Separation of a C3H6/C2H4 mixture using Pebax® 2533/PEG600 blend membranes

In industry, ethylene (C2H4)/propylene (C3H6) separations are usually performed by a cryogenic process, which is energy intensive. Membrane separation technology is an alternative separation process that saves energy and is efficient. In this study, blend membranes were prepared by doping polyethylene glycol (PEG600) into a poly(ether-block-amide) (Pebax® 2533) matrix and were used to separate the C2H4/C3H6 mixture. The PEG 600 and Pebax® 2533 polymers have good compatibility because they share hydrogen bonds. The addition of PEG600 is conducive to the hydrophilicity and the free volume of blend membranes, and it is also conducive to the solubility of C2H4 and C3H6 in the membranes, which improves the ability of the membranes to separate this gas pair. The Pebax® 2533/PEG600 blend membrane with 15% (mass) PEG600 showed the highest separation performance in our investigated membranes, with a C3H6/C2H4 selectivity of 8.9 and a C3H6 permeability of 196 barrer (1 barrer = 1.33 × 1014 m3(STP)·m·m−2·s−1·kPa−1) at 238 K and 0.2 MPa, which is higher than that of the Pebax® 2533/NaY-6% (mass) membrane (αC3H6/C2H4=6.5, PC3H6=211 barrer) reported in our previous work. It is confirmed that incorporating PEG600 into the Pebax® 2533 matrix to fabricate blend membranes is an efficient strategy for separating light olefins.