Enhanced propylene/propane separation in facilitated transport membranes containing multisilver complex

Facilitated transport membrane containing a zero complex Ag(4)tz(4) and 6FDA-TMPDA was fabricated via a solution-casting method and their separation performance toward C3H6/C3H8 was investigated. Ag(4)tz(4) complexes were well dispersed in the polymeric matrix owing to the weak hydrogen bond between Ag(4)tz(4) and 6FDA-TMPDA which can efficiently improve their interface compatibility. The reversible pi complexation between C3H6 and Ag+ facilitates the C3H6 transport in membranes, which is beneficial to achieve high C3H6/C3H8 permselectivity according to the density functional theory calculation. Remarkably, the best separation performance was achieved by the 10 wt% Ag(4)tz(4) membrane, for which the C3H6 permeability is 22 Barrer and the C3H6/C3H8 selectivity reaches up to 43, surpassing the Robeson upper bound. In addition, the membranes also exhibit great long-term stability (>120 h). The excellent separation performance together with the long-term stability render the membrane to be an interesting candidate for C3H6/C3H8 separation.