Industrial productions need the separation processes, but they are quite energy intensive, which occupy about half of the total energy consumption. Membrane technology based on a non-thermal route is expected to reduce the associated energy duties by ~90%, but effective membrane materials capable of precisely isolating targeted species from complex mixtures are highly needed. Metal-organic frameworks (MOFs), possessing the tuneable pore size and geometry, are regarded as the promising platform for molecular separations and membrane design. 

This dissertation illustrates the rational design and the guided fabrication for various MOF membranes. Respectively, different gas separation applications were addressed by using these membranes, such as light hydrocarbon separations, carbon dioxide (CO2) captures and natural gas purifications. A versatile strategy for membrane fabrication is developed based on the electrochemical method. Following this, a family of face-centered cubic (fcu) MOF membranes were obtained, which possess different ligands and different clusters, namely rare-earth hexanuclear or zirconium hexanuclear clusters. Two MOF membranes based on fumarate (fum) linker, Zr-fum-fcu-MOF and Y-fum-fcu-MOF, showed efficient separation for the propylene/propane binary mixture, as well as the butane/isobutane equimolar mixtures, respectively. Further aperture editing applied to Zr-fum-fcu-MOF via mixed-linker approach permits the introduction of shape irregularity to the parent trefoil-shaped apertures, inducing an ideal shape-mismatch with tetrahedral CH4 molecules and blocking their transportation while affecting linear molecules slightly such as nitrogen (N2) and CO2. The resultant Zr-fum67-mesaconate (mes)33-MOF membranes exhibit great promise for natural gas purification, including efficient nitrogen rejection and simultaneous removal of CO2 and N2 from natural gas.