Design of metal-organic framework membranes towards ultimate gas separation

Metal-organic framework (MOF) membranes have shown unprecedented opportunities for energy efficient separation of diverse industrially important gas pairs (e.g. H2/CO2, CO2/N2, CO2/CH4, and C3H6/C3H8). Among the various factors, microstructure manipulation (including thickness, orientation, and grain boundary structure) and framework tuning (including pore size, framework rigidity/flexibility, and stimuli responsiveness) of MOF membranes have been found playing dominant roles in their separation performances. In this perspective, we highlighted some recent progress in polycrystalline MOF membranes with emphasis on the elucidation of the structure-performance relationship at different scales.