Crystalline metal-organic frameworks (MOFs) are formed by reticular synthesis, which creates strong bonds between inorganic and organic units. Careful selection of MOF constituents can yield crystals of ultrahigh porosity and high thermal and chemical stability. These characteristics allow the interior of MOFs to be chemically altered for use in gas separation, gas storage, and catalysis, among other applications. The precision commonly exercised in their chemical modification and the ability to expand their metrics without changing the underlying topology have not been achieved with other solids. MOFs whose chemical composition and shape of building units can be multiply varied within a particular structure already exist and may lead to materials that offer a synergistic combination of properties.

The Chemistry and Applications of Metal-Organic Frameworks

New materials hold the key to fundamental advances in energy conversion and storage, both of which are vital in order to meet the challenge of global warming and the finite nature of fossil fuels. Nanomaterials in particular offer unique properties or combinations of properties as electrodes and electrolytes in a range of energy devices. This review describes some recent developments in the discovery of nanoelectrolytes and nanoelectrodes for lithium batteries, fuel cells and supercapacitors. The advantages and disadvantages of the nanoscale in materials design for such devices are highlighted.

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Nanostructured materials for advanced energy conversion and storage devices

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

Styrene made from raw pyrolysis gasoline contains sulfur impurities such as 2-vinyl thiophene. We prepared three sorbents, namely, AgY, AgNO3/γ-Al2O3, and AgNO3/SiO2, to remove 2-vinyl thiophene from styrene. All three sorbents showed good desulfurization performance while AgY had the highest sulfur capacity. This was due to π-complexation, where the silver cations in AgY can bond 2-vinyl thiophene more strongly than styrene. The desulfurization capacity of AgNO3/γ-Al2O3 was better than that of AgNO3/SiO2 when taking its lower silver loading and surface area into consideration. Moreover, prewetting the sorbents was critical for desulfurization but can cause polymerization. Comparison between desulfurization of gasoline and styrene, using AgY, shows its superior sulfur adsorption capacity for desulfurization of styrene. A possible mechanism on the preferential adsorption for 2-vinyl thiophene over styrene by Ag+ is given via the comparison between thiophene and benzene.

Superior Silver Sorbents for Removing 2-Vinyl Thiophene from Styrene by π-Complexation

This review provides an introduction to the recent progress in the development of transition metal-exchanged zeolites and mixed oxide-based catalysts for the low-temperature selective catalytic reduction (SCR) of NOx with ammonia. The nature of the different active species over different catalysts and the corresponding relationship between their performance and catalytic properties as well as the mechanism and kinetics of SCR reaction on different catalysts are discussed. In addition, recent developments of H2-SCR are also reviewed.

Low-Temperature Selective Catalytic Reduction (SCR) of NOx with NH3 Over Zeolites and Metal Oxide-Based Catalysts and Recent Developments of H2-SCR

Recent development of theoretical models and experimental results on multicomponent surface diffusion and diffusion in molecular sieves have been briefly summarized The model development of multicomponent diffusion have been focused on four most attractive approaches which are: single-file approach, Maxwell-Stefan approach, irreversible ther-modynamics approach and kinetic approach and with a more detailed model derivations on the last one A step by step procedures for predicting multicomponent diffusion from single component information have been demonstrated in the examples Besides, a direct comparison between these four models for co- and counter-diffusion cases are also presented The single-file and irreversible thermodynamic models have the advantage of being easy to use and having no adjustable parameters The only information required for this prediction is single component diffusivities They can be used to predict multicomponent diffusion, especially, at the surface loadings The kinetic model is capable of predicting multicomponent diffusion between λij from 0 to 1 The λij is indicative of the level of molecular interactions which can be directly obtained from single component information Based on these comparisons, it is clear that the kinetic models is superior to the others

Chapter 9. Multicomponent diffusion in zeolites and multicomponent surface diffusion

The delaminated Fe203-pillared clay shows high activities for selective catalytic reduction (SCR) of NO by NH2 Temperature program desorption (TPD) studies show that large amounts of NO, are adsorbed on the pillared clay catalyst at the SCR reaction temperatures (ie near 400°C) This result indicates that a Langmuir-Hinshelwood type mechanism (for reaction between chemisorbed NO, and NH, on the surface to form N2) is operative for the pillared clay catalyst, which is in contrast to the SCR reaction on the commercial vanadia-based catalysts The SCR activities for the delaminated Fe203-pillared clay catalyst are higher than that of a commercial-type V2O5 + WO3/TiO2 catalyst under SO2 + H20 free conditions, but became lower in the presence of SO2 +l H20 However, when promoted by doping 1–3% Cr203, the pillared clay catalyst exhibits higher SCR activities than the commercial-type catalyst in the presence of S02 + H2O at all practical SCR reaction temperatures

Selective catalytic reduction of nitric oxide by ammonia on pillared clay catalysts: possible mechanism and promoters

Analyse thermodynamique de l'adsorption des melanges CH 4 -C 2 H 6 et C 2 H 6 -C 2 H 4 sur le charbon actif a 212,7°K et 301,4°K

Ralph T. Yang

Papers

Superior Silver Sorbents for Removing 2-Vinyl Thiophene from Styrene by π-Complexation

Low-Temperature Selective Catalytic Reduction (SCR) of NOx with NH3 Over Zeolites and Metal Oxide-Based Catalysts and Recent Developments of H2-SCR

Chapter 9. Multicomponent diffusion in zeolites and multicomponent surface diffusion

Selective catalytic reduction of nitric oxide by ammonia on pillared clay catalysts: possible mechanism and promoters

Thermodynamic analysis for rapid measurements of equilibrium adsorption from binary gas mixtures