Influence of Operating Parameters on Plasma-Assisted Dry Reforming of Methane in a Rotating Gliding Arc Reactor

The environmental impact of greenhouse gases such as carbon dioxide and methane can be reduced if they are used as feedstock to synthesize chemical building blocks such as syngas (CO, H-2) via dry reforming. Methane dry reforming is investigated using an Ar/CO2/CH4 rotating gliding arc (RGA) reactor powered by a dual-stage pulsed DC power supply. Tangential gas injection combined with a static magnetic field enabled the rotation and upward displacement of the arc along the conical cathode and the grounded anode, yielding to a larger plasma volume. Different parameters such as peak arc current (0.74 and 1.50 A), total gas flow rate (3.7, 4.7 and 6.7 SLPM), CO2/CH4 ratio (1.0, 1.5, 2.0) and gas inlet preheating (room temperature, 200 degrees C) were studied to determine the most efficient parameter combination. Gas conversion was measured online using a calibrated mass spectrometer and offline using a gas chromatograph. Noticeable increases in CO2 and CH4 conversions, as well as H-2 and CO yields, were obtained when doubling the peak arc current. For the larger peak current, higher H-2 yields were obtained at a CO2/CH4 = 1.0, and the best energy efficiencies were obtained at the lowest specific energy input values. No significant effect of the gas inlet temperature on the conversions or yields was found. Trace amounts of acetylene and ethylene, as well as some carbon deposits were observed as by-products of syngas generation. The low amount of by-products obtained implies a good selectivity for CO and H-2, i.e., a cleaner syngas when produced with RGA discharge.