Effect of ZnO/γ-Al2O3 Catalyst Packing on the Degradation of SF6 in a Dual-Stage DBD Plasma Reactor.

Sulfur hexafluoride (SF6) gas is widely used in the electric power industry as an excellent insulating gas. However, SF6 is a potent greenhouse gas, and its degradation is an ideal method for emission reduction. In the field of SF6 degradation, due to the harsh decomposition conditions, it is often difficult to achieve both a high degradation rate and favorable product distribution. To address this issue, a double-stage dielectric barrier discharge (DBD) series degradation experimental platform for SF6 gas was designed in this study. A ZnO catalyst was packed in the first-stage reactor to improve the SF6 degradation rate, while a γ-Al2O3 catalyst was packed in the second-stage reactor to optimize the product distribution. Additionally, the selectivity of SF6 degradation products was regulated by externally adding H2O. Experimental results showed that under an input power of 100 W, the SF6 degradation rate reached 100% in the ZnO/γ-Al2O3 double-stage packed system, achieving complete degradation of SF6. As the input power increased, the energy yield showed a gradually decreasing trend. The addition of an appropriate concentration of H2O effectively improved both the degradation rate and energy yield of SF6, with the maximum energy yields of the two-stage reactors reaching 23.9 and 17.9 g/kWh, respectively. With regard to decomposition products, the types of SF6 decomposition products in both reactors remained unchanged, including SO2, SO2F2, SOF2, and SOF4. The main product in the first-stage reactor was SO2F2, whereas in the second-stage reactor, SO2 was predominant. The addition of H2O also effectively increased the yield of SO2 while suppressing the formation of SO2F2, which is more difficult to treat. This study provides experimental support for SF6 exhaust gas degradation and offers a research direction for industrial applications.