CO₂ plasma in fluidized bed—DC glow discharge reactor

Abstract

Plasma-catalysis holds great potential for efficient CO2 recycling but the effectiveness of this approach depends on how plasma sources and catalytic materials are coupled. Fluidized bed (FB) reactors are interesting because they exhibit increased surface contact area between material particles and gas phase, and improved heat transfer. A low-pressure DC glow discharge (GD) in FB configuration, ignited with or without fluidized Al2O3 particles, is investigated with optical emission spectroscopy. A decrease in oxygen atom density through the fluidization of the material and an increase in the intensity of CO systems, attributed to increased CO density and to a lesser extend to electric field changes, is observed in comparison to the plasma alone. This indicates that fluidized particles indeed cause a reduction in the O presence leading to an increase in CO density. The rotational temperature does not significantly change, despite the more efficient heat transfer to the wall expected in FB-GDs. This is attributed to the higher current density induced by the confinement of the plasma in the center of the tube by the charged particles. The plasma-assisted catalytic behavior is further investigated by infrared absorption spectroscopy downstream of the FB-GD, showing superior conversion performance compared to the GD alone. The development of this innovative route is crucial to understanding the enhancement of plasma-surface interaction for CO2 recycling.