In-situ growth of silver complex on ZIF-8 towards mixed matrix membranes for propylene/propane separation

Propylene/propane (C3H6/C3H8) separation is a typical energy-intensive industrial processes and the membrane-based separation technology is promising as its low-energy separation effectiveness. Hence, we developed a new ZIF-8 composite material as nanofillers that functionalized by a silver complex (Ag3pz3) via in-situ growth method. Density functional theory (DFT) calculation result shown that the Ag3pz3 exhibits much stronger interaction with C3H6 than that of C3H8, and this diversity can effectively facilitate C3H6 transport through membrane. Furthermore, this composite material reveals a preferable surface area and unique sieve pore structure that same as ZIF-8. Besides, the Ag complex have no destroy on ZIF-8 inner cage framework, which may confirm its potential for C3H6/C3H8 separation. Accordantly, such composite material was incorporated in polymer of intrinsic microporosity (PIM-1) to fabricate mixed-matrix membrane for C3H6/C3H8 separation. The optimum MMM possess a higher ideal selectivity (11.7) and propylene permeability (3767 Barrer), and exhibits a selectivity of 9.5 with propylene permeance of 3708 Barrer for a C3H6/C3H8 (50:50) mixture. Such high permeability with excellent selectivity surpasses the Trade-off line of polymer membrane and such MMMs may have significant potential for separation applications. Besides, this ZIF-8 composite material can provide inspirations for exploring and designing ZIFs materials in membrane-based gas separation.