Investigation on Degradation Path of SF6 in Packed-Bed Plasma: Effect of Plasma-generated Radicals

Abstract

SF 6 degradation mechanism in non-thermal plasma (NTP) systems is not fully understood due to the formation of a complex physico-chemical reaction network, especially when reactive gases and packing materials are involved. In this work, we conduct a combined experimental and theoretical study to unravel the SF 6 degradation path in a γ-Al 2 O 3 packed plasma in the presence of H 2 O or O 2 . Our experimental results show that both H 2 O and O 2 have a synergetic effect with γ-A1 2 O 3 packing on promoting SF 6 degradation, leading to higher stable gas yields than typical spark or corona discharges. HO or O 2 addition promotes SO 2 or SO 2 F 2 selectivity, respectively. Density functional theory (DFT) calculations reveal that SO 2 generation corresponding with the highest activation barrier is the most critical step toward SF 6 degradation. Radicals like H and O generated from H 2 O or O 2 discharge can significantly promote the degradation process via Eley-Rideal mechanism, affecting key reactions of stable product generation, advancing degradation efficiency. The results of this work could provide insights on further understanding SF 6 degradation mechanism especially in packed-bed plasma systems.