Production of H2 from plasma methane decomposition in Ar/CH4 mixtures at atmospheric pressure

Cold plasmas have proven their effectiveness for methane conversion with the use of several types of discharges. This study aims to contribute to the understanding of the kinetic processes involved in Ar/CH4 mixtures. An UV photo-triggered discharge is used, in which the plasma is homogeneous, the electric field uniform and the deposition of energy in the plasma controllable. CH4 and by-products concentrations are measured by chromatography. The moderate values of E/N, associated with the preceding properties, allows a 0D self-consistent modelling with local field approximation. It is then possible to propose an accurate detailed kinetic scheme by comparing experimental results to calculations, as it was performed for other molecules [1]. The experiment emphasizes that H2 is the main by-product, the concentration of detected carbon in compounds with less than 4 C being very small compared to the converted CH4. A lack of H is observed, suggesting the formation of heavier hydrocarbons and/or solid compounds. A high production rate of H2 is also predicted by the model, although kinetic data taken from the literature do not allow to explain all experimental results.