Kinetic of propane in homogeneous high pressure low temperature plasmas of atmospheric gases

The kinetic of propane in non-thermal plasmas of N$_{2}$/O$_{2}$ mixtures is currently under study owing to applications such as cleaning of polluted air streams or plasma assisted ignition and combustion. We have recently suggested that, for C$_{3}$H$_{8}$ diluted in N$_{2}$, quenching collisions of the nitrogen metastable states on the hydrocarbon leads to produce H$_{2}$ and propene (N. Moreau et al., to appear in J. Phys. D : Appl. Phys.). The present work deals with the effect of oxygen addition on propane consumption in a photo-triggered discharge (homogeneous plasma) working at 460 mbars. By-products are identified and their concentrations are quantified (chromatography) as functions of the O$_{2}$ concentration (up to 20{\%}), at 0.5{\%} propane concentration. H$_{2}$ concentration decreases when the oxygen concentration increases, but do not drop to zero in the air-like mixture. This effect is explained using a self-consistent 0D discharge and kinetic model. The removal of C$_{3}$H$_{8}$ and the production of H$_{2}$ follow from a balance between quenching processes and oxidation kinetic of the hydrocarbon. The model predictions are also compared to the measure of the absolute OH-radical density as function of time in the discharge afterglow (UV-absorption).