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), Xray
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 aCO2=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.