Metal–Organic Frameworks for Separations

Kenji Sumida, David L. Rogow, Jarad A. Mason, Thomas M. McDonald, Eric D. Bloch, Zoey R. Herm, Tae-Hyun Bae, Jeffrey R. Long

Carbon Dioxide Capture in Metal–Organic Frameworks

Synthesis of metal-organic frameworks (MOFs): routes to various MOF topologies, morphologies, and composites.

Carbon dioxide capture-related gas adsorption and separation in metal-organic frameworks

Metal-organic frameworks (MOFs) are an emerging class of porous materials with potential applications in gas storage, separations, catalysis, and chemical sensing. Despite numerous advantages, applications of many MOFs are ultimately limited by their stability under harsh conditions. Herein, the recent advances in the field of stable MOFs, covering the fundamental mechanisms of MOF stability, design, and synthesis of stable MOF architectures, and their latest applications are reviewed. First, key factors that affect MOF stability under certain chemical environments are introduced to guide the design of robust structures. This is followed by a short review of synthetic strategies of stable MOFs including modulated synthesis and postsynthetic modifications. Based on the fundamentals of MOF stability, stable MOFs are classified into two categories: high-valency metal-carboxylate frameworks and low-valency metal-azolate frameworks. Along this line, some representative stable MOFs are introduced, their structures are described, and their properties are briefly discussed. The expanded applications of stable MOFs in Lewis/Bronsted acid catalysis, redox catalysis, photocatalysis, electrocatalysis, gas storage, and sensing are highlighted. Overall, this review is expected to guide the design of stable MOFs by providing insights into existing structures, which could lead to the discovery and development of more advanced functional materials.

Stable Metal-Organic Frameworks: Design, Synthesis, and Applications.

New materials are prerequisite for major breakthrough applications influencing our daily life, and therefore are pivotal for the chemical industry. Metal–organic frameworks (MOFs) constitute an emerging class of materials useful in gas storage, gas purification and separation applications as well as heterogeneous catalysis. They not only offer higher surface areas and the potential for enhanced activity than currently used materials like base metal oxides, but also provide shape/size selectivity which is important both for separations and catalysis. In this critical review an overview of the potential applications of MOFs in the chemical industry is presented. Furthermore, the synthesis and characterization of the materials are briefly discussed from the industrial perspective (88 references).

Industrial applications of metal–organic frameworks

The progression of Al-based metal-organic frameworks – From academic research to industrial production and applications

Industrial Applications of Metal—Organic Frameworks

The limited resources of fossil fuels will soon require a change to renewable energies. The ideal energy carrier for mobile applications is hydrogen, but the problem of an adequate and safe storage system is still unsolved. One of the possibilities for hydrogen storage is physisorption in porous materials. The big advantage of molecular hydrogen storage is that short refuelling times can be realized due to the extremely fast kinetics. Additionally, no extra heat management is needed as the heat of adsorption is lower than for other storage processes, for example in metal hydrides. On the other hand, owing to this low heat of adsorption, a cryosystem is needed to reach high storage capacities. Microporous materials possessing a high specific surface area (SSA), for example carbon nanotubes, activated carbon, zeolites, and coordination polymers or metal–organic frameworks (MOFs), show a high hydrogen uptake at low temperatures, typically 77 K. Characteristic for this cryo-adsorption in porous materials is that the maximum hydrogen uptake at high pressures depends linearly on the SSA of the material. At low pressures distinct differences in the hydrogen uptake exist for the different materials. Therefore, the pressure to reach, for example, 80% of the maximum storage capacity, differs strongly between the materials. For all materials the hydrogen uptake decreases with increasing temperature. The strength of this decrease as well as the hydrogen uptake at low pressures are governed by the heat of adsorption. Typically, the isosteric heat of adsorption is calculated from the adsorption isotherms measured at 77 K and 87 K since these temperatures can easily be realized by liquid nitrogen and liquid argon, respectively. This small temperature range leads to a very high uncertainty in the heat of adsorption. Only in a few publications is the isosteric heat of adsorption determined with higher accuracy from several isotherms measured at various temperatures. Herein, we present hydrogen adsorption isotherms measured over a wide temperature (77–298 K) and pressure ACHTUNGTRENNUNG(0–20 bar) range. This allows the determination of the heat of adsorption for a wide range of surface coverage with very high accuracy. For the first time different microporous materials have been investigated systematically and their heats of adsorption are correlated to the structures of the materials. Two activated carbon samples, Norit R0.8 and Takeda 4A, with BET SSAs of 1384 mg 1 and 397 mg 1 respectively, and four different metal–organic frameworks, MOF-5, Cu-BTC, MIL-53 and MIL-101, with SSAs between 902 mg 1 and 3293 mg 1 have been investigated. The hydrogen uptake was measured with an automated Sieverts’ apparatus (PCTPro2000, HyEnergy, USA). Figure 1 shows the dependence of the hydrogen uptake on the pressure as an example for Cu-BTC (for other materials, see the Supporting Information). For all materials the isotherms at

Natalia Trukhan

Papers

Industrial applications of metal–organic frameworks

The progression of Al-based metal-organic frameworks – From academic research to industrial production and applications

Industrial Applications of Metal—Organic Frameworks

Heat of adsorption for hydrogen in microporous high-surface-area materials.

Industrial Outlook on Zeolites and Metal Organic Frameworks