Plasma-Based CH(4) Conversion into Higher Hydrocarbons and H(2): Modeling to Reveal the Reaction Mechanisms of Different Plasma Sources

[Image: see text] Plasma is gaining interest for CH(4) conversion into higher hydrocarbons and H(2). However, the performance in terms of conversion and selectivity toward different hydrocarbons is different for different plasma types, and the underlying mechanisms are not yet fully understood. Therefore, we study here these mechanisms in different plasma sources, by means of a chemical kinetics model. The model is first validated by comparing the calculated conversions and hydrocarbon/H(2) selectivities with experimental results in these different plasma types and over a wide range of specific energy input (SEI) values. Our model predicts that vibrational–translational nonequilibrium is negligible in all CH(4) plasmas investigated, and instead, thermal conversion is important. Higher gas temperatures also lead to a more selective production of unsaturated hydrocarbons (mainly C(2)H(2)) due to neutral dissociation of CH(4) and subsequent dehydrogenation processes, while three-body recombination reactions into saturated hydrocarbons (mainly C(2)H(6), but also higher hydrocarbons) are dominant in low temperature plasmas.