Synergetic Effects of Plasma, Temperature and Diluant on Nonoxidative Conversion of Methane to C2+ Hydrocarbons in a Dielectric Barrier Discharge Reactor

Noncatalytic and nonoxidative conversion of methane in a dielectric barrierdischarge (dbd) reactor is examined at different temperatures, gas residence times and inputpowers. in addition, the ratio ofmethane to helium as a diluant, is changed in the range of o. 6 to1.8. results show significant synergetic effects ofplasma, temperature and helium on the methaneconversion and c2+ selectivities. c2 hydrocarbons are the main products (more than 70%) of theprocess, however, minor amounts ofheavier hydrocarbons up to ca are formed at an input powerof230w and gas residence time of 6 sec, when the temperature increases from 100 to 20(fc, themethane conversion enhances by 33%. in the temperature of 100-35(fc, the methane conversionpasses through a maximum at ch4/he ratio of1.0, at which the highest effect ofthe temperature isobserved in addition, at 35(fc, when the input power increases from 140 to 230w, the ch4conversion enhances from 20.3 to 27.0%. as the temperature increases from 100 to 35(fc, theselectivity ofethane decreases from 81.5 to 73.0%, while the selectivities ofethylene and acetyleneenhances by about 40% and 270%, respectively. the frequency of effective collisions among thereactants, excited helium (he), andfree electrons (e-) seems to increase with temperature, that inturn leads to higher methane conversions and changes in products selectivities.