Counterintuitive Catalytic Reactivity of the Aluminum Oxide Passivation Shell of Aluminum Nanoparticles Facilitating the Thermal Decomposition of exo-Tetrahydrodicyclopentadiene (JP-10)

High energy density aluminum nanoparticles (AlNPs) have been at the center of attention as additives to hydrocarbon jet fuels like exo-tetrahydrodicyclopentadiene (JP-10, C10H16) aiming at the superior performance of volume-limited air-breathing propulsion systems. However, a fundamental understanding of the ignition and combustion chemistry of JP-10 in the presence of AlNPs has been elusive. Exploiting an isomer-selective comprehensive identification of the decomposition products in a newly designed high-temperature chemical microreactor coupled to vacuum ultraviolet photoionization, we reveal an active low-temperature heterogeneous surface chemistry commencing at 650 K involving the alumina (Al2O3) shell. Contrary to textbook knowledge of an inactive alumina surface, this unconventional reactivity, where oxygen is transferred from alumina to JP-10, leads to generating cyclic, oxygenated organics like phenol (C6H5OH) and 2,4-cyclopentadiene-1-one (C5H4O)-key tracers of an alumina-mediated interfacial chemistry. This counterintuitive reactivity transforms our knowledge of the (catalytic) processes of alumina-coated AlNPs on the molecular level.

Automated summary

Researchers have discovered an active heterogeneous surface chemistry between aluminum nanoparticles (AlNPs) and alumina in hydrocarbon jet fuels, which challenges previous understanding of alumina’s reactivity.