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 C 2 H 4 /C 2 H 6 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 C 2 H 4 selectivity due to the optimized diffusion path. The Ni-pca-pyz membrane with preferential (001) crystal plane orientation shows highly competitive C 2 H 4 /C 2 H 6 separation performance, with a C 2 H 4 permeance of 351.2 GPU and a C 2 H 4 /C 2 H 6 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.