Mechanism and kinetics of self-sensitized photocycloaddition of cyclohexenone and norbornene

Solar-driven conversion of renewable biomass resources into high-density hydrocarbon fuels can effectively realize biomass valorization and renewable energy conversion. In this work, an efficient self-sensitized [2 + 2] photocycloaddition process is explored to develop highly strained fuel with high yield using norbornene and biomass-derived cyclohexenone as feedstocks. The enhancement mechanism is revealed by phosphorescent measurement and theoretical calculation, and a reasonable reaction path for self-sensitized [2 + 2] co-cycloaddition is proposed. When using methanol as solvent, the apparent activation energy of co-cycloaddition is 21.37 W/mol, which is lower than that of self-cycloaddition (31.57 W/mol). Importantly, the jet-fuel-range highly strained fuel has high density (0.986 g/cm3) and high volumetric net heat of combustion (41.14 MJ/L), which are 5.34% and 4.39% higher than those of JP-10, respectively. This work proposes a green and effective pathway for the preparation of high-performance hydrocarbon fuel with polycyclic-asymmetric structure.