Novel Plasma Discharge Structure Driven Hydrogenation of CO2 at Room Temperatures and Atmospheric Pressure

A novel coaxial dielectric barrier discharge (DBD) reactor has been developed for plasma-driven CO2 hydrogenation at low temperatures and atmospheric pressure. Reverse water–gas shift reaction have been found dominant in the plasma CO2 hydrogenation process. The results demonstrated a significant influence of the auxiliary electrode on both the CO2 conversion rate and CO yield. This study aimed to investigate the impact of supported metal catalyst (Cu/γ-Al2O3) and auxiliary electrode on the hydrogenation performance of CO2. Compared to plasma-only CO2 hydrogenation without a catalyst, the combination of plasma with these catalysts resulted in a significant increase in the CO2 conversion rate ranging from 50.1% to 90.7%. Furthermore, when plasma was combined with an auxiliary electrode, an approximately eight-fold increase in the conversion rate was observed, attributed to a transition from filamentary discharge to arc discharge mode. Additionally, it was found that the CO2/H2 molar ratio significantly influenced both the conversion rate of CO2 and production of CO and CH4. Notably, integrating an auxiliary electrode with plasma enabled processing higher flow rates of CO2, achieving a yield of 63.92 ml/min at a flow rate of 250 ml/min for CO2.