A High-Performance N-Selective MXene Membrane with Double Selectivity Mechanism for N/CH Separation.

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