A High-Performance N₂-Selective MXene Membrane with Double Selectivity Mechanism for N₂/CH₄ Separation

Membrane-based separation process for unconventional natural gas purification (mainly N₂/CH₄ separation) has attracted more attention due to its considerable economic benefits. However, the majority of separation membranes at this stage, particularly N₂-selective membranes, achieve the desired separation target by mainly relying on the diffusivity-selectivity mechanism. To overcome the limitation of a single mechanism, 2D lamellar MXene membranes with a double selectivity mechanism are prepared to enhance N₂ permeance and N₂/CH₄ selectivity via introducing unsaturated metal sites into MXene, which can form specific interactions with N₂ molecules and enhance N₂ permeation. The resulting membranes exhibit an inspiring N₂/CH₄ separation performance with an N₂ permeance of 344 GPU and N₂/CH₄ selectivity of 13.76. The collaboration of the double selectivity mechanism provides a new idea for the development of a novel N₂-selective membrane for N₂ removal and CH₄ purification, which further broadens the application prospects of membrane separation technology in the field of unconventional natural gas purification.