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3. Spreading Fundamentals

Author

Bunde, Armin, Chmelik, Christian, Kärger, Jörg, Vogl, Gero, Bunde, Armin, editor, Caro, Jürgen, editor, Chmelik, Christian, editor, Kärger, Jörg, editor, and Vogl, Gero, editor

Published
2023
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6. Transport in Nanoporous Materials Including MOFs: The Applicability of Fick’s Laws

Author

Titze, Tobias, Lauerer, Alexander, Heinke, Lars, Chmelik, Christian, Zimmermann, Nils ER, Keil, Frerich J, Ruthven, Douglas M, and Kärger, Jörg

Subjects
Biological Transport, Magnetic Resonance Spectroscopy, Microscopy, Models, Chemical, Nanostructures, Porosity, diffusion, Fick's laws, metal-organic frameworks, nanoporous materials, zeolites, Fick’s laws, Chemical Sciences, Organic Chemistry
Abstract

Diffusion in nanoporous host-guest systems is often considered to be too complicated to comply with such "simple" relationships as Fick's first and second law of diffusion. However, it is shown herein that the microscopic techniques of diffusion measurement, notably the pulsed field gradient (PFG) technique of NMR spectroscopy and microimaging by interference microscopy (IFM) and IR microscopy (IRM), provide direct experimental evidence of the applicability of Fick's laws to such systems. This remains true in many situations, even when the detailed mechanism is complex. The limitations of the diffusion model are also discussed with reference to the extensive literature on this subject.

Published
2015

8. Spreading Fundamentals

Author

Bunde, Armin, Chmelik, Christian, Kärger, Jörg, Vogl, Gero, Bunde, Armin, editor, Caro, Jürgen, editor, Kärger, Jörg, editor, and Vogl, Gero, editor

Published
2018
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18. Diffusion in Nanoporous Materials: Challenges, Surprises and Tasks of the Day

Author

Chmelik, Christian, Hwang, Seungtaik, Kärger, Jörg, Chmelik, Christian, Hwang, Seungtaik, and Kärger, Jörg

Abstract

Diffusion is an omnipresent, most fundamental phenomenon in nature and thus critical for the performance of numerous technologies. This is in particular true for nanoporous materials with manifold applications for matter upgrading by separation, purification and conversion. The path lengths of molecular transportation within the industrial plants range from the elementary steps of diffusion within the micropores of the individual particles up to the matter flow over macroscopic distances. Each of them might be decisive in determining overall performance so that detailed knowledge of all modes of mass transfer is crucial for a knowledge-based optimization of the devices with reference to their transport properties. The rate of mass transfer is particularly complicated to be assessed within the individual (adsorbent) particles/crystallites with pore sizes of the order of molecular dimensions. We are going to present two powerful techniques exactly for this application, operating under both equilibrium (Pulsed Field Gradient (PFG) NMR) and non-equilibrium (Microimaging by interference microscopy and IR microscopy) conditions. The potentials of these techniques are demonstrated in a few showcases, notably including the options of transport enhancement in pore hierarchies. The contribution concludes with a survey on present activities within an IUPAC initiative aiming at the elaboration of “guidelines for measurements and reporting of diffusion properties of chemical compounds in nanoporous materials”.

Published
2022

30. Molecules in nanopores as a model system for mimicking spreading in nature and society

Author

Hwang, Seungtaik, Chmelik, Christian, and Kärger, Jörg

Subjects
diffusion, nanoporous materials, ddc:530
Abstract

With reference to these advantages, the poster goes the other way round and identifies a couple of similarities where, on looking at molecular diffusion in nanoporous materials, one is able to recognize features of spreading, which may occur in quite different fields of research. The examples presented include (i) considering molecular uptake and release with nanoporous particles as a model for, respectively, occupation of a habitat by a new species and, vice versa, for the loss of a species in this habitat [2], (ii) the effect of additional highways on overall mass transfer [3,4], (iii) transport impediment (and enhancement!) by diffusant interference [5], (iv) invader-induced changes in the host system [2] and (v) host-induced changes of the invaders [6].

Published
2019

31. Exploring guest dynamics in nanoporous host materials

Author

Chmelik, Christian and Kärger, Jörg

Subjects
diffusion, nanoporous material, ddc:530
Abstract

Diffusion is an omnipresent phenomenon in nature. In the world of molecules, it describes their irregular thermal motion. The interplay of diffusion and interaction of molecules with pore walls of nanoporous materials constitutes the benefit of using such materials in applications of separation and catalysis. The need for understanding the rate-limiting mechanisms, further optimization and development of new processes makes this topic subject of continued fundamental research [1].

Published
2019

32. Metal–Organic Framework Co-MOF-74-Based Host–Guest Composites for Resistive Gas Sensing

Author

Strauss, Ina, Mundstock, Alexander, Treger, Marvin, Lange, Karsten, Hwang, Seungtaik, Chmelik, Christian, Rusch, Pascal, Bigall, Nadja C., Pichler, Thomas, Shiozawa, Hidetsugu, and Caro, Jürgen

Subjects
gas sensing, Dewey Decimal Classification::500 | Naturwissenschaften::540 | Chemie, tetrathiafulvalene, ddc:540, Guest@MOF, infiltration of MOFs, conducting MOFs
Abstract

Increasing demands in thefield of sensing, especially for gas detectionapplications, require new approaches to chemical sensors. Metal−organic frameworks (MOFs) can play a decisive role owing to their outstanding performances regardinggas selectivity and sensitivity. The tetrathiafulvalene (TTF)-infiltrated MOF, Co-MOF-74, has been prepared following the host−guest concept and evaluated inresistive gas sensing. The Co-MOF-74-TTF crystal morphology has beencharacterized via X-ray diffraction and scanning electron microscopy, while thesuccessful incorporation of TTF into the MOF has been validated via X-rayphotoemission spectroscopy, thermogravimetric analysis, UV/vis, infrared (IR), andRaman investigations. We demonstrate a reduced yet ample uptake of CO2in thepores of the new material by IR imaging and adsorption isotherms. Thenanocomposite Co-MOF-74-TTF exhibits an increased electrical conductivity incomparison to Co-MOF-74 which can be influenced by gas adsorption from asurrounding atmosphere. This effect could be used for gas sensing.

Published
2019
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33. Revealing Transient Concentration of CO2 in a Mixed Matrix Membrane by IR Microimaging and Molecular Modeling

Author

Hwang, Seungtaik, Semino, Rocio, Seoane de la Cuesta, Beatriz, Zahan, Marufa, Chmelik, Christian, Valiullin, Rustem, Bertmer, Marko, Haase, Jürgen, Kapteijn, Freek, Gascon, Jorge, Maurin, Guillaume, Kärger, Jörg, Sub Inorganic Chemistry and Catalysis, and Inorganic Chemistry and Catalysis

Abstract

Through IR microimaging the spatially and temporally resolved development of the CO2 concentration in a ZIF‐8@6FDA‐DAM mixed matrix membrane was visualized during transient adsorption. By recording the evolution of the CO2 concentration, it is observed that the CO2 molecules propagate from the ZIF‐8 filler, which acts as a transport "highway", towards the surrounding polymer. A high‐CO2‐concentration layer is formed at the MOF/polymer interface, which becomes more pronounced at higher CO2 gas pressures. A microscopic explanation of the origins of this phenomenon is suggested by means of molecular modeling. By applying a computational methodology combining quantum and force‐field based calculations, the formation of microvoids at the MOF/polymer interface is predicted. Grand Canonical Monte Carlo simulations further demonstrate that CO2 tends to preferentially reside in these microvoids, which is expected to facilitate CO2 accumulation at the interface.

Published
2018

39. Regular intergrowth in the AFI-type crystals: influence on the intracrystalline adsorbate distribution as observed by interference and FTIR-microscopy

Author

Lehmann, Enrico, Chmelik, Christian, Scheidt, Holger, Vasenkov, Sergey, Staudte, Brigitte, Karger, Jorg, Kremer, Friedrich, Zadrozna, Gabriela, and Kornatowski, Jan

Subjects
Zeolites -- Chemical properties, Crystals -- Chemical properties, Fourier transform infrared spectroscopy -- Usage, Methanol -- Chemical properties, Methanol -- Research, Chemistry
Abstract

The report stated that the equilibrium intracrystalline concentration profile of methanol was recorded in CrAPO-5 crystals by interference and FTIR microscopy. The study stated that two-dimensional concentration profiles of an unprecedented quality were reported, which showed a nonhomogeneous distribution of adsorbate in zeotite cyrstal under equilibrium with the adsorbate vapor.

Published
2002

40. Revealing Transient Concentration of CO2 in a Mixed Matrix Membrane by IR Microimaging and Molecular Modeling

Author

Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Hwang, Seungtaik, Semino, Rocio, Seoane de la Cuesta, Beatriz, Zahan, Marufa, Chmelik, Christian, Valiullin, Rustem, Bertmer, Marko, Haase, Jürgen, Kapteijn, Freek, Gascon, Jorge, Maurin, Guillaume, Kärger, Jörg, Sub Inorganic Chemistry and Catalysis, Inorganic Chemistry and Catalysis, Hwang, Seungtaik, Semino, Rocio, Seoane de la Cuesta, Beatriz, Zahan, Marufa, Chmelik, Christian, Valiullin, Rustem, Bertmer, Marko, Haase, Jürgen, Kapteijn, Freek, Gascon, Jorge, Maurin, Guillaume, and Kärger, Jörg

Published
2018

41. Transport in nanoporous materials including MOFs : the applicability of Fick’s laws

Author

Titze, Tobias, Lauerer, Alexander, Heinke, Lars, Chmelik, Christian, Zimmermann, Nils E. R., Keil, Frerich, Ruthven, Douglas M., Kärger, Jörg, Titze, Tobias, Lauerer, Alexander, Heinke, Lars, Chmelik, Christian, Zimmermann, Nils E. R., Keil, Frerich, Ruthven, Douglas M., and Kärger, Jörg

Abstract

Die Diffusion in nanoporösen Wirt-Gast-Systemen wird oft als viel zu kompliziert angesehen, als dass sie mit so “einfachen” Beziehungen wie dem ersten und zweiten Fickschen Gesetz vereinbar sein könnte. Wir zeigen nun, dass die mikroskopischen Diffusionsmesstechniken, vor allem die NMR-Spektroskopie mit gepulsten Feldgradienten (PFG) und die Mikrobildgebung mittels Interferenzmikroskopie (IFM) und IR-Mikroskopie (IRM), den direkten experimentellen Nachweis für die Anwendbarkeit der Fickschen Gesetze auf solche Systeme liefern. Dies gilt oft auch dann noch, wenn die zugrundeliegenden Transportmechanismen komplex sind. Die Grenzen des Diffusionsmodells werden unter Bezugnahme auf die umfangreiche Literatur diskutiert., Diffusion in nanoporous host-guest systems is often considered to be too complicated to comply with such “simple” relations as Fick’s first and second laws of diffusion. However, we show here that the microscopic techniques of diffusion measurement, notably the pulsed field gradient (PFG) technique of NMR and micro-imaging by interference microscopy (IFM) and IR microscopy (IRM), provide direct experimental evidence of the applicability of Fick’s laws to such systems. This remains true in many situations, even when the detailed mechanism is complex. The limitations of the diffusion model are also discussed with reference to the extensive literature of this subject.

Published
2018

43. Einblicke in die Verteilung von CO2 -Molekülen und deren zeitliche Entwicklung durch Mikro-Bildgebung mittels IR-Spektroskopie und molekulardynamische Modellierung

Author

Hwang, Seungtaik, primary, Semino, Rocio, additional, Seoane, Beatriz, additional, Zahan, Marufa, additional, Chmelik, Christian, additional, Valiullin, Rustem, additional, Bertmer, Marko, additional, Haase, Jürgen, additional, Kapteijn, Freek, additional, Gascon, Jorge, additional, Maurin, Guillaume, additional, and Kärger, Jörg, additional

Published
2018
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44. Revealing the Transient Concentration of CO2 in a Mixed‐Matrix Membrane by IR Microimaging and Molecular Modeling

Author

Hwang, Seungtaik, primary, Semino, Rocio, additional, Seoane, Beatriz, additional, Zahan, Marufa, additional, Chmelik, Christian, additional, Valiullin, Rustem, additional, Bertmer, Marko, additional, Haase, Jürgen, additional, Kapteijn, Freek, additional, Gascon, Jorge, additional, Maurin, Guillaume, additional, and Kärger, Jörg, additional

Published
2018
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47. List of contributors

Author

Bandosz, Teresa J., Chmelik, Christian, Dan Zhao, Derewinski, Miroslaw A., Ding, Frank, Do, D.D., Du, Shangfeng, Gelles, Teresa, Glover, T. Grant, Johnson, Brandy J., Kärger, Jörg, Krishnamurthy, Anirudh, Lawson, Shane, Li-Oakey, Katie Dongmei, Liu, Jian, Loi, Quang K., Ma, Ruoshi, Melde, Brian J., Mu, Bin, Nicholson, D., Peh, Shing Bo, Prasetyo, Luisa, Prodinger, Sebastian, Ramasamy, Karthikeyan K., Rezaei, Fateme, Rownaghi, Ali A., Shi, Hui, Sui, Sheng, Tan, Shiliang (Johnathan), Thakkar, Harshul, Wang, Huamin, Winarta, Joseph, Xu, Hui, Yung, Andra, and Zhang, Huixin

Published
2020
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48. Internal concentration gradients of guest molecules in nanoporous host materials: Measurement and microscopic analysis

Author

Kortunov, Pavel, Heinke, Lars, Vasenkov, Sergey, Chmelik, Christian, Shah, Dhananjai B., Karger, Jorg, Rakoczy, Rainer A., Traa, Yvonne, and Weitkamp, Jens

Subjects
Methanol -- Structure, Crystals -- Structure, Crystals -- Research, Chemicals, plastics and rubber industries
Abstract

The evolution of internal concentration profile of methanol in two-dimensional (2-D) pore structure of ferrierite crystal is measured with the help of interference microscopy technique. The results have indicated the importance of measuring the evolution of concentration profiles, as this is crucial in determining the direction of internal transport, the presence of internal structural defects and surface/internal transport barriers.

Published
2006

50. Molecular Dynamics Phenomena of Water in the Metalorganic Framework MIL-100(Al), as Revealed by Pulsed Field Gradient NMR and Atomistic Simulation

Author

Splith, Tobias, primary, Pantatosaki, Evangelia, additional, Kolokathis, Panagiotis D., additional, Fröhlich, Dominik, additional, Zhang, Kang, additional, Füldner, Gerrit, additional, Chmelik, Christian, additional, Jiang, Jianwen, additional, Henninger, Stefan K., additional, Stallmach, Frank, additional, and Papadopoulos, George K., additional

Published
2017
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