Chemoselective Hydrogenation of Ring‐Strained Monoterpenes: A Route to High‐Performance Sustainable Aviation Fuels

Abstract

Sabinene and 3‐carene, bio‐based monoterpene precursors to high‐performance jet fuels, are chemoselectively hydrogenated with reduced PtO2 at low temperatures (263–298 K), to yield products in which the alkene groups are saturated, whereas cyclopropane rings from the parent hydrocarbons are conserved. Sabinene is selectively converted to a 79:21 mixture of cis:trans‐thujane (1), whereas 3‐carene is converted to a 72:28 mixture of cis:trans‐carane (3). For comparison, the fully hydrogenated species tetrahydrosabinene (2) and 1,1,4‐trimethylcycloheptane (4) are prepared by hydrogenation with Pd/C. To evaluate 1−4 as advanced jet fuel blendstocks, several key fuel properties are measured. Compared with conventional jet fuel, the hydrogenated monoterpenes exhibit up to 8.6% higher density, 1.3% higher gravimetric net heat of combustion (NHOC), 9.7% higher volumetric NHOC, and 64% lower kinematic viscosity at −20 °C. These properties suggest that 1−4 are valuable blendstocks for conventional jet fuel or sustainable aviation fuel, providing enhanced operability and performance.