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Grunenberg L, Keßler C, Teh TW, Schuldt R, Heck F, Kästner J, Groß J, Hansen N, Lotsch BV. Probing Self-Diffusion of Guest Molecules in a Covalent Organic Framework: Simulation and Experiment. ACS NANO 2024. [PMID: 38860455 DOI: 10.1021/acsnano.3c12167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
Covalent organic frameworks (COFs) are a class of porous materials whose sorption properties have so far been studied primarily by physisorption. Quantifying the self-diffusion of guest molecules inside their nanometer-sized pores allows for a better understanding of confinement effects or transport limitations and is thus essential for various applications ranging from molecular separation to catalysis. Using a combination of pulsed field gradient nuclear magnetic resonance measurements and molecular dynamics simulations, we have studied the self-diffusion of acetonitrile and chloroform in the 1D pore channels of two imine-linked COFs (PI-3-COF) with different levels of crystallinity and porosity. The higher crystallinity and porosity sample exhibited anisotropic diffusion for MeCN parallel to the pore direction, with a diffusion coefficient of Dpar = 6.1(3) × 10-10 m2 s-1 at 300 K, indicating 1D transport and a 7.4-fold reduction in self-diffusion compared to the bulk liquid. This finding aligns with molecular dynamics simulations predicting 5.4-fold reduction, assuming an offset-stacked COF layer arrangement. In the low-porosity sample, more frequent diffusion barriers result in isotropic, yet significantly reduced diffusivities (DB = 1.4(1) × 10-11 m2 s-1). Diffusion coefficients for chloroform at 300 K in the pores of the high- (Dpar = 1.1(2) × 10-10 m2 s-1) and low-porosity (DB = 4.5(1) × 10-12 m2 s-1) samples reproduce these trends. Our multimodal study thus highlights the significant influence of real structure effects such as stacking faults and grain boundaries on the long-range diffusivity of molecular guest species while suggesting efficient intracrystalline transport at short diffusion times.
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Affiliation(s)
- Lars Grunenberg
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, Stuttgart 70569, Germany
- Department of Chemistry, Ludwig-Maximilians-Universität (LMU), Butenandtstr. 5-13, Munich 81377, Germany
| | - Christopher Keßler
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, Pfaffenwaldring 9, Stuttgart 70569, Germany
| | - Tiong Wei Teh
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, Pfaffenwaldring 9, Stuttgart 70569, Germany
| | - Robin Schuldt
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, Stuttgart 70569, Germany
| | - Fabian Heck
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, Stuttgart 70569, Germany
- Department of Chemistry, Ludwig-Maximilians-Universität (LMU), Butenandtstr. 5-13, Munich 81377, Germany
| | - Johannes Kästner
- Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, Stuttgart 70569, Germany
| | - Joachim Groß
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, Pfaffenwaldring 9, Stuttgart 70569, Germany
| | - Niels Hansen
- Institute of Thermodynamics and Thermal Process Engineering, University of Stuttgart, Pfaffenwaldring 9, Stuttgart 70569, Germany
| | - Bettina V Lotsch
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, Stuttgart 70569, Germany
- Department of Chemistry, Ludwig-Maximilians-Universität (LMU), Butenandtstr. 5-13, Munich 81377, Germany
- E-conversion, Lichtenbergstrasse 4a, Garching 85748, Germany
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Gözcü O, Kayacı HU, Dou Y, Zhang W, Hedin N, Jasso-Salcedo AB, Kaiser A, Çınar Aygün S. Colloidal Stabilization of Submicron-Sized Zeolite NaA in Ethanol-Water Mixtures for Nanostructuring into Thin Films and Nanofibers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:192-203. [PMID: 36537794 PMCID: PMC9835981 DOI: 10.1021/acs.langmuir.2c02241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 11/28/2022] [Indexed: 06/17/2023]
Abstract
Despite the growing use of organic or mixed solvents in zeolite processing, most studies focus only on aqueous suspension systems. We investigated the colloidal characteristics of submicron-sized zeolite NaA in mixed ethanol-water solvents. The effects of the mixing ratio of solvents and various additives on the dispersion of the zeolite powders were studied. The zeolite NaA particles were destabilized in solvent mixtures at a high ethanol-to-water ratio, a reduction in the zeta potential was observed, and the destabilization was rationalized by the Derjaguin, Landau, Verwey, Overbeek (DLVO) theory. An improved stabilization of the zeolite NaA suspensions was achieved in ethanol-rich solvent mixtures using nonionic low molecular weight organic additives, but not with their ionic counterparts such as anionic, cationic surfactants or inorganic acids or bases. Polyethylene glycol (PEG)-400 was found to be a good dispersant for the submicron-sized zeolite NaA particles in the ethanol-water mixtures, which was attributed to its interaction with the zeolite surface, leading to an increased zeta potential. The PEG-stabilized zeolite suspensions led to low suspension viscosities as well as uniform and consistent spin-coated films.
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Affiliation(s)
- Oğuz Gözcü
- Department
of Metallurgical and Materials Engineering, Middle East Technical University (METU), 06800 Ankara, Türkiye
| | - H. Utkucan Kayacı
- Department
of Metallurgical and Materials Engineering, Middle East Technical University (METU), 06800 Ankara, Türkiye
| | - Yibo Dou
- Department
of Energy Conversion and Storage, Technical
University of Denmark, Anker Angelundsvej, 2800 Kongens Lyngby, Denmark
| | - Wenjing Zhang
- Department
of Environmental Engineering, Technical
University of Denmark, Bygninstorvet, 2800 Kongens Lyngby, Denmark
| | - Niklas Hedin
- Department
of Materials and Environmental Chemistry (MMK), Stockholm University, Svante Arrhenius väg 16 C, 10691 Stockholm, Sweden
| | - Alma B. Jasso-Salcedo
- Department
of Materials and Environmental Chemistry (MMK), Stockholm University, Svante Arrhenius väg 16 C, 10691 Stockholm, Sweden
| | - Andreas Kaiser
- Department
of Energy Conversion and Storage, Technical
University of Denmark, Anker Angelundsvej, 2800 Kongens Lyngby, Denmark
| | - Simge Çınar Aygün
- Department
of Metallurgical and Materials Engineering, Middle East Technical University (METU), 06800 Ankara, Türkiye
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Canevesi R, Grande CA. Biogas Upgrading by Pressure Swing Adsorption Using Zeolite 4A. Effect of Purge on Process Performance. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.123015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Li S, Chen J, Wang Y, Li K, Li K, Guo W, Zhang X, Liu J, Tang X, Yang J, Li J. Adsorption and separation of CH4/N2 by electrically neutral skeleton AlPO molecular sieves. Sep Purif Technol 2022. [DOI: 10.1016/j.seppur.2022.120497] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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