Effect of High Voltage Electrode Material on Methanol Synthesis in a Pulsed Dielectric Barrier Discharge Plasma Reactor

Plasma methanol synthesis from captured CO2 and renewable H2 is one of the most promising technologies that can drastically lower the carbon footprint in methanol production, but the associated high energy costs make it less competitive. Herein, we investigated the impact of the high-voltage electrode configuration on methanol formation. The effect of electrode materials Cu, Al, and stainless steel (SS) SUS304 on CO2 hydrogenation to methanol using a temperature-controlled pulsed dielectric barrier discharge (DBD) plasma reactor was examined. The electrode surface area (ESA) was varied from 157 mm2 to 628 mm2 to determine the effect on discharge characteristics and the overall influence of plasma surface reactions on methanol production. The Cu electrode showed superior methanol synthesis performance (0.14 mmol/kWh) which was attributed to its catalytic activity function, while the Al electrode had the least production (0.08 mmol/kWh) ascribed to the excessive oxide coating on its surface, passivating its ability to promote methanol synthesis chemical reactions. In all electrode materials, the highest methanol production was achieved at 157 mm2 ESA at a constant applied voltage. Lastly, the plasma charge concentration per discharge volume was determined to be an important parameter in fine-tuning the DBD reactor to enhance methanol synthesis.