Insight into the Mechanisms of Middle Distillate Fuel Oxidative Degradation. Part 1: On the Role of Phenol, Indole, and Carbazole Derivatives in the Thermal Oxidative Stability of Fischer-Tropsch/Petroleum Jet Fuel Blends

The U.S. Air Force (USAF) has committed to use 1/1 volumetric blends of conventional jet fuels with Fischer-Tropsch (FT) derived fuels by 2016. Previous work by Balster et al. (Balster, L. M.; Zabarnick, S.; Striebich, R. C.; Shafer, L. M.; West, Z. Energy Fuels 2006, 20, 2564-2571) examined the relationship between thermal oxidative deposit and the concentration of various polar compounds present in 20 petroleum jet fuels. The thermal oxidative stability of FT blends, derived from four conventional jet fuels selected from the study of Balster et al. (Balster, L. M.; Zabarnick, S.; Striebich, R. C.; Shafer, L. M.; West, Z. Energy Fuels 2006, 20, 2564-2571), was examined with the Penn State University (PSU) flow reactor. Excellent linear correlations were found between fuel thermal oxidative deposit and indigenous fuel phenol, indole, and carbazole concentrations. This data is consistent with a mechanism previously proposed for the thermal oxidative degradation of both jet and diesel fuels (Beaver, B.; Gao, L.; Burgess-Clifford, C.; Sobkowiak, M. Energy Fuels 2005, 19, 1574-1579).