Abstract
Conventional catalytic processes of CH4 conversion to produce synthesis gas require high temperature and high pressure. Nonthermal plasma is considered to be a promising technology for CH4 conversion since it can operate in ambient conditions. In this study, a multi-stage gliding arc discharge system was employed in this study to investigate the effects of stage number, CH4/O2 molar ratio, total flowrate, frequency, voltage, and gap distance on CH4 and O2 conversion and product distribution. Air was used instead of pure O2 in the feed gas since it can reduce investment and operating cost. The results showed that increasing stage number, voltage or gap distance enhanced both CH4 and O2 conversion in contrast with the effects of increasing CH4/O2 molar ratio, total flowrate and frequency. The optimum condition was found at a CH4/O2 molar ratio of 3/1, a feed flowrate of 150 cm3/min and a frequency of 300 Hz for the maximum CH4 and O2 conversion with high synthesis gas selectivity and very low energy consumption. The energy consumption of the gliding arc system was found to be very low about 15.3-18.5 eV/molecule of CH4 converted as compared to 21 eV/molecule of CH4 converted for the corona discharge system with pin and plate electrodes.
