Synergistic CO2 conversion by hybridization of dielectric barrier discharge and solid oxide electrolyser cell

Abstract

Hybrid reactor of Dielectric Barrier Discharge (DBD) and Solid Oxide Electrolyser Cell (SOEC) was fabricated and CO2 decomposition characteristics were investigated. For the case of the DBD reactor alone, the CO2 conversion saturates with residence time. In contrast, the saturation is not observed for the case of the hybrid system where CO2 conversion increases monotonically with increasing residence time. This is because the reverse reaction to regenerate the CO2 in plasma is suppressed by the oxygen removal by SOEC in hybrid system and consequently CO2 decomposition reaction proceeds irreversibly. We have examined the experimental results by analytical modeling and reaction mechanism for the CO2 decomposition in the hybrid reactor of DBD and SOEC is deduced. The time‐dependent CO2 conversion for the only plasma reactor and hybrid reactor can be reproduced by a reversible and irreversible first‐order reaction model, respectively. The analytical model can also reproduce the dependence of CO2 conversion on the plasma input power very well. Interestingly, not only the reverse reaction rate but also the forward dissociation reaction rate is reduced by the SOEC in the case of hybrid reactor. The analytical modeling suggests that CO2 decomposition in the conventional DBD plasma reactor proceeds not merely by direct electron impact dissociation but also by reaction with reactive oxygen.