Spatio-Selective Reconfiguration for Enhanced Ethylene/Ethane Separation in Metal–Organic Framework Membranes

Due to the similar kinetic diameters and physicochemical properties of ethylene and ethane, developing highly efficient C2H4/C2H6 separation membranes remains a huge challenge. In this study, spatio-selective reconfiguration of a Ni-pca-pyz metal–organic framework (MOF) membrane was discovered upon vacuum heat treatment. The progressive migration of the low-boiling-point pyrazine ligands on the coordination unsaturated metal sites in the structure can result in the preferential exposure of the (001) crystal plane, thus the significant increase in C2H4 selectivity due to the optimized diffusion path. The Ni-pca-pyz membrane with preferential (001) crystal plane orientation shows highly competitive C2H4/C2H6 separation performance, with a C2H4 permeance of 351.2 GPU and a C2H4/C2H6 separation factor of 5.6 during mixed-gas permeation, highlighting the promising application of the vacuum heat treatment protocol in structure optimization and performance enhancement of versatile MOF membranes.