Synergistic effect of catalyst and plasma on CO2 decomposition in a dielectric barrier discharge plasma reactor

Abstract

Plasma has been widely used in wastewater treatment, material modification and biomedicine due to its unique properties. In this work, a coaxial cylindrical dielectric barrier discharge (DBD) reactor was set up to investigate the effects of electrode materials and catalyst combined with DBD plasma on CO2 decomposition under room temperature and atmosphere pressure. The materials of inner electrode and outer electrode were investigated without catalysts packed in the reactor. It was found that the aluminum rod as inner electrode performed better than copper rod and stainless steel rod due to the moderate thermal conductivity and electrical conductivity of aluminum rod. Nevertheless, copper foil worked better as external electrode material since its higher electrical conductivity facilitated generation of high energy electrons by the high voltage between electrodes. After perovskite-type catalyst was introduced in the reactor, CO2 conversion increased, which was attributed to the synergistic effect of perovskite combined with plasma discharge. Perovskite-type catalysts could modulate the capacitance of the reactor to make plasma discharge more uniform and increased CO2 conversion, while plasma discharge provided high energy electrons that activated oxides sites and basic sites of perovskite-type catalysts. The maximum CO2 conversion was 23 % and maximum energy efficiency was 2.1 % when MgTiO3 was packed in the reactor.