was fabricated via hydrothermal and reduction treatment. Introduction of small amount of Al species into Ni catalyst not only reduces the Ni particle size exposing plenty of active sites, but also generates oxygen vacancies in AlOx and sets up charge transfer in Ni-AlOx interfaces, thus guarantees the excellent in-situ HDO activity of fatty acids using isopropanol as hydrogen donor. Density functional theory calculation results further reveal that Ni (111) modified by AlOx with oxygen vacancy improves the charge density in Ni-AlOx interface and enhances the adsorption of fatty acid, facilitating the hydrodeoxygenation process. Benefiting from these attributes, Ni–Al0.33Ox presented superior catalytic activity and stability, which achieved 93.2% yield of n-heptadecane at 250 °C and was able to reuse at least 4 times. Therefore, the as-prepared Ni–Al0.33Ox is a promising Ni-based catalyst for alkanes production via in-situ HDO of fatty acids at mild conditions.