Research progress on SF6 emission reduction methods and separation recovery

As a potent greenhouse gas, SF6 has a global warming potential far exceeding that of carbon dioxide, and it is difficult to decompose in the atmosphere, posing a lasting threat to climate change. In view of its strong greenhouse effect, irreversible environmental accumulation characteristics and China's prominent position in the global emission pattern, promoting SF6 emission reduction is an urgent need to alleviate the greenhouse effect to achieve the "double carbon" goal. In this paper, three mainstream SF6 emission reduction methods, namely gas substitution, degradation treatment, and separation and recovery, are described, and the research status of various technologies is reviewed. Compared with the two ways of substitution gas and degradation treatment, separation and recovery is an effective way to realize the recovery and emission reduction of SF6 in waste electrical equipment, and the separation and recovery technology combines the characteristics of alternative gas and degradation treatment, which not only avoids environmental pollution, but also reduces the procurement cost of SF6, and has both environmental and economic benefits, which is a more feasible and comprehensive solution. However, there is no detailed literature summary on SF6 separation and recovery methods, so there is a gap in the research direction of SF6 separation and recovery. Therefore, this paper focuses on the research progress of various separation and recovery of SF6, including low-temperature separation (low-temperature distillation, liquefaction, low-temperature freezing), hydrate separation, adsorption separation, and membrane separation, and compares and analyzes the characteristics of various methods, including principle, cost, energy consumption, environmental impact, SF6 feed concentration, etc. Finally, the development trend is proposed: there are still some limitations in various separation and recovery methods, and the integration and optimization of materials, processes and systems, the coordination of multiple separation and recovery methods, and the comprehensive evaluation and policy implementation of separation and recovery are the potential development directions of separation and recovery SF6 technology. The development of SF6 separation and recycling technology needs to focus on three aspects: material optimization, technology collaboration and policy evaluation. At the material level, it is necessary to solve the plasticization of membrane materials, the capacity limitation of adsorbents, and the contradiction between selectivity and permeability, and optimize the thermodynamic conditions of low-temperature separation equipment (such as high-efficiency compressors and multi-stage separators) and hydrate method. In terms of technical synergy, a single method is constrained by energy consumption or efficiency bottlenecks, and it is necessary to couple membrane separation-low-temperature condensation separation system, PSA-liquefaction co-generation system, and hydrate-liquefaction process to improve recovery efficiency through complementarity. Systematic evaluation needs to quantify energy consumption, cost, purity and recovery rate, and build 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 technology iteration and application. In the future, it is necessary to strengthen the integration and innovation of materials, process and system, combine multi-technology integration and policy-driven, and cooperate with the iterative update of materials to achieve high efficiency, environmental protection and economy of SF6 separation and recycling.