Methane Conversion Using Gliding Arc Discharge Plasma

Methane conversion is very difficult to occur due to the high dissociation energyof C–H bond. Threre are some major dravbacks for traditional method of CH₄conversion reaction: the larger energy consumption, the higher equipment cost and thedepth oxidation inevitably. Gliding arc discharge plasma integrate non-equilibriumplasma and thermal plasma advantages which is able to produce energetic radicalspecies, more active compared with the other types of non-thermal plasma.The content of the methane decomposition, CH₄-H₂O reforming, CH₄-CO₂reforming and CH₄-CO₂-H₂O reforming via gliding arc discharge were investigated.In methane conversion process, the optimum reactor sizes consisted of a nozzleinner diameter of0.1mm, distance between nozzle and electrode of13mm,unsymmetrical electrode （up arc41°, down arc76°） and without filler. Optimumconditions for producing C₂hydrocarbons from CH₄were suggested. The maximummethane conversion of43.4%was obtained under the optimum conditions. Also, C₂hydrocarbons selectivity, C₂hydrocarbons yield and SER were37.8%,87.2%and2.09kJ·mmol^-1, respectively. It was found that H₂was conducive to C₂hydrocarbonsselectivity. By adding H₂，C₂hydrocarbons selectivity approached100%. However,the special energy requirement increased with the increase of H₂.In the process of steam reforming of CH₄, the optimum conditions showed theCH₄conversion of53.1%on the basis of CH₄/Ar ratio of0.23, total flow rate of74mL·min^-1, input voltage of26V, and H₂O/total ratio of0.47. At this condition, C₂hydrocarbons selectivity, C₂hydrocarbons yield and SER were90.1%,47.8%and1.56kJ·mmol^-1, respectively. Adding CO₂into CH₄system can prohibit carbondeposition efficiently. The main products of CH₄-CO₂refroming were CO, H₂and C₂hydrocarbons. CH₄/CO₂ratio had important effect on H₂/CO ratio. In the CH₄-CO₂-H₂O reforming, with increase of steam/gas（S/G） ratio, CH₄conversion increasedwhile CO₂conversion increased first and then decreased. In comparison withCH₄-CO₂reforming, CH₄-CO₂-H₂O reforming had higher conversions of CH₄andCO₂.