Abstract: It has been discovered that the coke formed in CH4 coupling under plasma can be eliminated via pure H2 discharge in the system.Eliminating coke under plasma with positive or negative high voltage in DC electric field has been compared with that in AC field.The elimination of coke takes place only on the negative of the two electrodes in DC field,while on both electrodes in AC field.The coke on the reactor walls can be eliminated with either positive or negative high voltage and in either DC or AC field.Based on the experimental facts,hypotheses of the reaction mechanism are suggested.Quantity of eliminating coke depends on diametrical ratio between reactor and the electrode,input power and electrode materials.

Key words: Eliminating coke, CH₄ coupling, Plasma