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

Abstract

ABSTRACT 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.