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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> dissociation and other highly endothermic reactions, we developed a DBD-relevant chemical model for CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . These experiments showed that CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> dissociation efficiencies and rates in a plasma operating at higher driving frequencies).