Sustainable production of high-energy-density fuel with natural terpenes and phenols

High-energy-density (HED) fuels can enhance the payload and range performance of aircraft, holding strategic importance in the field of air defense. However, conventional petroleum-derived HED fuels face growing challenges related to resource depletion and greenhouse gas emissions. In response to the urgent need for sustainable alternatives, we develop an efficient ring-increasing strategy using natural terpenes as feedstocks to construct polycyclic frameworks suitable for HED fuel applications. The process includes acid-catalyzed ringincreasing alkylation of renewable terpenes with phenols and subsequent hydrodeoxygenation over bifunctional Pd/C and H-Y catalyst system. Benefiting from their strained and polycyclic architectures, the eucalyptus oil-derived biofuel exhibits a density of 0.914 g/mL, combustion heat of 40.1 MJ/L, freezing point below -67 °C and viscosity of 34.5 cSt, while the turpentine oilderived fuel achieves even higher energy density. The high density and good low-temperature fluidity render these fuels as promising sustainable alternatives to conventional petroleum-based HED fuels.