(520a) Autothermal Reforming of Logistics Fuel by Noble-Metal Catalysts

Conversion of liquid hydrocarbon fuels to hydrogen and carbon monoxide mixtures has at this point been widely studied. One application of the reformate product is as a fuel for solid oxide fuel cells. Real transportation fuels, however, contain a variety of sulfur compounds that can lead to deactivation of reforming catalysts. Kerosene-type logistics fuels contain extremely high concentrations of S, making them particularly challenging to reform. We have investigated the capability of noble-metal catalysts to convert JP-8, a military logistics fuel, to syngas under both partial oxidation and autothermal reforming conditions. Catalysts comprising Pt, Pd, and Rh supported on a mixed oxide of cerium and zirconium were tested. All three metals yielded active catalysts, but Pt and Rh were found to perform better than Pd. Only Rh, however, was found to be stable over long reaction times. A 5 wt% Rh catalyst demonstrated more than 150 hours of stable performance reforming JP-8 with a sulfur content of 290 ppmw. In addition to experimental investigation, we have studied the adsorption energies of S with catalytic metal surfaces using density functional theory (DFT) under reducing and oxidizing atmospheres. Of the noble metals, DFT results indicated that Pt and Pd should be superior to Rh when challenged with S. While this appears at odds with experimental results, the discrepancy appears to be due to effects of both intrinsic activity differences between the metals and differences in catalyst stability during reforming.