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    Models used for permeability predictions of nanoporous materials revisited for H2/CH4 and H2/CO2 mixtures
    (Elsevier, 2022) Canturk, Behra; Salih, Ali; Gurdal, Yeliz
    High throughput screening of new generation nanoporous materials, e.g. metal organic frameworks (MOFs) and zeolitic imidazolate frameworks (ZIFs), for gas mixture separations have produced large amounts of data. Reported gas permeabilities have been mainly calculated using a simplified (approximate) approach. Perme-ability predictions of an alternative method (new method), proposed previously by our group, have shown to significantly improve the predictions of the approximate method for noble gas mixtures. Permeabilities calculated using Onsager coefficients, detailed method, are accepted as correct answers, however constructing Onsager coefficient matrix is computationally cumbersome and not feasible especially for the high throughput screening purposes. In this work, we question in what accuracy the approximate and new methods can predict gas permeabilities and permeation selectivities of gases with respect to the detailed method. We perform Grand Canonical Monte Carlo and Molecular Dynamics simulations for six ZIFs, namely ZIF-6, ZIF-10, ZIF-60, ZIF-69, ZIF-79, and ZIF-81. Permeabilities of H-2/CH4 and H-2/CO(2 )mixtures are selected as cases, since the dominating interactions of the gas species with the pores of the membranes are different. For the H-2/CH4 mixture, approximate and new methods predict H-2 permeability results of the detailed method sufficiently good. CH4 permeabilities of the approximate method reveal deviations from the correct answers, yet the new method improves the predictions of the approximate approach. In the case of H-2/CO2 mixture, H-2 permeabilities calculated by the approximate approach are in agreement with the detailed method, except for ZIF-60 and ZIF-79. For the CO2 permeability, approximate and new methods give significant deviations from the results calculated using the detailed method.
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    Öğe
    Noncovalent chemistry of xenon opens the door for anesthetic xenon recovery using Bio-MOFs
    (Royal Society of Chemistry, 2023) Canturk, Behra; Erarslan, Zekiye; Gurdal, Yeliz
    Designing an inexpensive and highly efficient recovery process for xenon (Xe) is gaining importance in the development of sustainable applications. Using metal organic frameworks (MOFs) for separating Xe from anesthetic gas mixtures has been a recent topic studied rarely and superficially in the literature. We theoretically investigated Xe recovery performances of 43 biological MOFs (Bio-MOFs) formed by biocompatible metal cations and biological endogenous linkers. Xe uptakes and Xe permeabilities in its binary mixtures with CO2, O2, and N2 were investigated by applying Grand Canonical Monte Carlo and Molecular Dynamics simulations. Materials with metalloporphyrin, hexacarboxylate, triazine, or pyrazole ligands, dimetallic paddlewheel units, relatively large pore sizes (PLD > 5 Å and LCD > 10 Å), large void fractions (?0.8), and large surface areas (>2900 m2 g?1) have been determined as top performing Bio-MOFs for Xe recovery. By applying Density Functional Theory simulations and generating electron density difference maps, we determined that Xe-host interactions in the top performing Bio-MOFs are maximized mainly due to noncovalent interactions of Xe, such as charge-induced dipole and aerogen-? interactions. Polarized Xe atoms in the vicinity of cations/anions as well as ? systems are fingerprints of enhanced guest-host interactions. Our results show examples of rarely studied aerogen interactions that play a critical role in selective adsorption of Xe in nanoporous materials. © 2023 The Royal Society of Chemistry.