CO2 conversion characteristics by micro-gap DBD plasma reactor
Yukio Hayakawa*, Primas Emeraldi, Tsutomu Imai, Shinji Kambara
* The author to whom correspondence should be addressed.
Environmental and Renewable Energy System Division, Graduate School of Engineering, Gifu University, Japan
Abstract
CO2 conversion into CO and O2 using dielectric barrier discharge (DBD) reactors suffers from a low conversion and energy efficiency. Therefore, proper tuning of plasma processing parameters and modification of DBD reactor design is needed to enhance the CO2 conversion performance. This study investigated the combined effect of micro-gap discharge and pulsed power on the CO2 conversion performance of the pure CO2 splitting process. The CO2 conversion, energy efficiency and CO selectivity were evaluated at various discharge power and gas flow rate. Moreover, the electrical characterization was performed to evaluate the effect of these processing parameters on the plasma regime of the pulsed micro-gap DBD reactor. The findings indicate that the CO2 conversion and streamer intensity were significantly influenced by gas flow rate, while the energy efficiency and discharge regime were greatly affected by discharge power. All the decomposed CO2 was also decomposed into CO and O2. The maximum CO2 conversion of 51.42% was obtained at an SEI of 154.74 kJ L-1 with a corresponding energy efficiency of 4.15%. On the other hand, the highest energy efficiency of 9.43% was achieved at an SEI of 25.26 kJ L-1 with a corresponding CO2 conversion of 4.15%. Most of the decomposed CO2 was converted to CO and O2, but small amounts of carbon precipitation were also observed under low flow conditions. These results suggest that the pulsed micro-gap DBD might be more favorable than the DBD reactor with expensive packing material for industrial application.
Keywords - Non-thermal plasma, CO2 conversion, dielectric barrier discharge, micro-gap reactor.