Non-thermal plasma upgrading of humidified CO2 into syngas in a dielectric barrier discharge reactor: tuning H2/CO ratios via specific energy input and gas flow rate

Abstract

This study investigates the non-thermal plasma (NTP)-driven conversion of humidified CO₂ into syngas (H₂:CO:CO₂) using a dielectric barrier discharge (DBD) reactor. NTP enables CO₂ and H₂O dissociation at near-ambient conditions through high-energy electron collisions, eliminating the need for thermal input or expensive catalysts. While prior studies have examined gas composition and humidity effects, the influence of specific energy input (SEI) and gas flow rate on syngas yield and energy efficiency remains underexplored. Here, we systematically evaluate the relationship between SEI, flow rate, energy efficiency, and H₂/CO composition. Experiments conducted in a coaxial DBD reactor demonstrate syngas generation with tunable H₂/CO ratios ranging from 0.1 to 0.2 with energy efficiencies ranging from 4.5 to 23.3%. Results indicate that higher flow rates enhance energy efficiency, while increasing SEI leads to a plateau in CO and H₂ production, suggesting limits in energy transfer efficiency. Overall, these findings can inform the design of next-generation NTP systems towards a circular carbon economy.