Separation of CO2 from CH4 using polysulfone/polyimide silica nanocomposite membranes

Mixed matrix membranes (MMMs) were developed by incorporating inorganic silica nanoparticles into blends of polysulfone/polyimide (PSF/PI) asymmetric membranes for gas separation using phase inversion technique. The membranes were characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA). SEM results show different morphologies of surfaces and cross-sections of the membrane where agglomeration is observed at 20.1 wt.% silica loading. TGA analysis indicates good thermal stability of the hybrid membranes. Permeation results show that CO2 permeance increased with the introduction of 5.2 wt.% silica contents (73.7 ± 0.2 GPU) in PSF/PI-20% blend and it increased with the increase in silica contents. With 15.2 wt.% silica contents, the highest permselectivity of αCO2/CH4αCO2/CH4 = 61.0 ± 0.3–60.2 ± 0.4 is observed for treated membrane at 2–10 bar. The selectivity using mixed gas test at various CO2/CH4 compositions shows consistent results with the ideal gas selectivity.

► Development of mixed matrix membranes at various silica compositions, in polymeric blends.
► Membrane characterizations were in good agreement with developed hybrid membranes.
► Improved gas performance resulted for both pure and mixed gases with silica S3 contents in PSF/PI-20% blends.