Transformation of metal-organic frameworks for molecular sieving membranes

Abstract

The development of simple, versatile strategies for the synthesis of metal-organic framework (MOF)-derived membranes are of increasing scientific interest, but challenges exist in understanding suitable fabrication mechanisms. Here we report a route for the complete transformation of a series of MOF membranes and particles, based on multivalent cation substitution. Through our approach, the effective pore size can be reduced through the immobilization of metal salt residues in the cavities, and appropriate MOF crystal facets can be exposed, to achieve competitive molecular sieving capabilities. The method can also be used more generally for the synthesis of a variety of MOF membranes and particles. Importantly, we design and synthesize promising MOF membranes candidates that are hard to achieve through conventional methods. For example, our CuBTC/MIL-100 membrane exhibits 89, 171, 241 and 336 times higher H2 permeance than that of CO2, O2, N2 and CH4, respectively.

A new permeation model in porous filler–based mixed matrix membranes for CO2 separation

“…In this case, the gas transport of MMM containing inorganic porous filler particles is determined via the Knudsen diffusion . The molecular diffusion mechanism is demonstrated for the MMM containing nanomaterial filler particles such as CMSs, zeolitic imidazolate frameworks, and MOFs . Finally, the gas transport through glassy polymers is completed by the solution‐diffusion mechanism .…”

Microstructural Engineering and Architectural Design of Metal–Organic Framework Membranes

“…A series of MOF–MOF composite membranes have been fabricated and shown impressive separation performances . Jeong et al proposed a heteroepitaxial growth method to fabricate continuous and well‐intergrown ZIF‐8–ZIF‐67 composite membranes ( Figure ), which were realized by first heteroepitaxial growth of ZIF‐67 membranes from nanosized ZIF‐8 seed layers, followed by heteroepitaxial tertiary growth of ZIF‐8 overlayers on prepared ZIF‐67 membranes .…”

“…Prepared composite membranes exhibited unprecedentedly high separation factors of propylene over propane (≈200), possibly due to an enhanced grain‐boundary microstructure. Zhang et al reported a novel route for partial transformation of HKUST‐1 membranes into HKUST‐1–MIL‐100 composite membranes based on multivalent‐cation substitution under ambient conditions . Through this approach, pore apertures could be reduced through the immobilization of amorphous FeCl 3 residues in MIL‐100 cavities, and desired HKUST‐1 crystal facets could be exposed to provide competitive molecular sieving ability.…”

Mass transport through metal organic framework membranes

“…And it is worthy to note the entrance size and pore size of MOF are not always the same. The entrance size is usually smaller than pore size, such as HKUST-1 [118,119] and ZIF-8 [120]. Several ZIF membranes have been reported for gas separation due to their high chemical stability [95,96,[120][121][122].…”