Researcher:
Haşlak, Zeynep Pınar

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Researcher

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Zeynep Pınar

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Haşlak

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Haşlak, Zeynep Pınar

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Exploring covalent organic frameworks for H2S+CO2 separation from natural gas using efficient computational approaches
(Elsevier Sci Ltd, 2022) Erucar, Ilknur; N/A; Department of Chemical and Biological Engineering; Department of Chemical and Biological Engineering; Aksu, Gökhan Önder; Haşlak, Zeynep Pınar; Keskin, Seda; PhD Student; Researcher; Faculty Member; Department of Chemical and Biological Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; 40548
Covalent organic frameworks (COFs) are emerged as strong adsorbent candidates for industrial gas separation applications due to their highly porous structures. In this work, we explored H2S+CO2 capture potentials of synthesized and computer-generated COFs from a natural gas mixture using an efficient, multi-level computational screening approach. We computed the adsorption data of a six-component natural gas mixture, CH4/C2H6/ CO2/C3H8/H2S/H2O, for 580 synthesized COFs by performing Grand Canonical Monte Carlo (GCMC) simulations under industrially relevant conditions. H2S+CO2 selectivities and working capacities of COFs were computed to be 0.4-12.4 (0.2-8.5) and 0.01-5.36 (0.04-2.5) mol/kg at pressure-swing adsorption (vacuum-swing adsorption) condition. NPN-3 was identified as the best performing COF due to the competitive adsorption of H2S+CO2 over C2H6 and C3H8 as revealed by density functional theory (DFT) calculations. Structural (pore sizes, porosities, and topologies) and chemical properties (linker units and heats of gas adsorption) of the best-performing synthesized COFs were used to efficiently screen the very large number of hypothetical COFs (hypoCOFs). Results showed that isosteric heats of adsorption can be used to discover high performing hypoCOFs for H2S+CO2 separation from natural gas. Finally, we compared COFs, hypoCOFs, zeolites, carbon nanotubes, metal organic frameworks (MOFs) and concluded that several synthesized and computer-generated COFs can outperform traditional adsorbents in terms of H2S+CO2 selectivities. Our results provide molecular-level insights about the potential of COFs for natural gas purification and direct the design and development of new COF materials with high H2S+CO2 selectivities.
Open Access
Assessing CH4/N2 separation potential of MOFs, COFs, IL/MOF, MOF/Polymer, and COF/Polymer composites
(Elsevier, 2022) Department of Chemical and Biological Engineering; Keskin, Seda; Uzun, Alper; Altıntaş, Çiğdem; Haşlak, Zeynep Pınar; Faculty Member; Researcher; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); College of Engineering; Graduate School of Sciences and Engineering; 40548; 59917; N/A; N/A
Separating CH4/N2 mixture is challenging, and performance of the existing materials is still open to improvement. In this study, we examined both the adsorption- and membrane-based CH4/N2 separation performances of 5034 different materials, including metal organic frameworks (MOFs), covalent organic frameworks (COFs), ionic liquid (IL)/MOF composites, MOF/polymer composites, and COF/polymer composites by performing high-throughput computational screening and molecular simulations. The top performing adsorbents and membranes were identified by computing several performance evaluation metrics. Investigation of the interactions between the gas molecules, the IL, and the top MOF was performed by density functional theory (DFT) calculations. Results pointed out that the interactions between the gas molecules and the linker fragments of the MOF are stronger than their interactions with the IL. Thus, as the IL molecules are loaded into the selected top MOF, they occupy the adsorption sites of the gases, decreasing CH4 and N2 uptakes and increasing the CH4/N2 selectivity. Our results revealed that MOFs offer great potential for adsorption-based CH4/N2 separation, and IL incorporation into MOFs remarkably increases their CH4/N2 selectivities. More than 25% of MOF and 70% of the COF membranes surpassed Robeson's upper bound because of high N2 permeabilities and outperformed conventional polymeric membranes. N2 permeabilities and selectivities of MOF/polymer and COF/polymer composites were found to be significantly higher than those of pure polymers. Our results emphasize the promises of the design and development of new MOF and COF adsorbents, membranes, and their composites with ILs and polymers for efficient CH4/N2 separation.
Open Access
Combined GCMC, MD, and DFT approach for unlocking the performances of COFs for methane purification
(American Chemical Society (ACS), 2021) Department of Chemical and Biological Engineering; Keskin, Seda; Haşlak, Zeynep Pınar; Altundal, Ömer Faruk; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; Graduate School of Sciences and Engineering; 40548; N/A; N/A
Covalent organic frameworks (COFs) are promising materials for gas storage and separation; however, the potential of COFs for separation of CH4 from industrially relevant gases such as H-2, N-2, and C2H6 is yet to be investigated. In this work, we followed a multiscale computational approach to unlock both the adsorption- and membrane-based CH4/H-2, CH4/N-2, and C2H6/CH4 separation potentials of 572 COFs by combining grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations and density functional theory (DFT) calculations. Adsorbent performance evaluation metrics of COFs, adsorption selectivity, working capacity, regenerability, and adsorbent performance score were calculated for separation of equimolar CH4/H-2, CH4/N-2, and C2H6/CH4 mixtures at vacuum swing adsorption (VSA) and pressure swing adsorption (PSA) conditions to identify the best-performing COFs for each mixture. Results showed that COFs could achieve selectivities of 2-85, 1-7, and 2-23 for PSA-based CH4/H-2, CH4/N-2, and C2H6/CH4 separations, respectively, outperforming conventional adsorbents such as zeolites and activated carbons for each mixture. Structure-performance relations revealed that COFs with pore sizes <10 angstrom are promising adsorbents for all mixtures. We identified the gas adsorption sites in the three top-performing COFs commonly identified for each mixture by DFT calculations and computed the binding strength of gases, which were found to be on the order of C2H6 > CH4 > N-2 > H-2, supporting the GCMC results. Nucleus-independent chemical shift (NICS) indexes of aromaticity for adsorption sites were calculated, and the results revealed that the degree of linker aromaticity could be a measure for the selection or design of highly alkane-selective COF adsorbents over N-2 and H-2. Finally, COF membranes were shown to achieve high H-2 permeabilities, 4.57 x 10(3)-1.25 x 10(6) Barrer, and decent membrane selectivities, as high as 4.3, outperforming polymeric and MOF-based membranes for separation of H-2 from CH4.
Open Access
Composites of porous materials with ionic liquids: synthesis, characterization, applications, and beyond
(Elsevier, 2022) Department of Chemical and Biological Engineering; Durak, Özce; Zeeshan, Muhammad; Habib, Nitasha; Gülbalkan, Hasan Can; Alsuhile, Ala Abdulalem Abdo Moqbel; Çağlayan, Hatice Pelin; Öztulum, Samira Fatma Kurtoğlu; Zhao, Yuxin; Haşlak, Zeynep Pınar; Uzun, Alper; Keskin, Seda; PhD Student; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); College of Engineering; Graduate School of Sciences and Engineering; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; N/A; 59917; 40548
Modification of the physicochemical properties of porous materials by using ionic liquids (ILs) has been widely studied for various applications. The combined advantages of ILs and porous materials provide great potential in gas adsorption and separation, catalysis, liquid-phase adsorption and separation, and ionic conductivity owing to the superior performances of the hybrid composites. In this review, we aimed to provide a perspective on the evolution of IL/porous material composites as a research field by discussing several different types of porous materials, including metal organic frameworks (MOFs), covalent organic frameworks (COFs), zeolites, and carbonaceous-materials. The main challenges and opportunities in synthesis methods, characterization techniques, applications, and future opportunities of IL/porous materials are discussed in detail to create a road map for the area. Future advances of the field addressed in this review will provide in-depth insights into the design and development of these novel hybrid materials and their replacement with conventional materials.
Open Access
An integrated computational-experimental hierarchical approach for the rational design of an IL/UiO-66 composite offering infinite CO2 selectivity
(Wiley, 2022) Department of Chemical and Biological Engineering; Department of Chemistry; Zeeshan, Muhammad; Gülbalkan, Hasan Can; Durak, Özce; Haşlak, Zeynep Pınar; Ünal, Uğur; Keskin, Seda; Uzun, Alper; PhD Student; Faculty Member; Faculty Member; Department of Chemical and Biological Engineering; Department of Chemistry; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); College of Engineering; College of Sciences; Graduate School of Sciences and Engineering; N/A; N/A; N/A; N/A; 42079; 40548; 59917
Owing to the possibility of generating theoretically unlimited numbers of ionic liquid (IL)-metal-organic framework (MOF) combinations, experimental studies on IL/MOF composites for gas separation applications are mostly conducted on a trial-and-error basis. To address this problem, an integrated computational-experimental hierarchical approach is presented for selecting the best IL-MOF combination for a target gas separation application. For this purpose, UiO-66 and pyrrolidinium-based ILs are chosen as the parent MOF and IL family, respectively, and three powerful computational tools, Conductor-like Screening Model for Realistic Solvents calculations, density functional theory calculations, and grand canonical Monte Carlo simulations, are integrated to identify the most promising IL-UiO-66 combination as 1-n-butyl-1-methylpyrrolidinium dicyanamide/UiO-66, [BMPyrr][DCA]/UiO-66. Then, this composite is synthesized, characterized in deep detail, and tested for CO2/N-2, CO2/CH4, and CH4/N-2 separations. Results demonstrate that [BMPyrr][DCA]/UiO-66 offers an extraordinary gas separation performance, with practically infinite CO2 and CH4 selectivities over N-2 at 15 degrees C and at low pressures. The integrated hierarchical approach proposed in this work paves the way for the rational design and development of novel IL/MOF composites offering exceptional performance for any desired gas separation application.
Open Access
Accelerating discovery of COFs for CO2 capture and H2 purification using structurally guided computational screening
(Elsevier, 2022) Eruçar, İlknur; Department of Chemical and Biological Engineering; Keskin, Seda; Aksu, Gökhan Önder; Haşlak, Zeynep Pınar; Faculty Member; Department of Chemical and Biological Engineering; College of Engineering; Graduate School of Sciences and Engineering; 40548; N/A; N/A
Screening of hypothetical covalent organic framework (hypoCOF) database enables to go beyond the current synthesized structures to design high-performance materials for CO2 separation. In this work, we followed a structurally guided computational screening approach to find the most promising candidates of hypoCOF adsorbents and membranes for CO2 capture and H2 purification. Grand canonical Monte Carlo (GCMC) simulations were used to evaluate CO2/H2 separation performance of 3184 hypoCOFs for pressure-swing adsorption (PSA) and vacuum-swing adsorption (VSA) processes. CO2/H2 adsorption selectivities and CO2 working capacities of hypoCOFs were calculated in the range of 6.13–742 (6.39–954) and 0.07–8.68 mol/kg (0.01–3.92 mol/kg), achieving higher values than those of experimentally synthesized COFs at PSA (VSA) conditions. Density functional theory (DFT) calculations revealed that the strength of hydrogen bonding between CO2 and the functional group of linkers is an important factor for determining the CO2 selectivity of hypoCOFs. The most predominant topologies and linker types were identified as bor and pts, linker91 (a triazine linker) and linker92 (a benzene linker) for the top-performing hypoCOF adsorbents, respectively. Molecular dynamics (MD) simulations of 794 hypoCOFs showed that they exceed the Robeson's upper bound by outperforming COF, zeolite, metal organic framework (MOF), and polymer membranes due to their high H2/CO2 selectivities, 2.66–6.14, and high H2 permeabilities, 9×105–4.5×106 Barrer. Results of this work will be useful to guide the synthesis of novel materials by providing molecular-level insights into the structural features of hypothetical COFs to achieve superior CO2 separation performance.
Open Access
Doubling CO2/N2 separation performance of CuBTC by incorporation of 1-n-ethyl-3-methylimidazolium diethyl phosphate
(Elsevier, 2021) Department of Chemical and Biological Engineering; Zeeshan, Muhammad; Gülbalkan, Hasan Can; Haşlak, Zeynep Pınar; Keskin, Seda; Uzun, Alper; PhD Student; Faculty Member; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; N/A; 40548; 59917
1-ethyl-3-methylimidazolium diethyl phosphate ([EMIM][DEP]) was incorporated into copper benzene-1,3,5-tricarboxylate, CuBTC. Consequences of molecular interactions on the CO2 separation performance of CuBTC were investigated. Scanning electron microscopy and X-ray diffraction results showed that the surface morphology and crystal structure of CuBTC remained intact upon the incorporation of the ionic liquid (IL); and the results of thermogravimetric analysis and infrared spectroscopy indicated the presence of interactions between the anion of the IL and the open metal sites of CuBTC. Gas adsorption measurements for the pristine CuBTC and IL-incorporated CuBTC were performed at 25 °C in a pressure range of 0.1–1 bar. Data showed that ideal CO2/CH4 and CO2/N2 selectivities of IL-incorporated CuBTC were 1.6- and 2.4-times higher compared to those of the pristine CuBTC at 0.01 bar, respectively. Moreover, for the CO2/CH4:50/50 and CO2/N2:15/85 mixtures, the corresponding selectivities were improved by more than 1.5- and 1.9-times compared to that of pristine CuBTC at 0.01 bar, respectively.
Open Access
Multi-scale computational screening to accelerate discovery of IL/COF composites for CO2/N-2 separation
(Elsevier, 2022) Department of Chemical and Biological Engineering; Uzun, Alper; Keskin, Seda; Gülbalkan, Hasan Can; Haşlak, Zeynep Pınar; Altıntaş, Çiğdem; Faculty Member; Researcher; Department of Chemical and Biological Engineering; Koç University Tüpraş Energy Center (KUTEM) / Koç Üniversitesi Tüpraş Enerji Merkezi (KÜTEM); Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); College of Engineering; Graduate School of Sciences and Engineering; 59917; 40548; N/A; N/A; N/A
Covalent organic frameworks (COFs) have emerged as novel adsorbents and membranes for gas separation. Incorporation of ionic liquids (ILs) into COFs is important to exceed the current performance limits of COFs. However, synthesis and testing of a nearly unlimited number of IL/COF combinations are simply impractical. Herein, we used a multi-scale computational screening approach combining COnductor-like Screening MOdel for Realistic Solvents (COSMO-RS) method, Grand Canonical Monte Carlo (GCMC), molecular dynamics (MD) simulations, and density functional theory (DFT) calculations to unlock both the adsorption-and membrane based CO2/N-2 separation performances of IL/COF composites. Several adsorbent and membrane performance assessment metrics including selectivity, working capacity, regenerability, adsorbent performance score, and permeability were computed. Our results revealed that IL incorporation into COFs significantly improves CO2/N-2 adsorption selectivities (from 12 to 26) and adsorbent performance scores (from 3.7 to 12 mol/kg). By performing DFT calculations, the nature of the interactions between CO2, N-2, COFs, and their IL-incorporated composites was evaluated. The high CO2 selectivity of IL/COF composites was attributed to the cooperative intermolecular effects induced by the COF and the IL. Finally, IL/COF membranes were studied, and results showed that they achieve significantly higher CO2 permeabilities (2.4 x 10(4)-9.4 x 10(5) Barrer) than polymeric and zeolite membranes with comparable selectivities (up to 15.7). This shows a great promise of IL/COF composites to replace the conventional membrane materials for flue gas separation. Our results will be useful in accelerating the experimental efforts to design new IL/COF composites that can achieve high-performance CO2 separation.