Dry reforming of methane in a rotating gliding arc plasma: Improving efficiency and syngas cost by quenching product gas

Abstract

Rotating gliding arc (GA) plasma has attracted increasing interest in dry reforming of methane (DRM) for CO2 utilization. Most DRM studies using GA plasma are conducted to improve energy efficiency by increasing the conversion of reactants. This study aimed to improve energy efficiency by increasing the selectivity of products, particularly that of H2. To increase the selectivity of H2, a quenching device (i.e., a quenching rod (QR)) was developed to protect H2 from being consumed by suppressing the reverse water–gas shift (RWGS) reaction that is dominant in CO2 and H2 consumption in DRM processes. When the QR was applied, the conversion of CH4 and CO2 was reduced, while the selectivity and yield of H2 and H2O changed significantly, i.e., the yield of H2 increased, and the yield of H2O decreased. Owing to the increased yield of H2, the energy efficiency and syngas cost were improved. At an SEI of 4.2 kJ/L with a CH4/CO2 ratio of 5/7, the conversion of CH4 and CO2 was 51.1% and 40.2%, respectively; the highest energy efficiency was 55.3% with syngas costs of 10.9 kJ/L. Moreover, compared with the results of other DRM studies, syngas with the highest H2/CO ratios of 0.95 and 1.26 at CH4/CO2 ratios of 5/7 and 1 was produced with the reactor applied in this study, respectively. In conclusion, optimizing the quenching process will probably further improve the DRM performance. Moreover, the quenching method will be applied to dry reforming processes for syngas with high H2/CO ratios.