Dielectric barrier discharge coupled with oxygen-vacancy-rich NiO-CeO2 for efficient and low-energy degradation of SF6

How to achieve low energy consumption and high degradation efficiency (DRE) under mild conditions is an important issue in the field of sulfur hexafluoride (SF6) treatment. In this work, a new route of SF6 degradation promoted by Ni-doped ceria (NiO−CeO2) in a packed bed dielectric barrier discharge (PB-DBD) was proposed. The effects of Ni/Ce molar ratio, input power, SF6 concentration and flow rate on the DRE of SF6 were investigated. Compared with DBD or CeO2-DBD alone, the combination of DBD and NiO−CeO2 can significantly promote the SF6 degradation at lower input power. The experimental results show that when the dosage of catalyst 1.5NiO-CeO2 (Ni/Ce mole ratio is 1.5%) is 5 g, DBD input power is 50 W and SF6 (1.5% SF6/98.5% Ar) flow rate is 100 ml·min−1, the highest DRE can reach 97.7% and the energy yield can reach 11.5 g·(kW·h)−1. Adjusting the catalyst dosage according to the flux of SF6 (e.g., using 10 g catalyst to degrade SF6 with a concentration of 1.5% and a flow rate of 80 ml·min−1), the DRE of nearly 99% can be achieved for a long time, which is crucial for industrial application. The mechanism deduction shows that the rich surface and mesopores of the catalyst are beneficial to the adsorption of SF6 and intermediates, while the doping of Ni can significantly increase the content of oxygen vacancies to improve the degradation. Meanwhile, when NiO−CeO2 is activated by DBD, the free O· can further promote the degradation. It is this coupling effect that leads to the high efficiency and low energy consumption of SF6 degradation under mild conditions. It can be expected that this coupling technology route will have a good application prospect in the field of SF6 treatment.