On design of plasma jet reactor for non-oxidative methane conversion

Non-oxidative methane coupling in an atmospheric pressure plasma jet reactor with an internal diameter of 3.0 mm has been studied. The jet reactor consisted of a quartz tube surrounded by a copper ring and a stainless-steel tube, which were separated by a variable distance. The stainless-steel tube (inner diameter: 1.0 mm, outer diameter: 1.5 mm) served as high voltage electrode and gas inlet. The jet characteristics with different tip angles of the high voltage electrode were investigated using voltage-current waveforms and gas analysis at a constant methane flow rate of 100 ml min^-1. The effect of the length of the ground electrode and the gap between the electrodes on conversion, C₂ selectivity and energy efficiency has been studied. The methane conversion was nearly tripled with a sharp angle of the electrode (15°), while the energy consumption was reduced from 150 to 55 kJ mol_C ^-1. The carbon deposition was also reduced.