Preparation and Characterization of PIM-1/Modified Zeolite Mixed Matrix Membranes for CO2/N2 Separation

Mixed matrix membranes (MMMs) of polymer of intrinsic microporosity (PIM-1) is synthesized by incorporating modified zeolite (MZ) as the filler. Zeolite was treated with (3-Aminopropyl)-triethoxysilane (APTES). This treatment provided terminal amino groups to the zeolite by interaction between zeolite and ethoxy group of silane. MZ was systematically incorporated from 5 wt% to 15 wt% for evaluation of the improvement in gas separation behaviour. Physical characteristics and elemental analysis of MMMs were evaluated by X-ray photoelectron spectroscopy (XPS), X-ray diffraction analysis (XRD) and Fourier transform infrared (FTIR) spectroscopy. FTIR spectrum indicated physical interaction between PIM-1 and MZ. Scanning electron microscopy analysis (SEM) revealed the smooth surface morphology for PIM-1 membrane. Aggregates of MZ were observed from SEM analysis of PIM-1/MZ MMMs which indicated the formation of additional void volume. The Brunauer, Emmett, Teller (BET) analysis exhibited type I isotherm for PIM-1. The PIM-1 surface area was calculated to be 656 m2 g-1. Thermogravimetric analysis (TGA) revealed that membranes are thermally stable up to 460 ᴼC. Gas separation behaviour of MMMs was also evaluated with particular focus on CO2 /N2 separation. Permeability was observed to increase with increasing filler concentration. CO2 permeability was evaluated to increase from 2610 barrer for PIM-1 membrane to 5540 barrer for PIM-1/MZ MMM (15 wt%). Tremendous increase in permeability was observed for alcohol treated PIM-1/MZ MMMs. Aging analysis was performed by calculating the permeability for each membrane after 30, 60 and 90 days.