CO2 conversion in a coaxial dielectric barrier discharge plasma reactor in the presence of mixed ZrO2-CeO2

Dielectric barrier discharge (DBD) plasma in packed bed reactors are widely used in the environment and energy (such as CO2 conversion). Packing material is a key factor in the reaction of splitting CO2 into CO and O2 by dielectric barrier discharge plasma. To get higher CO2 conversion, grinding balls made of a mixture of ZrO2 and CeO2 in a certain proportion was employed as packing material in this work. The effects of discharge power, feed flow rate, packing length, circulating water temperature and particle size on discharge characteristics and CO2 conversion were investigated to have a better understanding of the performance of the packing material. The reactor discharge behavior was observed by determining the product gas composition and plasma power consumption to determine CO2 conversion and energy efficiency. The packing of the catalyst in the reactor makes the discharge mode from the initial filament discharge to the combination of filament discharge and surface discharge. Compared with oxides composed of a single substance, the two oxides of the composite catalyst can interact, possibly achieving a synergistic effect. Typical results showed that this mixed material had a better property than the reported materials like BaTiO3, Al2O3, ZrO2 and so on which consist of a single substance. The maximum CO2 conversion reached 64.38 % and the maximum energy efficiency reached 8.76 %, which is currently the highest in the known literature. The higher circulating water temperature and larger particle size lead to the decrease of CO2 conversion and energy efficiency. The best performance of the mixture catalyst may be attributed to the oxygen vacancies, which stabilizes the atomic oxygen produced in the reaction and thus facilitates the conversion of CO2.