Speakers

Biography

Riley Yager has been working with Dr. Stanishevsky at the University of Birmingham at Alabama on ceramic nanofibrous materials and their catalytic properties.  Her research has sent her to the technical universities in Lodz, Poland, and Liberec, Czech Republic, where she gained hands-on experience in international laboratories and built meaningful collaborations.  She also had the opportunity to work in Lodz, Poland, under the Fulbright program during the 2021-2022 academic year.  Her research is supported by the NASA Space Technology Graduate Research Opportunities (NSTGRO22) program where she works with DBD plasmas for the purpose of converting CO2 into oxygen under Martian atmospheres for future goals in terraforming.

Abstract

The effects of greenhouse gas emissions on the Earth’s atmosphere and temperature have become an increasingly pressing issue in recent years.  The capture and conversion of these gases are crucial in order to avoid the catastrophic consequences of global warming.  Current technologies for these conversions have encountered many obstacles including the high thermodynamic stability of CO₂ and the fast deactivation of CH₄.  The high energy cost and scalability of these processes also pose significant challenges in development.  Non-thermal plasmas (NTPs), with a mean energy of 1-10 eV, have the potential to activate and dissociate ground-state gas molecules and allow reactions to occur at relatively low temperatures and atmospheric pressure.  NTPs have been shown to break the strong chemical bonds of the CO₂ molecule without the presence of a catalyst as well as activate and convert CH₄ into higher hydrocarbons.  However, due to the probabilistic nature of NTPs, the selectivity of desired products is poor due to unselective collisions between the active species.  Therefore, it is necessary to explore different plasma catalytic systems in order to improve selectivity.  In this investigation, different configurations of dielectric barrier discharge (DBD) plasma reactors were tested with carbon dioxide and methane at reduced pressures.  Various electrical parameters including frequency and voltage were manipulated as well as the supplied gas flow and reactor chamber pressure.  This presentation demonstrates an intensive study of the effects of these process parameters on plasma behavior and species.  Optical emission spectroscopy (OES) was utilized to observe the species produced within the plasma region at different locations within the reactor.  It was found that varying the pressure in the reactor chamber to various sub-atmospheric pressures had the most significant effect on the plasma and conversion of CO₂ and CH₄.  The dissociation of CO₂ is heavily dependent on the electrode configuration producing either CO and atomic oxygen species or O₂ and a pure carbon residue.  Plasma interactions with CH₄ showed the production of significant amounts of H₂ confirming the successful activation of methane within the plasma region.