Oligomerization and carbon dioxide reforming of methane in a dielectric-barrier discharge-plasma system

At room temperature and under atmospheric pressure, direct oligomerization of CH4 to C-2 and C-3 hydrocarbons and CO2 reforming of CH4 to CO and H-2 in the Ar stream have been investigated by a nonthermal dielectric-barrier discharge-plasma reactor. Conversion and selectivity of the reactions strongly depended on input voltage, on concentration and on the ratio of the reactant. It was confirmed that the reactions in the Ar stream occurred where the input voltage was above ca. I, which was considered as the break-down voltage of Ar. The intensity of emission spectra due to Ar excitation decreased with increasing reactant concentration. From these points of view, the reactions in the plasma zone were, therefore, found to proceed via energy transfer from excited species of Ar atoms to the reactant molecules in the plasma zone. The energy efficiency of the reforming reaction of the present plasma system increased with decreasing input voltage.