Experimental study of temperature management on CO2 decomposition in a planar dielectric barrier discharge reactor

In this paper, a new attempt for improving CO2 decomposition in a dielectric barrier discharge (DBD) reactor is proposed from the aspect of regulating the inlet CO2 gas temperature and the plasma discharge zone temperature. Meanwhile, a comparative study is conducted under three cases of no cooling, the use of gas precooling, and the combination of gas precooling and bare electrode cooling. The experimental results show that the introduction of gas precooling can nearly double CO2 conversion, while the introduction of bare electrode cooling in the presence of gas precooling only leads to an increase of about 10% in CO2 conversion. With the combined use of gas precooling and bare electrode cooling, the highest CO2 conversion of 47% is obtained at a CO2 flow rate of 20 sccm. Further analysis of discharge characteristics indicates that gas precooling results in a considerable enhancement of the reduced electric field in plasma filaments, while the bare electrode cooling enhances the reduced electric field slightly. It is inferred that the two kinds of cooling could enhance the electron impact dissociation in plasma filaments and suppress the three-body recombination process in the entire discharge zone, which leads to different degrees of improvement on CO2 decomposition. The work provides a reference for controlling the temperature of chemical reactions in atmospheric DBD.