TEOS-modified Ni/ZSM-5 nanosheet catalysts for hydroconversion of oleic acid to high-performance aviation fuel: Effect of acid spatial distribution

Ni/ZSM-5 nanosheet catalysts with different Si/Al ratios were modified by chemical liquid deposition (CLD) of tetraethoxysilane (TEOS) to tailor their acid spatial distribution. Their catalytic performance was evaluated with the hydroconversion of oleic acid to aviation-fuel-range-alkanes (AFRAs) at different reaction temperatures and H2 pressures. The modified catalysts inherit the nanosheet structure with decreased external Brønsted acid concentration, especially the strong one. External Brønsted acid sites mainly favor the cracking of the deoxygenated products (C17/C18). Internal Brønsted acid sites mainly enhance the isomerization of the linear AFRAs. And the catalytic activity of the external Brønsted acid sites was more sensitive to reaction temperature than that of the internal ones. The deoxygenation and cracking reactions were also more sensitive to H2 pressure compared to the isomerization reaction. High AFRA selectivity of 51.4% as well as high iso/n-alkanes ratio of 1.7 were achieved at 250 °C and 10 bar over NS200(1).