Separation of Binary Mixtures of Propylene and Propane by Facilitated Transport through Silver Incorporated Poly(Ether-Block-Amide) Membranes

The separation of propylene and propane is a challenging task in petroleum refineries due to the similar molecular sizes and physical properties of two gases. Composite Poly(ether-block-amide) (Pebax-1657) membranes incorporated with silver tetra fluoroborate (AgBF4 ) in concentrations of 0-50% of the polymer weight were prepared by solution casting and solvent evaporation technique. The membranes were characterized by Scanning Electron Microscopy (SEM), Fourier Transform InfraRed (FTIR) and wide-angle X-ray Diffraction (XRD) to study surface and cross-sectional morphologies, effect of incorporation on intermolecular interactions and degree of crystallinity, respectively. Experimental data was measured with an indigenously built high-pressure gas separation manifold having an effective membrane area of 42 cm2 . Permeability and selectivity of membranes were determined for three different binary mixtures of propylene-propane at pressures varying in the range 2-6 bar. Selectivity of C3 H6 /C3 H8 enhanced from 2.92 to 17.22 and 2.11 to 20.38 for 50/50 and 66/34 C3 H6 +C3 H8 feed mixtures, respectively, with increasing loading of AgBF4 . Pebax membranes incorporated with AgBF4 exhibit strong potential for the separation of C3 H6 /C3 H8 mixtures in petroleum refineries.