Thermodynamic and experimental study of the partial oxidation of a Jet A fuel surrogate over molybdenum dioxide

A combination of thermodynamic calculations and experimental results was used to investigate the activity and stability of molybdenum dioxide (MoO2) as a catalyst for the partial oxidation of aviation jet fuels. The surrogate fuel used in this study was n-dodecane. Our results indicate that the stability window for MoO2 is strongly affected by the O2/C molar ratio. Thus, the formation of elemental carbon on the catalyst structure can be prevented using O2/C ratios higher than 0.5. However, O2/C ratios higher than 1.0 enhance the formation of MoO3, which is volatile and leads to the irreversible loss of catalytic material. The activity was measured at 850 °C and 1 atm and our findings indicate that, within the stability window determined earlier, the production rates of H2 and CO can reach values as high as 78% and 92%, respectively. The coking resistance of MoO2 was compared with that of a commercial nickel catalyst by performing activity tests under coke-promoting conditions. Energy dispersive X-ray analysis of the spent samples shows that MoO2 is much more resistant to deactivation by coking than the commercial nickel catalyst. Based on these results, MoO2 appears to be a promising catalyst for the partial oxidation of jet fuels.

This figure describes a ternary phase diagram Mo–O–C at 850 °C and 1 atm showing the minimized Gibbs free energy in a color-scale. The results of our calculations indicate that maximum stability is attained by those regions where solid MoO2, solid Mo2C, and liquid MoO3 are present and coexist with a gas-phase consisting basically of CO2.Figure optionsDownload high-quality image (143 K)Download as PowerPoint slide