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Removal of xenon (Xe) and krypton (Kr) from process off-gasescontaining400 ppm Xe, 40 ppm Kr, 78% N2, 21% O2, 0.9%Ar, 0.03% CO2, and so forth using adsorption was demonstratedfor the first time. Two well-known metal–organic frameworks(MOFs), HKUST-1 and Ni/DOBDC, which both have unsaturated metal centersbut different pore morphologies, were selected as novel adsorbents.Results of an activated carbon were also included for comparison.The Ni/DOBDC has higher Xe/Kr selectivities than those of the activatedcarbon and the HKUST-1. In addition, results show that the Ni/DOBDCand HKUST-1 can adsorb substantial amounts of Xe and Kr even whenthey are mixed in air. Moreover, the Ni/DOBDC can successfully separate400 ppm Xe from 40 ppm Kr and air containing O2, N2, and CO2with a Xe/Ke selectivity of 7.3 as indicatedby our breakthrough results. This shows a promising future for MOFsin radioactive nuclide separations from spent fuels. [ABSTRACT FROM AUTHOR]

The article presents a study on frustrated organic solids that display physical adsorption of gases. In this report, the authors discovered a type of material which they believe involves a frustration of the solvate lattice as it moves toward the thermodynamically stable desolvated state. Also, the authors present two crystal structures of a toluene solvate that are both nonporous and that represent two inactive phases with respect to gas sorption.

Molecular confinement plays a significant effect on trapped gas and solvent molecules. A fundamental understanding of gas adsorption within the porous confinement provides information necessary to design a material with improved selectivity. In this regard, metal–organic framework (MOF) adsorbents are ideal candidate materials to study confinement effects for weakly interacting gas molecules, such as noble gases. Among the noble gases, xenon (Xe) has practical applications in the medical, automotive and aerospace industries. In this Communication, we report an ultra‐microporous nickel‐isonicotinate MOF with exceptional Xe uptake and selectivity compared to all benchmark MOF and porous organic cage materials. The selectivity arises because of the near perfect fit of the atomic Xe inside the porous confinement. Notably, at low partial pressure, the Ni–MOF interacts very strongly with Xe compared to the closely related Krypton gas (Kr) and more polarizable CO2. Further 129Xe NMR suggests a broad isotropic chemical shift due to the reduced motion as a result of confinement. [ABSTRACT FROM AUTHOR]

Expansion and contraction of structurally flexible Metal–Organic Frameworks (MOFs) or Porous Coordination Polymers (PCPs) have been extensively studied from different structural and application perspectives including crystal engineering, structural characterization, and gas adsorption-separation applications. The flexibility of the MOFs or PCPs depends on a number of factors including the nature of secondary building units (SBUs), organic linkers, pore geometry and/or solvent molecules. The flexibility can lead to unique properties, especially in gas-adsorption-separation related applications that is not observed in rigid frameworks. In this review, we offer a brief summary regarding a fundamental understanding of framework expansion–contraction in flexible porous MOFs in terms of their design and structure tunability by covering representative examples in the literature. [ABSTRACT FROM AUTHOR]

Considering the rapidly rising CO2 level, there is a constant need for versatile materials which can selectively adsorb CO2 at low cost. The quest for efficient sorptive materials is still on since the practical applications of conventional porous materials possess certain limitations. In that context, we designed, synthesized, and characterized two novel supramolecular organic frameworks based on C-pentylpyrogallol[4]arene (PgC5) with spacer molecules, such as 4,4′-bipyridine (bpy). Highly optimized and symmetric intermolecular hydrogen-bonding interactions between the main building blocks and comparatively weak van der Waals interactions between solvent molecules and PgC5 leads to the formation of robust extended frameworks, which withstand solvent evacuation from the crystal lattice. The evacuated framework shows excellent affinity for carbon dioxide over nitrogen and adsorbs ca. 3 wt % of CO2 at ambient temperature and pressure. [ABSTRACT FROM AUTHOR]

In this review, we describe recent efforts to systematically study nano-structured metal organic frameworks (MOFs), also known as metal organic heat carriers, with particular emphasis on their application in heating and cooling processes. We used both molecular dynamics and grand canonical Monte Carlo simulation techniques to gain a molecular-level understanding of the adsorption mechanism of gases in these porous materials. We investigated the uptake of various gases such as refrigerants R12 and R143a. We also evaluated the effects of temperature and pressure on the uptake mechanism. Our computed results compared reasonably well with available measurements from experiments, thus validating our potential models and approaches. In addition, we investigated the structural, diffusive and adsorption properties of different hydrocarbons in Ni2(dhtp). Finally, to elucidate the mechanism of nanoparticle dispersion in condensed phases, we studied the interactions among nanoparticles in various liquids, such asn-hexane, water and methanol. [ABSTRACT FROM PUBLISHER]

A previously known class of porous coordination polymer (PCP) of formula [Cu(bpy-n)2(SiF6)] (bpy-1 = 4,4'-bipyridine; bpy-2 = 1,2-bis(4-pyridyl)ethene) has been studied to assess its selectivity toward CO2, CH4, N2, and H2O. Gas sorption measurements reveal that [Cu(bpy-1)2(SiF6)] exhibits the highest uptake for CO2 yet seen at 298 K and 1 atm by a PCP that does not contain open metal sites. Significantly, [Cu(bpy-1)2(SiF6)] does not exhibit particularly high uptake under the same conditions for CH4, N2, and, H2O, presumably because of its lack of open metal sites. Consequently, at 298 K and 1 atm [Cu(bpy-1)2(SiF6)] exhibits a relative uptake of CO2 over CH4 of ca. 10.5:1, the highest value experimentally observed in a compound without open metal sites. [Cu(bpy-2)2(SiF6)] exhibits larger pores and surface area than [Cu(bpy-1)2(SiF6)] but retains a high CO2/CH4 relative uptake of ca. 8:1. [ABSTRACT FROM AUTHOR]

The considerable number of important physical properties, including optical, electronic, and magnetic properties, of Prussian blue (PB) analogues have attracted fundamental and industrial interest. Nevertheless, the gas sorption properties of PB coordination compounds were only investigated very recently. In this work, we report the synthesis and gas sorption properties of PB nanocomposites with different size and shape obtained by using poly(vinylpyrrolidone) (PVP), chitosan, and dioctyl sodium sulfosuccinate (AOT) as stabilizers and structure directing agents. All three porous nanocrystals show high and selective CO2adsorption over CH4or N2. No distinct relationship was found between the size (or shape) of the nanosorbents and their gas uptake capacities. To our knowledge, this is the first report on the use of PB nanocomposites for CO2capture applications. [ABSTRACT FROM AUTHOR]