Carbon Dioxide Reforming of Methane Using a Dielectric Barrier Discharge Reactor: Effect of Helium Dilution and Kinetic Model

Abstract

The carbon dioxide reforming of methane to synthesis gas was investigated in a dielectric barrier discharge reactor at room temperature. The influence of dilution of reactants by helium was studied. We showed that, at a fixed contact time, the conversions of CH 4 and CO 2 increase when the amount of helium in the gas mixture increases. This result is attributed to the ''penning ionization'' phenomenon, which corresponds to an energy transfer from excited He to molecules in ground state (CH 4 , CO 2 ). The selectivity to products is affected by the dilution factor. As soon as helium is present in a large amount the formation of products resulting from recombination of methyl radicals (such as C 2 , C 3 and C 4 ) is less favourable due to the lowest probability of collisions to proceed. A kinetic model is proposed based on the assumption that the reactant molecules CH 4 or CO 2 are attacked by active species produced by the plasma discharges, and the production of this active species are function of the plasma power. This model which takes into account the dilution by helium fits particularly well the experimental data we obtained.

Product analysis of methane activation using noble gases in a non-thermal plasma

“…For all noble gases, methane conversion increased linearly with increasing discharge power, even at the low applied voltages used in the cases of Kr and Xe at which discharges were weakly developed and did not fill the discharge region completely. This linearity with discharge power agrees with previous studies [20][21][22]. The differences in methane conversion upon changing the noble gas were noticeable; Kr was the most effective for methane activation as the additive.…”

Investigation on Plasma‐Driven Methane Dry Reforming in a Self‐Triggered Spark Reactor

“…The formation of ethane can be attributed to the recombination of CH 3 radicals (28), originating from the dissociation of CH 4 (2) or from its reaction with atomic oxygen (15) …”

Carbon dioxide dissociation to carbon monoxide by non-thermal plasma

“…In the presence of He, another CO 2 activation can occur through electrons energy transfer to He atoms to form excited He atoms according to Reactions (18) and (19) [29,30]:…”