Liquid-Phase Oxidation Kinetics:  Paraffin Blends

• Published in: Energy & fuels 1998-11, Vol.12 (6), p.1241-1244
• Main Authors: Pickard, James M, Jones, E. Grant
• Format: Article
• Language: English
• Subjects: Applied sciences; Crude oil, natural gas and petroleum products; Energy; Exact sciences and technology; Fuels; Petroleum products, gas and fuels. Motor fuels, lubricants and asphalts
• ISSN: 0887-0624; 1520-5029
• DOI: 10.1021/ef980063r

Kinetics of O2 depletion in an air-saturated (74.7 ppm O2) paraffin blend (Exxsol D-80) were conducted with a near-isothermal flowing test rig using passivated heat-exchanger tubing over the range 408−438 K. Hydroperoxide formation was monitored by cyclic voltammetry. Autoxidation data are consistent with an initiation mechanism involving hydroperoxide dissociation; the kinetic data are independent of the initial O2 concentration. Data analysis yielded the following rate parameters:  log(k i/s-1) = (15.2 ± 1.6) − (33.1 ± 3.1)/θ, log[k iv(k i/2k v)1/2/M-1/2s-1] = (9.5 ± 0.2) − (26.3 ± 0.4)/θ, and log[(k iv/2k v)1/2/M-1/2s-1/2] = (3.3 ± 1.3) − (12.5 ± 2.6)/θ (where k i, k iv, and k v are rate constants for initiation, propagation, and termination, respectively, θ = 2.303RT kcal mol-1, R is the ideal-gas-law constant, and T is absolute temperature). Results are discussed with reference to kinetic parameters reported for conventional aviation fuels and normal paraffins.