SF 6 catalytic degradation in a γ‐Al 2 O 3 packed bed plasma system: A combined experimental and theoretical study

Abstract Effective abatement of the greenhouse gas sulphur hexafluoride (SF 6 ) waste is of great importance for the environment protection. This work investigates the size effect and the surface properties of γ‐Al 2 O 3 pellets on SF 6 degradation in a packed bed dielectric barrier discharge (PB‐DBD) system. Experimental results show that decreasing the packing size improves the filamentary discharges and promotes the ignition and the maintenance of plasma, enhancing the degradation performance at low input powers. However, too small packing pellets decrease the gas residence time and reduce the degradation efficiency, especially for the input power beyond 80 W. Besides, lowering the packing size promotes the generation of SO 2 , while reduces the yields of S‐O‐F products, corresponding to a better degradation. After the discharge, the pellet surface becomes smoother with the appearance of S and F elements. Density functional theory calculations show that SF 6 is likely to be adsorbed at the Al III site over the γ‐Al 2 O 3 (110) surface, and it is much more easily to decompose than in the gas phase. The fluorine gaseous products can decompose and stably adsorb on the pellet surface to change the surface element composition. This work provides a better understanding of SF 6 degradation in a PB‐DBD system.