CO₂Hydrogenation Using Nonthermal Plasma: Effects of Packed Beds on Plasma Discharge Behavior

Nonthermal plasma-assisted catalysis offers a promising approach to activate strong chemical bonds such as those in CO₂ and transform such stable molecules into value-added products under ambient conditions. Advancement in this field requires building upon understanding of plasma–catalyst interactions that dictate product selectivity, conversion, and energy efficiency. This study aims to systematically assess how different dielectric supports influence plasma discharge behavior and reactor performance during CO₂ hydrogenation in a dielectric barrier discharge reactor. The dielectric constant of the packing material strongly influences discharge behavior and, consequently, catalytic activity. Among the materials examined, Al₂O₃ exhibited the highest CO₂ conversion of 42% at a plasma power of 23 W, whereas CeO₂ yielded the lowest (∼5%) due to the formation of a diffuse discharge, in contrast to localized discharges or surface streamers. CO₂ conversion over CeO₂ beds of a given particle size were nearly identical irrespective of changes in particle size, further supporting this discharge-dependent behavior. Notably, this work highlights the importance of comparing reactor performance for packed beds under nonpartial discharge operation.