CO<inf>2</inf> dissociation using the versatile atmospheric dielectric barrier discharge experiment (VADER)

Abstract

To determine the viability of dielectric barrier discharges (DBDs) for CO 2 dissociation and other highly endothermic reactions, we developed a DBD-relevant chemical model for CO 2 dissociation and constructed a new DBD apparatus. The chemical model compares the chemical reaction rates during the different stages of a DBD discharge to determine which reactions control the chemical kinetics of a CO 2 plasma. The model showed that during the breakdown/cascade phase of the DBD electron impact dissociation, electron attachment and electron vibrational excitation are the dominant reactions within the plasma. However, relaxation of the dissociated components within the discharge afterglow determines the final chemical state of the system. The model also showed that the relaxation path taken is highly dependent on the gas temperature and the amount of product gas built up in the system. VADER is a planar DBD experiment used to determine the effects of different system parameters on the dissociation of CO 2 . These experiments showed that CO 2 dissociation efficiencies and rates are highly affected by multiple parameters including the power supply driving frequency (the most efficient dissociation occurs at a resonant frequency determined by the chemical kinetics), the gas composition (efficiency and rate improved with the addition of argon) and the addition of a photocatalyst into the reaction chamber (a photocatalyst improved CO 2 dissociation efficiencies and rates in a plasma operating at higher driving frequencies). ________________________________ *

CO2dissociation using the Versatile atmospheric dielectric barrier discharge experiment (VADER)

“…Longer pathways require larger energy input, which take energy away from dissociative processes and increase the need for energy recuperation. The majority of these higher energy dissociative pathways in a CO 2 plasma come from radical chemistry and ionization processes, for instance oxygen (O) relaxation; CO + 2 , CO + , and O + ionization and recombination; and charge exchange [6].…”

“…In general, higher potentials across the air gap and low ionization energy gases lead to higher streamer densities. A detailed description of streamer dynamics is given in Lindon [6].…”

“…The relevant electron-CO 2 collision reactions and their corresponding cross-sections are tabulated in Lindon [6]. The cross-sections were obtained from Itikawa [12], Anzai et al [27], Seiersen et al [28], McConkey et al [15], Itikawa [29], Peverall et al [30], Sheehan and St Maurice [31], Rosén et al [32], Rapp and Briglia [33], Schulz [34], Zecca et al [35], Rejoub et al [36], Derai et al [37], Flesch and Ng [38], and Flesch et al [39].…”

“…The detailed design is described within Lindon [6]. VADER is a planar DBD at the center of a 20.32 cm Lesker 6 way CF cross.…”

“…The results include the CO 2 dissociation efficiencies, dissociation rates and the different variables that affect efficiency. For full details about the models and experiments, see Lindon [6].…”