Catalysis of Jet-A Fuel Autoxidation by Fe2O3

Experiments on the kinetics of O2 depletion in air-saturated (65 ppm O2) Jet-A (POSF-2827) fuel containing 4 ppm Fe2O3 were conducted with a near-isothermal flowing test rig (NIFTR) using passivated heat-exchanger tubing over the range 418−468 K. The kinetic data are consistent with an oxidation mechanism involving dissociation of an Fe2O3−hydroperoxide adduct (formed by adsorption of hydroperoxide on the Fe2O3 surface) and subsequent H-atom abstraction by surface-adsorbed radicals. Data analysis yielded the following rate parameters: log(k ap/M-1 s-1) = (11.68 ± 0.46) − (27.68 ± 0.94)/θ and log(k vii K eq/M-1 s-1) = (9.20 ± 0.75) − (18.6 ± 1.5)/θ (where k ap is the apparent rate constant, k vii is the rate constant for the dissociation of the Fe2O3−hydroperoxide adduct, K eq is the equilibrium constant for adsorption of hydroperoxide on Fe2O3, and θ = 2.303RT kcal mol-1, where R is the ideal-gas-law constant and T is absolute temperature). Analysis of the surface insolubles for neat and doped fuel indicated that both the maximum and the magnitude of the surface deposition decreased for the Fe2O3 catalysis of the autoxidation and suggested that precursors for surface deposition are scavenged by Fe2O3 particles.