Selective Hydroconversion of Oleic Acid into Aviation-Fuel-Range Alkanes over Ultrathin Ni/ZSM-5 Nanosheets

Ultrathin Ni/ZSM-5 nanosheet catalysts with different acid concentrations, B/L (Brønsted/Lewis acid sites) ratios, and nanosheet thicknesses are designed for the hydroconversion of oleic acid into aviation-fuel-range alkanes (AFRAs). The role of acid concentration/distribution and nanosheet thickness was investigated. High acid concentration enhances the hydrodeoxygenation (HDO) reaction and intrinsic deoxygenation activity because of the synergistic effect between acid sites and metal sites. The selective cracking reaction can be enhanced by tailoring nanosheet thickness and acid distribution. The thin nanosheet favors isomerization, the selective cracking reaction, as well as the generation of central branched isomers. External acid sites dominate the primary cracking and central C–C cracking of the deoxygenated products, but internal acid sites promote the deeper cracking and terminal C–C cracking. Formation of aromatics is thoroughly suppressed at low reaction temperature (≤533 K). A high AFRA yield of 41.4% is achieved over the 3 nm nanosheet catalyst with Si/Al = 300 and B/L = 0.18.