Synergistic Decomposition of CO2 by Hybridization of a Dielectric Barrier Discharge Reactor and a Solid Oxide Electrolyser Cell

In order to enhance the CO2 decomposition efficiency of plasma chemical reactions, a hybrid reactor consisting of a dielectric barrier discharge (DBD) reactor and a solid oxide electrolyzer cell (SOEC) was fabricated. The SOEC, composed of a yttria-stabilized zirconia (YSZ) tube (electrolyte: o.d. is 15 mm and thickness is 2 mm) with lanthanum strontium manganite (LSM) thin films (electrodes), was inserted into a quartz tube of 18 mm in inner diameter. The outer surface of the quartz tube was wrapped with SUS mesh, which was connected to a high voltage supply. CO2 was fed into the space between the quartz tube and the SOEC where the dielectric barrier discharge was formed. The composition of product gas was analyzed by gas chromatography. The inside of the SOEC was evacuated with a rotary pump in order to enhance desorption of permeated oxygen. When the permeation current of the SOEC was high enough to remove the oxygen from the CO2 plasma region completely, the synergistic effect of the hybridization became apparent, and CO2 conversion increased rapidly with increasing SOEC permeation current. When the plasma reactor and SOEC were operated independently, the maximum CO2 conversions were 40% for the DBD plasma reactor and 6% for the SOEC. However, the maximum CO2 conversion by the hybrid reactor was about 80%, much higher than the sum of the conversions of the plasma reactor and the SOEC. Possible reasons are discussed for the synergistic effect of hybridization of the DBD reactor and the SOEC on the CO2 decomposition.