Synthesis of Jet-Fuel Range Cycloalkanes from the Mixtures of Cyclopentanone and Butanal

High-density (0.82 g mL–1) jet-fuel range cycloalkanes were synthesized in high overall yields (∼80%) by the aldol condensation of cyclopentanone and butanal followed by hydrodeoxygenation (HDO). Among the investigated solid-base catalysts, magnesium–aluminum hydrotalcite (MgAl-HT) exhibited the highest activity for the solvent-free aldol condensation of cyclopentanone and butanal. The excellent performance of MgAl-HT was rationalized by the synergism between strong base and weak acid sites on the surface of this material. The aldol condensation products were further hydrodeoxygenated to butylcyclopentane and 1,3-dibutylcyclopentane over the Ni/SiO2, Pd/SiO2, and bimetallic Ni–Pd/SiO2 catalysts. Compared to the Ni/SiO2 and Pd/SiO2 catalysts, the bimetallic Ni–Pd/SiO2 catalyst exhibited higher activity for the solvent-free HDO reaction. Over the 4%Ni–1%Pd/SiO2 catalyst, high carbon yield (88.0%) of butylcyclopentane and 1,3-dibutylcyclopentane was achieved at 503 K. According to the characterization results, the excellent performance of Ni–Pd/SiO2 catalyst can be explained by the formation of Ni–Pd alloy.