Mixed Matrix Membranes with Surface Functionalized Metal–Organic Framework Sieves for Efficient Propylene/Propane Separation

Abstract Membrane technology, regarded as an environmentally friendly and sustainable approach, offers great potential to address the large energy penalty associated with the energy‐intensive propylene/propane separation. Quest for molecular sieving membranes for this important separation is of tremendous interest. Here, a fluorinated metal–organic framework (MOF) material, known as KAUST‐7 (KAUST: King Abdullah University of Science and Technology) with well‐defined narrow 1D channels that can effectively discriminate propylene from propane based on a size‐sieving mechanism, is successfully incorporated into a polyimide matrix to fabricate molecular sieving mixed matrix membranes (MMMs). Markedly, the surface functionalization of KAUST‐7 nanoparticles with carbene moieties affords the requisite interfacial compatibility, with minimal nonselective defects at polymer–filler interfaces, for the fabrication of a molecular sieving MMM. The optimal membrane with a high MOF loading (up to 45 wt.%) displays a propylene permeability of ≈95 barrer and a mixed propylene/propane selectivity of ≈20, far exceeding the state‐of‐the‐art upper bound limits. Moreover, the resultant membrane exhibits robust structural stability under practical conditions, including high pressures (up to 8 bar) and temperatures (up to 100 °C). The observed outstanding performance attests to the importance of surface engineering for the preparation and plausible deployment of high‐performance MMMs for industrial applications.