Metal and Covalent Organic Frameworks for Membrane Applications

Abstract

Better and more efficient membranes are needed to face imminent and future scientific, technological and societal challenges. New materials endowed with enhanced properties are required for the preparation of such membranes. Metal and Covalent Organic Frameworks (MOFs and COFs) are a new class of crystalline porous materials with large surface area, tuneable pore size, structure, and functionality, making them a perfect candidate for membrane applications. In recent years an enormous number of articles have been published on the use of MOFs and COFs in preparation of membranes for various applications. This review gathers the work reported on the synthesis and preparation of membranes containing MOFs and COFs in the last 10 years. Here we give an overview on membranes and their use in separation technology, discussing the essential factors in their synthesis as well as their limitations. A full detailed summary of the preparation and characterization methods used for MOF and COF membranes is given. Finally, applications of these membranes in gas and liquid separation as well as fuel cells are discussed. This review is aimed at both experts in the field and newcomers, including students at both undergraduate and postgraduate levels, who would like to learn about preparation of membranes from crystalline porous materials.

Continuous MOF Membrane-Based Sensors via Functionalization of Interdigitated Electrodes

“…The selectively permeable material is typically a nanoporous material that limits the translocation of molecules based on size, charge or simply based on specific chemical and structural interaction [ 1 , 2 ]. Ideally, the membranes are as thin as possible to minimize translocation time and energy consumption while maintaining the required mechanical properties, so as to not fail while in use [ 3 ]. Defects in thin membranes, such as pinholes or grain boundaries, can severely limit membrane effectiveness and useful applications [ 1 , 2 , 4 , 5 ].…”

“…Membranes can easily be classified dependent on their compositions, including metallic, inorganic (e.g., metal organic frameworks (MOFs), zeolites, metal oxides, silica, or alumina), porous polymers, or hybrid membranes, which are composed of more than one type of material (such as zeolites dispersed in a polymer matrix) [ 1 , 2 , 3 ]. Hybrid membranes, also called mixed matrix membranes, allow utilization of the advantageous properties of the added materials to the overall membrane [ 1 , 3 , 6 ]. For example, zeolites and MOFs are not readily grown into a large defect free membrane.…”

“…MOFs are a class of hybrid organic-inorganic materials composed of metal ions and organic linker molecules [ 7 , 8 , 9 , 10 , 11 ]. The nanoporous nature of these materials often imparts extremely high surface areas [ 7 , 8 , 11 , 12 ] and makes them ideal for incorporation into membranes [ 3 , 6 , 13 , 14 , 15 ]. The high surface area and tunable pore size/shape combined with the ability to alter the composition and impart specific functionalities to tune and optimize their properties make MOFs a very versatile class of materials [ 8 , 10 , 16 , 17 ].…”

Hydrogen Selective SiCH Inorganic–Organic Hybrid/γ-Al2O3 Composite Membranes

“…The H 2 -permselectivities of the composite membrane measured in this study were briefly compared with those recently reported for other membranes composed of various materials systems, and their H 2 permeation data with α(H 2 /X) (X = N 2 (0.364 nm) [ 51 ] or O 2 (0.346 nm) [ 51 ]) measured under the dry condition at T ≤ 50 °C are listed in Table 3 [ 18 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 ]. Among them, novel ultrathin (9 nm thickness) graphene oxide membrane formed on an anodic oxidized alumina support (#09) exhibited a H 2 permeance of approximately 1 × 10 −7 mol m −2 s −1 Pa −1 with α(H 2 /N 2 ) of 900 at 20 °C [ 75 , 76 ].…”

“…Among them, novel ultrathin (9 nm thickness) graphene oxide membrane formed on an anodic oxidized alumina support (#09) exhibited a H 2 permeance of approximately 1 × 10 −7 mol m −2 s −1 Pa −1 with α(H 2 /N 2 ) of 900 at 20 °C [ 75 , 76 ]. The zeolite imidazolate framework (ZIF) nanosheet membrane (#08) also showed H 2 permeance of 2.04 × 10 −7 mol m −2 s −1 Pa −1 with high α(H 2 /N 2 ) of 66.6 at 30 °C [ 73 , 74 ]. Among other practical membranes, SiO 2 -based organic–inorganic hybrid membrane (#03) showed the highest H 2 permeance of 10 −6 mol m −2 s −1 Pa −1 order, while the α(H 2 /N 2 ) remained at 12 [ 68 ].…”