Zeolitic Imidazolate Framework Membranes: Novel Synthesis Methods and Progress Toward Industrial Use

Abstract

In the last decade, zeolitic imidazolate frameworks (ZIFs) have been studied extensively for their potential as selective separation membranes. In this review, we highlight unique structural properties of ZIFs that allow them to achieve certain important separations, like that of propylene from propane, and summarize the state of the art in ZIF thin-film deposition on porous substrates and their modification by postsynthesis treatments. We also review the reported membrane performance for representative membrane synthesis approaches and attempt to rank the synthesis methods with respect to potential for scalability. To compare the dependence of membrane performance on membrane synthesis methods and operating conditions, we map out fluxes and separation factors of selected ZIF-8 membranes for propylene/propane separation. Finally, we provide future directions considering the importance of further improvements in scalability, cost effectiveness, and stable performance under industrially relevant conditions. Expected final online publication date for the Annual Review of Chemical and Biomolecular Engineering, Volume 13 is October 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Modeling of deposit formation in mesoporous substrates via atomic layer deposition: Insights from pore‐scale simulation

“…As the models are built via a finite‐volume code, they can be incorporated into ALD reactor‐scale models to form the reactor‐substrate multiscale models, which can be the primary tool of future computational research focused on scaling up LIPS‐based membrane fabrication 35 …”

Facile Fabrication of α-Alumina Hollow Fiber-Supported ZIF-8 Membrane Module and Impurity Effects on Propylene Separation Performance

“…Their huge pore volume, surface area, and broad range of accessible pore sizes [ 3 ] make them very desirable for applications such as adsorption [ 4 , 5 ], catalysis [ 6 , 7 , 8 ], and membranes [ 9 , 10 ]. In particular, due to its simple synthesis procedure and excellent chemical and thermal stability [ 11 ], ZIF-8 is a desirable membrane material [ 12 , 13 ]. In addition, ZIF-8 has shown an excellent pore size range (3–5 Å) [ 14 ], desirable for a number of industrially important gas pair separations [ 13 ], including C 3 H 6 /C 3 H 8 .…”

“…In particular, due to its simple synthesis procedure and excellent chemical and thermal stability [ 11 ], ZIF-8 is a desirable membrane material [ 12 , 13 ]. In addition, ZIF-8 has shown an excellent pore size range (3–5 Å) [ 14 ], desirable for a number of industrially important gas pair separations [ 13 ], including C 3 H 6 /C 3 H 8 .…”

Supramolecular modification of a metal–organic framework increases sorption switching: insights into reversible structural deformation of ZIF-8

“…18 While ZIF-8's pore aperture size was measured as 3.4 Å, the rotation of 2-mIm ligands allows molecules with kinetic diameters of up to 6.7 Å to diffuse through the framework while retaining its crystallinity, 19 which in turn enables selective separation of various gases such as propylene from propane. 20,21…”

“…18 While ZIF-8's pore aperture size was measured as 3.4 Å, the rotation of 2-mIm ligands allows molecules with kinetic diameters of up to 6.7 Å to diffuse through the framework while retaining its crystallinity, 19 which in turn enables selective separation of various gases such as propylene from propane. 20,21 ZIF-8 exhibits size-dependent gas adsorption dynamics where linker reorientation occurs at various pressures depending on crystal size. Reports on crystal size-dependent gateswitching behavior of ZIF-8 have demonstrated pressure and hysteresis width in N 2 and Ar gas adsorption isotherms to increase or decrease with a reduction in crystal size.…”