Researcher:
Sümer, Zeynep

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Master Student

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Zeynep

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Sümer

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Sümer, Zeynep

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2016 - 20174

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Researcher Of Publications: search.filters.isAuthorOfPublication.8d036b93-e641-4858-9a7f-1a04262e978d

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Now showing 1 - 4 of 4
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    Molecular simulations of MOF adsorbents and membranes for noble gas separations
    (Elsevier, 2017) N/A; Department of Chemical and Biological Engineering; Sümer, Zeynep; Keskin, Seda; Master Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 40548
    Molecular simulations were used to examine noble gas separation performances of MOF adsorbents and membranes. Grand canonical Monte Carlo simulations were combined with equilibrium molecular dynamics to compute adsorption and diffusion of Xe/Kr, Xe/Ar and Xe/Rn mixtures in 115 different MOF5. Several adsorbent evaluation metrics such as selectivity, working capacity, sorbent selection parameter, per cent regenerability were computed for each gas separation to identify the most promising MOFs. Relations between adsorption selectivity and structural properties of MOFs were also investigated to provide structure-property relationships that can serve as a guide for future experimental studies to design better adsorbents. Materials with pore sizes of 4.3-6.8 angstrom, surface areas of 150-1000 m(2)/g and porosities of 0.37-0.58 were found to be the best adsorbent candidates for Xe/Kr, Xe/Ar and Xe/Rn separations. Molecular simulations were then used to model MOFs as membranes for these gas separations. Membrane selectivities and gas permeabilities of 115 different MOFs were computed and a large number of MOFs was identified to outperform traditional polymer and zeolite membranes. MOFs with pore limiting diameters in the range of 3.9-5.7 angstrom were found to be the most promising membrane materials with high selectivities and high gas permeabilities. Our results showed that MOFs have the potential to replace traditional adsorbent and membrane materials in noble gas separation processes. (C) 2017 Elsevier Ltd. All rights reserved.
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    Ranking of MOF adsorbents for CO2 separations: a molecular simulation study
    (Amer Chemical Soc, 2016) N/A; Department of Chemical and Biological Engineering; Sümer, Zeynep; Keskin, Seda; Master Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 40548
    Identifying materials that can efficiently separate CO2 from natural gas (CO2/CH4), power-plant flue gas (CO2/N-2), and petroleum refinery gas streams (CO2/H-2) is crucial. We used molecular simulations to examine the adsorption-based separation performances of MOFs in the separations of CO2/CH4, CO2/N-2, and CO2/H-2 mixtures under different operating conditions. We first compared the results of our molecular simulations with the experimentally available data for the CO2 adsorption and separation performances of various MOFs. Motivated by the good agreement between simulations and experiments, we extended our simulations to 100 different MOF materials. Several adsorbent evaluation metrics including selectivity, working capacity, adsorption figure of merit, sorbent selection parameter, and percentage regenerability were computed for each MOF and for each gas separation. The rankings of the MOFs based on these metrics were examined in detail to understand which parameters play key roles in assessing the gas separation potential of MOF adsorbents. The results showed that regenerability is a very important metric for screening materials in the first step of the adsorbent search and MOFs can then be ranked according to selectivity. We also examined the relationships between easily computable structural properties of MOFs, such as pore size, surface area, and porosity, and adsorbent evaluation metrics to provide structure property relationships that can serve as a guide for experimental studies. Materials with pore sizes of 4-7 A, surface areas of 200-800 m(2)/g, and porosities of 0.18-0.50 were found to be the best adsorbent candidates for CO2/CH4, CO2/N-2, and CO2/H2 separations. Finally, the kinetic-based separation potentials of the MOFs that were identified as the top-performing materials for adsorption-based separations were analyzed. Both the membrane selectivities and the permeabilities of the MOFs were computed for three gas separation processes. Several MOFs were identified to outperform polymers and zeolites in membrane-based CO2 separations.
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    Adsorption- and membrane-based CH4/N2 separation performances of MOFs
    (Amer Chemical Soc, 2017) N/A; Department of Chemical and Biological Engineering; Sümer, Zeynep; Keskin, Seda; Master Student; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 40548
    Metal organic frameworks (MOFs) have been widely studied as adsorbents and membranes for gas separation applications. Considering the large number of available MOFs, it is not possible to fabricate and test the gas separation performance of every single MOF using purely experimental methods. In this study, we used molecular simulations to assess both adsorption-based and membrane-based CH4/N-2 separation performances of 102 different MOFs. This is the largest number of MOF adsorbents and membranes studied to date for separation of CH4/N-2 mixtures. Several adsorbent evaluation metrics such as adsorption selectivity, working capacity, and regenerability were predicted, and the top performing adsorbents were identified. Several MOFs were predicted to exhibit higher adsorption selectivities than the traditional adsorbents such as zeolites and activated carbons. Relation between adsorption-based separation performances of MOFs and their structural properties were also investigated. Results showed that MOFs having the largest cavity diameters in the range of 4.6-5.4 angstrom, pore limiting diameters in the range of 2.4-3.7 angstrom, surface areas less than 2000 m(2)/g, and porosities less than 0.5 are promising adsorbents for CH4/N-2 separations. We then combined adsorption and diffusion data obtained from molecular simulations and predicted both membrane selectivities and gas permeabilities of MOFs for separation of CH4/N-2 mixtures. A significant number of MOF membranes were identified to be CH4 selective in contrast to the traditional membrane materials which are generally N-2 selective. Several MOFs exceeded the upper bound established for the polymeric membranes, and many MOFs exhibited higher gas permeabilities than zeolites. The results of this study will be useful to guide the experiments to the most promising MOF adsorbents and membranes for efficient separation of CH4/N-2 mixtures.
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    Computational screening of MOF-based mixed matrix membranes for CO2/N2 separations
    (Hindawi, 2016) Department of Chemical and Biological Engineering; Keskin, Seda; Sümer, Zeynep; Master Student; Department of Chemical and Biological Engineering; College of Engineering; Graduate School of Sciences and Engineering; 40548; N/A
    Atomically detailed simulations were used to examine CO2/N-2 separation potential of metal organic framework- (MOF-) based mixed matrix membranes (mmms) in this study. Gas permeability and selectivity of 700 new mmms composed of 70 different mofs and 10 different polymers were calculated for CO2/N-2 separation. This is the largest number of MOF-based mmms for which computational screening is done to date. Selecting the appropriate mofs as filler particles in polymers resulted in mmms that have higher CO2/N-2 selectivities and higher CO2 permeabilities compared to pure polymer membranes. We showed that, for polymers that have low CO2 permeabilities but high CO2 selectivities, the identity of the MOF used as filler is not important. All mofs enhanced the CO2 permeabilities of this type of polymers without changing their selectivities. Several MOF-based mmms were identified to exceed the upper bound established for polymers. The methods we introduced in this study will create many opportunities to select the MOF/polymer combinations with useful properties for CO2 separation applications.