Uniformly Distributed Mixed Matrix Membranes via a Solution Processable Strategy for Propylene/Propane Separation

Aggregation of filler particles during the formation of mixed matrix membranes is difficult to avoid when filler loadings exceed a 10–15 wt %. Such agglomeration usually leads to poor membrane performance. In this work, using a ZIF‐67 metal–organic framework (MOF) as filler along with surface modification of Ag4tz4 to improve processability and selective olefin adsorption, we demonstrate that highly loaded with a very low agglomeration degree membranes can be synthesized displaying unmatched separation selectivity (39) for C3H6/C3H8 mixtures and high permeability rates (99 Barrer), far surpassing previous reports in the literature. Through molecular dynamics simulation, the enhanced compatibility between ZIF‐67 and polymer matrix with adding Ag4tz4 was proven and the tendency in gas permeability and C3H6 selectivity in the mixed matrix membranes (MMMs) were well explained. More importantly, the membrane showed a wide range of pressure and temperature resistance, together with remarkable long‐term stability (>900 h). The modification method might help solve interface issues in MMMs and can be extended to the fabrication of other fillers to achieve high performance MMMs for gas separation. A nanocomposite named as ZIF‐67@Ag4tz4 was introduced into 6FDA‐TMPDA to give advanced mixed matrix membranes (MMMs) for propylene/propane separation. The dual‐facilitated mechanism (facilitate transport and molecular sieving) of the nanocomposite results in a significantly improved propylene/propane selectivity, which was clarified with the help of computational studies.