Ultrafast Semi‐Solid Processing of Highly Durable ZIF‐8 Membranes for Propylene/Propane Separation

Abstract

ZIF-8 membranes have emerged as the most promising candidate for propylene/propane (C 3 H 6 /C 3 H 8) separation through its precise molecular sieving characteristics. The poor reproducibility and durability, and high cost, thus far hinder the scalable synthesis and industrial application of ZIF-8 membranes. Herein, we report a semi-solid process featuring ultrafast and high-yield synthesis, and outstanding scalability for reproducible fabrication of ZIF-8 membranes. The membranes show excellent C 3 H 6 /C 3 H 8 separation performance in a wide temperature and pressure range, and remarkable stability over 6 months. The ZIF-8 membrane features dimethylacetamide entrapped ZIF-8 crystals retaining the same diffusion characteristics but offering enhanced adsorptive selectivity for C 3 H 6 /C 3 H 8. The ZIF-8 membrane was prepared on a commercial flat-sheet ceramic substrate. A prototypical plate-and-frame membrane module with an effective membrane area of about 300 cm 2 was used for efficient C 3 H 6 /C 3 H 8 separation.

ZIF‐8 Membrane Permselectivity Modification by Manganese(II) Acetylacetonate Vapor Treatment

“…[25] The performance is somewhat better when compared to the permeance and binary mixture separation factor (0.5 10 À8 mol m À2 Pa À1 s À1 and 190) of the recently reported dip coating-thermal conversion (DCTC) method. [26] Since the improved performance of the 165-Mn-ZIF-8 membranes is consistent with that of highly propyleneselective ZIF-8 membranes, it may be attributed in part to the reduction of grain boundary and other defects present in RTD membranes. However, the permeances of the 175-Mn-ZIF-8 membranes are distinct from those of ZIF-8 membranes and can be attributed to a continuous top layer.…”

“…This is a remarkably high mixture selectivity that approaches the propylene/propane selectivity of 305 reported for a ZIF‐8‐type membrane prepared by a fast current‐driven synthesis (FCDS) method [25] . The performance is somewhat better when compared to the permeance and binary mixture separation factor (0.5×10 −8 mol m −2 Pa −1 s −1 and 190) of the recently reported dip coating‐thermal conversion (DCTC) method [26] …”

Preferential adsorption sites for propane/propylene separation on ZIF-8 as revealed by solid-state NMR spectroscopy

“…18–27 Thus, it is essential to elucidate the detailed paraffin/olefin separation mechanisms for rational design of new functional MOFs with exceptional separation performance. Several main paraffin/olefin separation mechanisms including (i) equilibrium-based mechanism, 20,28,29 (ii) kinetic-based mechanism, 30–32 (iii) gate-opening effect, 18,33,34 and (iv) molecular sieving effect 35–38 have been generally studied to clarify the intrinsic structure–property relationship.…”

Weak Coordination Bond of Chloromethane: A Unique Way to Activate Metal Node Within an Unstable Metal–Organic Framework DUT‐34

“…Metal–organic frameworks (MOFs), which are assembled by the continuous link of coordination bonds between inorganic metal ions (or metal‐oxo clusters) and polydentate organic ligands, are a highly crystalline subset of these fascinating porous materials. With their permanent porosity, exceptionally high internal surface area, wide chemical variety, and tunable topology, MOFs have been examined for their potential in applications such as gas uptake, 1–8 molecular separation, 1,2,9–16 drug delivery, 1,17–20 sensing, 21–25 ion transport, 1,2,26–31 electronic conduction, 1,32–38 among others 39–44 …”