577 / 2022-03-30 14:31:55

Plasma-assisted abatement of SF6 in a γ-Al2O3 packed bed DBD system: A combined experimental and theoretical study

non-thermal atmospheric plasma,DBD,SF6,degradation,γ-Al2O3

Purpose/Aim

Efficient degradation of sulfur hexafluoride (SF₆) is an important approach to reduce its emission in power industry. This work investigates the size effect and the surface properties of γ-Al₂O₃ packing on SF₆ degradation in a DBD system.

Experimental/Modeling methods

A double coaxial quartz tube packed by 1~4 mm γ-Al₂O₃ is used for SF₆ degradation experiment and density functional theory (DFT) calculation is applied to analyze how the SF₆ adsorbs and decomposes on the γ-Al₂O₃ pellet surface and the formation of surface fluorine species.

Results/discussion

Experimental results show that decreasing the packing size improves the filamentary discharges and the degradation performance. Too small packing pellets decreases the gas residence time and reduces the degradation efficiency. Besides, lowering the packing size promotes the generation of SO₂, while reduces the yields of S-O-F products. DFT calculations show that SF₆ can be adsorbed at the Al_Ⅲ site on the γ-Al₂O₃(110) surface and decompose much more easily than in the gas phase. The fluorine gaseous products is likely to decompose and stably adsorb on the γ-Al₂O₃ surface, thus to change the surface element composition.

Conclusions

γ-Al₂O₃ pellets have a catalytic effect for SF₆ activation and decomposition. The size of γ-Al₂O₃ pellets is an important factor in determining the degradation efficacy and product selectivity.

Appendix