MOF ligand side group regulation enables UiO-66/PDMS mixed-matrix membranes for ester/alcohol azeotropic separation

Currently, separation of ester/alcohol azeotropes such as methyl methacrylate (MMA)/methanol is a typical energy-intensive process using distillation technology. In principle, pervaporation membrane technology can separate azeotropes with higher energy efficiency, while the membrane performance could not meet the application requirement. We reported a new type of MOF ligand side group regulated UiO-66/PDMS mixed-matrix membranes (MMMs) to selectively separate MMA from the its methanol azeotrope. The incorporation of UiO-66 fillers improved the MMA/methanol performance of PDMS membrane. The results of molecular simulation and characterizations revealed that compared with the pristine UiO-66 and UiO-66-CH 3 , amino groups of UiO-66-NH 2 showed stronger interaction energy and thus higher affinity towards MMA molecule. Therefore, although the pore size of UiO-66-NH 2 is larger than the molecular kinetic diameters of MMA and methanol, the tunable chemical environment and molecular interaction promoted the selective transport of MMA. The optimal UiO-66-NH 2 /PDMS MMM displayed an outstanding separation performance with a total flux of 2.07 kg m −2  h −1 and a separation factor of 5.7 for 18 wt% MMA/methanol azeotrope at 40 °C. The membrane exhibited an excellent long-term performance during continuous separation process of ∼3400 h, and showed potential in scale-up fabrication and separation of other ester/alcohol azeotropes. The proposed MOF ligand side group regulation offers a promising strategy to develop high-performance membranes for azeotropic separation.