Experimental research and reaction process analysis of degradation of strong greenhouse gas SF₆ using 304 stainless steel

Emission reduction and substitution of sulfur hexafluoride (SF₆) is an important way to build a new type of green and low-carbon power platform system and to achieve the goal of “net-zero.” As a strong greenhouse gas widely used in the power industry, it is especially necessary to carry out harmless degradation treatment for SF₆ exhaust gas that cannot meet the reuse conditions. In this paper, based on thermal degradation treatment technology, 304 stainless steel was utilized to degrade SF₆. The study revealed that 304 stainless steel had a significant effect on the degradation of SF₆ gas. Particularly under low initial concentration (1700 ppm), low space velocity (1200–2400 mL/g₃₀₄·h), and high temperature (800 ℃) conditions, the currently designed SF₆ degradation platform could achieve a 100% degradation efficiency and maintain it for a long time. Simultaneously, the main gas phase products of the degradation reaction were detected as SO₂ and SiF₄, while the solid phase products were related to the initial concentration of SF₆. Under low concentration conditions, the solid phase products of the degradation reaction were FeF₂ and FeS, while under high concentration conditions, the degradation products were FeF₃ and S, the byproducts of Ni and Cr in 304 stainless steel were NiF₂ and CrF₃ respectively. Finally, the possible reaction pathways for 304 stainless steel to degrade SF₆ were determined, and the feasibility of the reaction was confirmed through thermodynamic calculations. This research provides valuable reference for the harmless degradation of SF₆ gas in the domestic and international power industry.