13959

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

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Noncatalytic and nonoxidative conversion of methane in a dielectric barrier discharge (DBD) reactor is examined at different temperatures, gas residence times and input powers. In addition, the ratio ofmethane to helium as a diluant, is changed in the range of O. 6 to 1.8. Results show significant synergetic effects ofplasma, temperature and helium on the methane conversion and C2+ selectivities. C2 hydrocarbons are the main products (more than 70%) of the process, however, minor amounts ofheavier hydrocarbons up to Ca are formed At an input power of230W and gas residence time of 6 sec, when the temperature increases from 100 to 20(fC, the methane conversion enhances by 33%. In the temperature of 100-35(fC, the methane conversion passes through a maximum at CH4/He ratio of1.0, at which the highest effect ofthe temperature is observed In addition, at 35(fC, when the input power increases from 140 to 230W, the CH4 conversion enhances from 20.3 to 27.0%. As the temperature increases from 100 to 35(fC, the selectivity ofethane decreases from 81.5 to 73.0%, while the selectivities ofethylene and acetylene enhances by about 40% and 270%, respectively. The frequency of effective collisions among the reactants, excited helium (He"), andfree electrons (e-) seems to increase with temperature, that in turn leads to higher methane conversions and changes in products selectivities.

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