Research progress on SF₆ emission reduction methods and separation recovery

A potent greenhouse gas, SF6 has a global warming potential far exceeding that of CO2. Further, its stability in the atmosphere renders it a persistent threat to the climate. Given the strong greenhouse effect and irreversible environmental accumulation characteristics of SF6, as well as China’s prominent position in the global emission pattern, SF6 emission reduction is an urgent concern for mitigating the greenhouse effect and achieving the “double carbon” goal. This paper describes three mainstream SF6 emission reduction methods, namely gas substitution, degradation treatment, and separation and recovery, and reviews the research status of various technologies. As compared to gas substitution and degradation treatment, separation and recovery method is effective in realizing the recovery and emission reduction of SF6 in waste electrical equipment. This technology combines the characteristics of gas substitution and degradation treatment, thereby avoiding environmental pollution and lowering the procurement cost of SF6. As it yields both environmental and economic benefits, separation and recovery is deemed a relatively feasible and comprehensive solution. However, no detailed literature review on SF6 separation and recovery methods has been reported, indicating a remarkable research gap in the area. Therefore, this paper focuses on the research progress of various separation and recovery methods for SF6, including low-temperature separation (low-temperature distillation, liquefaction, and low-temperature freezing), hydrate separation, adsorption separation, and membrane separation. The characteristics of various methods, including principle, cost, energy consumption, environmental impact, SF6 feed concentration, are comparatively analyzed. Finally, the development trend of SF6 separation and recovery is outlined. While various separation and recovery methods have been proposed, certain limitations have been identified. Accordingly, integration and optimization of materials, processes, and systems; coordination of multiple separation and recovery methods; and comprehensive evaluation and policy implementation of SF6 separation and recovery are key research directions. The development of SF6 separation and recycling technology must focus on the following three aspects: material optimization, technology collaboration, and policy evaluation. At the material level, challenges such as the plasticization of membrane materials, capacity limitation of adsorbents, and trade-off between selectivity and permeability must be addressed. Further, the thermodynamic conditions of low-temperature separation equipment (e.g., high-efficiency compressors and multi-stage separators) and hydrate method must be optimized. As regards technical synergy, reliance on a single method is constrained by energy consumption or efficiency bottlenecks. Therefore, coupling approaches, such as membrane separation–low-temperature condensation separation systems, pressure swing adsorption–liquefaction co-generation systems, and hydrate–liquefaction processes, must be promoted to improve recovery efficiency through complementarity. Systematic evaluation must be employed to quantify energy consumption, cost, purity and recovery rate, establishing a comprehensive evaluation system for technology and economy. At the policy level, the government should formulate incentive policies and life-cycle supervision mechanisms to promote technological iteration and application. In the future, the integration and innovation of materials, processes, and systems, combined with multi-technology incorporation, policy-driven measures, and iterative material advancement, would be essential to achieve high-efficiency, environment-friendly, and economically viable SF6 separation and recycling.