Enrichment of spent SF6 gas by zeolite membranes for direct reuse in gas-insulated switchgear units

Purification process for spent SF6 gas in gas-insulated switchgear (GIS) units. [Display omitted] •MFI and SAPO-34 zeolite membranes applied in spent SF6 gas purification.•A single zeolite membrane separation produced ultrapure SF6 gas (>99.7 %).•MFI membranes exhibited higher efficiency over SAPO-34 membranes in SF6 enrichment.•MFI membrane area of ∼ 0.09 m2 purified spent SF6 gas from GIS unit (145 kV in 6 h).•Compact SF6 enrichment systems with high separation and small footprint proposed. Zeolite membranes have attracted considerable attention in the separation industry owing to their high separation selectivity and permeance. However, their industrial applications have been hindered owing to a lack of case studies focusing on their commercialization. Herein, MFI and SAPO-34 zeolite membranes were employed to purify spent SF6 gas taken from a gas-insulated switchgear (GIS). This study demonstrated that separation by a single zeolite membrane produced ultrapure SF6 gas (>99.7 %) satisfying the reuse guidelines for GIS units. This level of purity is difficult to achieve using polymeric membranes due to the plasticization effect. The synthesized MFI membrane exhibited high N2 permeance with ∼ 2,000 gas permeation units (GPU) at 2 bar and low N2/SF6 selectivity (500) and relatively low permeance (