Effective abatement of the greenhouse gas sulphur hexafluoride (SF₆) waste is of great importance for the environment protection. This work investigates the size effect and the surface properties of γ-Al₂O₃ pellets on SF₆ 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 SO₂, 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 SF₆ is likely to be adsorbed at the Al_III site over the γ-Al₂O₃(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 SF₆ degradation in a PB-DBD system.

中文翻译：

---

γ-Al2O3 填充床等离子体系统中的 SF6 催化降解：实验和理论相结合的研究

温室气体六氟化硫(SF ₆ )废物的有效减排对环境保护具有重要意义。这项工作研究了 γ-Al ₂ O ₃颗粒对填充床介质阻挡放电 (PB-DBD) 系统中SF _{6降解的尺寸效应和表面特性。}实验结果表明，减小填料尺寸可改善丝状放电并促进等离子体的点火和维持，从而增强低输入功率下的降解性能。然而，过小的填料颗粒会减少气体停留时间并降低降解效率，特别是对于超过 80 W 的输入功率。此外，减小填料尺寸会促进 SO _2的产生，同时降低了 SOF 产品的产量，对应于更好的降解。放电后，颗粒表面变得更光滑，并出现S和F元素。密度泛函理论计算表明SF ₆很可能被吸附在γ-Al ₂ O _{3 (110)表面的Al III}位点，并且比在气相中更容易分解。氟气态产物可以分解并稳定地吸附在颗粒表面，改变表面元素组成。这项工作有助于更好地了解 PB-DBD 系统中的 SF ₆降解。