Characteristics of carbon dioxide reforming of methane via alternating current (AC) corona plasma reactions

Carbon dioxide reforming of methane via plasma reactions has the double advantage of realizing energy conversion and protecting the environment. We studied the characteristics of AC corona plasma CO2-reforming reactions at atmospheric pressure. The effects of the CH4/CO2 ratios in the feeds, discharge power, and flow rates were investigated. The H-2/CO ratios in the products mainly depended upon the CH4/CO2 ratios, and they increased from 0.21 at 0.2 CH4/CO2 to 2.15 at 2.0 CH4/CO2. The conversions of CH4 and CO2 increased with increasing discharge power, whereas they decreased with increasing flow rates. Within the tested range, the conversions of CH4 changed from 67.5 to 90.5% and the conversions of CO2 changed from 45.7 to 78.5%. The conversions obtained in the reactor below 380 K were higher than the calculated data, resulting from equilibrium thermodynamics at 890 K. Comparing the experimental results with the calculated values, we speculate that corona plasma possibly has a high-temperature character and that the plasma reactions possess an inherent quenching mechanism; i.e., the gases were rapidly cooled as they flowed out of the corona plasma area. This quenching mechanism resulted in the corona plasma reactions possessing higher conversions. The H-2/CO ratios in the products could be used to support this hypothesis.