Mixed Matrix Membranes Based on MFI Zeolite Nanosheets with Tunable Thickness for CO2/CH4 and H2/CH4 Separation

Mixed matrix membranes (MMMs) combine the advantages of polymers and nanofillers. In this work, MFI zeolite nanosheets with different thicknesses (i.e., 40, 80, and 200 nm) were synthesized hydrothermally. MMMs were fabricated by incorporating MFI zeolite nanosheets into Tröger's base polymer (TB). Gas separation performance of the obtained MMMs was systematically investigated under different operation conditions (e.g., feed pressure and test temperature). Meanwhile, MMMs were also characterized using various techniques including SEM, FTIR, TGA, and XRD. Even though the presence of all three different MFI zeolite nanosheets significantly improved the gas permeability. It was found out the MMMs with MFI nanosheets in the lowest thickness (i.e., 40 nm) showed the highest improvement in both CO2 and H2 permeability (7.2 and 4.9 times, respectively), denoting developing zeolite nanosheet materials with small thickness could be a promising strategy to promote gas separation performances of MMMs.