Polymer–ionic liquid composite membranes for propane/propylene separation by facilitated transport

In this work we propose the use of novel PVDF-HFP/BMImBF4–Ag+ facilitated transport membranes to carry out the separation of olefin/paraffin gas mixtures. These membranes exhibit good thermal, chemical and mechanical stability, good separation properties and easy manufacturing. The effect of membrane composition was evaluated concluding that the membrane with 80% polymer-20% IL w/w shows the best compromise between separation properties and mechanical resistance. The separation performance of membranes containing different concentrations of Ag+ in the range 0–80% w/w at temperatures between 293 and 323 K and different operational conditions has been evaluated. The facilitated transport membranes herein prepared provided very promising results when tested with 50/50%v/v C3H8/C3H6 mixtures obtaining C3H6 permeabilities up to 6630 barrer and C3H8/C3H6 selectivities over 700, placing these membranes well above the Robeson upper bound for polymeric and inorganic membranes. Moreover, these membranes showed excellent stability during long-term experiments carried out for 10 days.