Adsorptive separation is very important in industry. Generally, the process uses porous solid materials such as zeolites, activated carbons, or silica gels as adsorbents. With an ever increasing need for a more efficient, energy-saving, and environmentally benign procedure for gas separation, adsorbents with tailored structures and tunable surface properties must be found. Metal–organic frameworks (MOFs), constructed by metal-containing nodes connected by organic bridges, are such a new type of porous materials. They are promising candidates as adsorbents for gas separations due to their large surface areas, adjustable pore sizes and controllable properties, as well as acceptable thermal stability. This critical review starts with a brief introduction to gas separation and purification based on selective adsorption, followed by a review of gas selective adsorption in rigid and flexible MOFs. Based on possible mechanisms, selective adsorptions observed in MOFs are classified, and primary relationships between adsorption properties and framework features are analyzed. As a specific example of tailor-made MOFs, mesh-adjustable molecular sieves are emphasized and the underlying working mechanism elucidated. In addition to the experimental aspect, theoretical investigations from adsorption equilibrium to diffusion dynamics via molecular simulations are also briefly reviewed. Furthermore, gas separations in MOFs, including the molecular sieving effect, kinetic separation, the quantum sieving effect for H2/D2 separation, and MOF-based membranes are also summarized (227 references).

Selective gas adsorption and separation in metal–organic frameworks

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

This critical review will be of interest to the experts in porous solids (including catalysis), but also solid state chemists and physicists. It presents the state-of-the-art on hybrid porous solids, their advantages, their new routes of synthesis, the structural concepts useful for their ‘design’, aiming at reaching very large pores. Their dynamic properties and the possibility of predicting their structure are described. The large tunability of the pore size leads to unprecedented properties and applications. They concern adsorption of species, storage and delivery and the physical properties of the dense phases. (323 references)

Hybrid porous solids: past, present, future

Metal Organic Frameworks in Biomedicine Patricia Horcajada,* Ruxandra Gref, Tarek Baati, Phoebe K. Allan, Guillaume Maurin, Patrick Couvreur, G erard F erey, Russell E. Morris, and Christian Serre* Institut Lavoisier, UMR CNRS 8180, Universit e de Versailles St-Quentin en Yvelines, 45 Avenue des Etats-Unis, 78035 Versailles Cedex, France Facult e de Pharmacie, UMR CNRS 8612, Universit e Paris-Sud, 92296 Châtenay-Malabry Cedex, France Institut Charles Gerhardt Montpellier, UMR CNRS 5253, Universit e Montpellier 2, 34095 Montpellier cedex 05, France EaStChem School of Chemistry, University of St. Andrews Purdie Building, St Andrews, KY16 9ST U.K.

Metal-organic frameworks in biomedicine.

/pdf/selective-adsorption-and-separation-of-xylene-isomers-and-40dgmr22fp.pdf

Selective Adsorption and Separation of Xylene Isomers and Ethylbenzene with the Microporous Vanadium(IV) Terephthalate MIL‐47

Separation of CO2/CH4 mixtures with the MIL-53(Al) metal–organic framework

Vapor-phase adsorption and separation of the C8 alkylaromatic components p-xylene, m-xylene, o-xylene, and ethylbenzene on the metal−organic framework MIL-47 have been studied. Low coverage Henry adsorption constants and adsorption enthalpies were determined using the pulse chromatographic technique at temperatures between 230 and 290 °C. The four C8 alkylaromatic components have comparable Henry constants and adsorption enthalpies. Adsorption isotherms of the pure components were determined using the gravimetric technique at 70, 110, and 150 °C. The adsorption capacity and steepness of the isotherms differs among the components and are strongly temperature dependent. Breakthrough experiments with several binary mixtures were performed at 70−150 °C and varying total hydrocarbon pressure from 0.0004 to 0.05 bar. Separation of the different isomers could be achieved. In general, it was found that the adsorption selectivity increases with increasing partial pressure or degree of pore filling. The separation ...

/pdf/pore-filling-dependent-selectivity-effects-in-the-vapor-306aaysq8f.pdf

Pore-filling-dependent selectivity effects in the vapor-phase separation of xylene isomers on the metal-organic framework MIL-47

Henry constants, low-coverage adsorption enthalpies, van't Hoff preexponential factors, and separation factors of C5−C8 alkanes are determined on beta, ZSM-5, ZSM-22, mordenite, and Y zeolites at 473−648 K using tracer and perturbation chromatographic techniques. Three different adsorption behaviors were encountered depending on the zeolite type:  (1) nonselective competitive adsorption of isoalkanes and n-alkanes inside the micropores (zeolite Y), (2) preferential adsorption of the n-alkanes over the isoalkanes inside the micropores (beta, ZSM-5 and mordenite), and (3) selective adsorption of the n-alkanes in the micropores and of the isoalkanes on the external crystal surfaces (ZSM-22). Linear and mono- and multibranched alkanes can be separated on columns of ZSM-22 and beta zeolites.

High-Temperature Low-Pressure Adsorption of Branched C5−C8 Alkanes on Zeolite Beta, ZSM-5, ZSM-22, Zeolite Y, and Mordenite

ZIF-8 is a flexible zeolitic imidazole-based metal–organic framework whose narrow pore apertures swing open by reorientation of imidazolate linkers and expand when probed with guest molecules. This...

/pdf/adsorption-and-diffusion-phenomena-in-crystal-size-52rlgb5ocz.pdf

Gino Baron

Papers

Selective Adsorption and Separation of Xylene Isomers and Ethylbenzene with the Microporous Vanadium(IV) Terephthalate MIL‐47

Separation of CO2/CH4 mixtures with the MIL-53(Al) metal–organic framework

Pore-filling-dependent selectivity effects in the vapor-phase separation of xylene isomers on the metal-organic framework MIL-47

High-Temperature Low-Pressure Adsorption of Branched C5−C8 Alkanes on Zeolite Beta, ZSM-5, ZSM-22, Zeolite Y, and Mordenite

Adsorption and Diffusion Phenomena in Crystal Size Engineered Zif‑8 MOF