Metal–organic framework membranes: from synthesis to separation application

Abstract

Metal-organic framework (MOF) materials, which are constructed from metal ions or metal ion clusters and bridging organic linkers, exhibit regular crystalline lattices with relatively well-defined pore structures and interesting properties. As a new class of porous solid materials, MOFs are attractive for a variety of industrial applications including separation membranes - a rapidly developing research area. Many reports have discussed the synthesis and applications of MOFs and MOF thin films, but relatively few have addressed MOF membranes. This critical review provides an overview of the diverse MOF membranes that have been prepared, beginning with a brief introduction to the current techniques for the fabrication of MOF membranes. Gas and liquid separation applications with different MOF membranes are also included (175 references).

Zeolite membranes – a review and comparison with MOFs

“…133,134 Use of TEFS is advantageous over carbon-based silanes due to decomposition of the latter leading to re-formation of silanol groups upon calcination. 135 137 …”

High performance mixed matrix membranes (MMMs) composed of ZIF-94 filler and 6FDA-DAM polymer

“…Preparing such films is extremely challenging if not impossible because they should be self-supported with MOF phase densely packed, with no subnanometer defects between filler particles. MOF phase with such morphology was achieved only by in situ synthesis on top of porous supports [60] and was not the subject of this study. ZIF-94 (SIM-1) membrane has been crystallized in situ on a tubular asymmetric alumina support with pore size of 200 nm by Aguado et al [41].…”

Advanced Fabrication Method for the Preparation of MOF Thin Films: Liquid-Phase Epitaxy Approach Meets Spin Coating Method

“…It is to mention that serval research groups, including ours, had recognized the potential of MOF thin films in many key applications and thus the ongoing development of different MOFs thin film fabrication methods. 9,[14][15][16] The relative performance of MOF thin films, e.g. as a membrane for gas separation, is critically dependent on the film thickness and crystal orientation since the permeation of gases can vary along different crystallographic directions.…”

“…as a membrane for gas separation, is critically dependent on the film thickness and crystal orientation since the permeation of gases can vary along different crystallographic directions. 9,14 The adapted liquid phase epitaxy (LPE)…”

“…[15][16] These drawbacks will certainly hinder the scale up of this method for some important applications, specifically membrane-based technology where homogeneous MOF-coatings consisting of dense, defect free thick layers, measuring at least 0.5 µm, are required. 9,14 In an attempt to address this limitation, the first successful high-throughput approach was recently introduced to grow MOF thin layers on solid substrates using a spray method. [16][17] Here, "high-throughput" was used to express the time frame needed to prepare the MOF thin films, which was reduced by at least two orders of magnitude.…”