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Krishna R, van Baten JM. Using Molecular Simulations to Unravel the Benefits of Characterizing Mixture Permeation in Microporous Membranes in Terms of the Spreading Pressure. ACS OMEGA 2020; 5:32769-32780. [PMID: 33376915 PMCID: PMC7759009 DOI: 10.1021/acsomega.0c05269] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 11/30/2020] [Indexed: 06/12/2023]
Abstract
The separation performance of microporous crystalline materials in membrane constructs is dictated by a combination of mixture adsorption and intracrystalline diffusion characteristics; the permeation selectivity S perm is a product of the adsorption selectivity S ads and the diffusion selectivity, S diff. The primary objective of this article is to gain fundamental insights into S ads and S diff by use of molecular simulations. We performed configurational-bias Monte Carlo (CBMC) simulations of mixture adsorption equilibrium and molecular dynamics (MD) simulations of guest self-diffusivities of a number of binary mixtures of light gaseous molecules (CO2, CH4, N2, H2, and C2H6) in a variety of microporous hosts of different pore dimensions and topologies. Irrespective of the bulk gas compositions and bulk gas fugacities, the adsorption selectivity, S ads, is found to be uniquely determined by the adsorption potential, Φ, a convenient and practical proxy for the spreading pressure π that is calculable using the ideal adsorbed solution theory for mixture adsorption equilibrium. The adsorption potential Φ is also a proxy for the pore occupancy and is the thermodynamically appropriate yardstick to determine the loading and composition dependences of intracrystalline diffusivities and diffusion selectivities, S diff. When compared at the same Φ, the component permeabilities, Π i for CO2, CH4, and N2, determinable from CBMC/MD data, are found to be independent of the partners in the various mixtures investigated and have practically the same values as the values for the corresponding unary permeabilities. In all investigated systems, the H2 permeability in a mixture is significantly lower than the corresponding unary value. These reported results have important practical consequences in process development and are also useful for screening of materials for use as membrane devices.
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Krishna R, van Baten JM. Water/Alcohol Mixture Adsorption in Hydrophobic Materials: Enhanced Water Ingress Caused by Hydrogen Bonding. ACS OMEGA 2020; 5:28393-28402. [PMID: 33163823 PMCID: PMC7643331 DOI: 10.1021/acsomega.0c04491] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/13/2020] [Accepted: 10/09/2020] [Indexed: 06/11/2023]
Abstract
Microporous crystalline porous materials such as zeolites, metal-organic frameworks, and zeolitic imidazolate frameworks (ZIFs) have potential use for separating water/alcohol mixtures in fixed bed adsorbers and membrane permeation devices. For recovery of alcohols present in dilute aqueous solutions, the adsorbent materials need to be hydrophobic in order to prevent the ingress of water. The primary objective of this article is to investigate the accuracy of ideal adsorbed solution theory (IAST) for prediction of water/alcohol mixture adsorption in hydrophobic adsorbents. For this purpose, configurational bias Monte Carlo (CBMC) simulations are used to determine the component loadings for adsorption equilibrium of water/methanol and water/ethanol mixtures in all-silica zeolites (CHA, DDR, and FAU) and ZIF-8. Due to the occurrence of strong hydrogen bonding between water and alcohol molecules and attendant clustering, IAST fails to provide quantitative estimates of the component loadings and the adsorption selectivity. For a range of operating conditions, the water loading in the adsorbed phase may exceed that of pure water by one to two orders of magnitude. Furthermore, the occurrence of water-alcohol clusters moderates size entropy effects that prevail under pore saturation conditions. For quantitative modeling of the CBMC, simulated data requires the application of real adsorbed solution theory by incorporation of activity coefficients, suitably parameterized by the Margules model for the excess Gibbs free energy of adsorption.
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Maxwell-Stefan modelling of mixture desorption kinetics in microporous crystalline materials. Sep Purif Technol 2019. [DOI: 10.1016/j.seppur.2019.115790] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Krishna R. Thermodynamically Consistent Methodology for Estimation of Diffusivities of Mixtures of Guest Molecules in Microporous Materials. ACS OMEGA 2019; 4:13520-13529. [PMID: 31460481 PMCID: PMC6705243 DOI: 10.1021/acsomega.9b01873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2019] [Accepted: 07/26/2019] [Indexed: 06/10/2023]
Abstract
The Maxwell-Stefan (M-S) formulation, that is grounded in the theory of irreversible thermodynamics, is widely used for describing mixture diffusion in microporous crystalline materials such as zeolites and metal-organic frameworks (MOFs). Binary mixture diffusion is characterized by a set of three M-S diffusivities: Đ 1, Đ 2, and Đ 12. The M-S diffusivities Đ 1 and Đ 2 characterize interactions of guest molecules with pore walls. The exchange coefficient Đ 12 quantifies correlation effects that result in slowing-down of the more mobile species due to correlated molecular jumps with tardier partners. The primary objective of this article is to develop a methodology for estimating Đ 1, Đ 2, and Đ 12 using input data for the constituent unary systems. The dependence of the unary diffusivities Đ 1 and Đ 2 on the pore occupancy, θ, is quantified using the quasi-chemical theory that accounts for repulsive, or attractive, forces experienced by a guest molecule with the nearest neighbors. For binary mixtures, the same occupancy dependence of Đ 1 and Đ 2 is assumed to hold; in this case, the occupancy, θ, is calculated using the ideal adsorbed solution theory. The exchange coefficient Đ 12 is estimated from the data on unary self-diffusivities. The developed estimation methodology is validated using a large data set of M-S diffusivities determined from molecular dynamics simulations for a wide variety of binary mixtures (H2/CO2, Ne/CO2, CH4/CO2, CO2/N2, H2/CH4, H2/Ar, CH4/Ar, Ne/Ar, CH4/C2H6, CH4/C3H8, and C2H6/C3H8) in zeolites (MFI, BEA, ISV, FAU, NaY, NaX, LTA, CHA, and DDR) and MOFs (IRMOF-1, CuBTC, and MgMOF-74).
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Krishna R. Thermodynamic Insights into the Characteristics of Unary and Mixture Permeances in Microporous Membranes. ACS OMEGA 2019; 4:9512-9521. [PMID: 31172049 PMCID: PMC6545543 DOI: 10.1021/acsomega.9b00907] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 05/20/2019] [Indexed: 06/09/2023]
Abstract
The primary objective of this article is to gain fundamental insights into the dependences of component permeances Π i in microporous membranes on the operating conditions (upstream partial pressures, temperature, and feed composition). It is argued that the permeances Π i for unary systems and mixtures need to be compared on the basis of the adsorption potential πA/RT, a convenient and practical proxy for the spreading pressure π that is calculable using the ideal adsorbed solution theory for mixture adsorption equilibrium. The use of πA/RT as a yardstick serves to elucidate and rationalize a wide variety of published experimental Π i data on unary and mixture permeances in microporous membranes. For cage-type host structures such as SAPO-34, DDR, and ZIF-8, the Π i values are uniquely dictated by the magnitude of πA/RT, irrespective of the partner species in the mixture. For MFI membranes, the tardier species slows down the more mobile partners due to correlated molecular motion within the channels; the degree of correlation is also a function of πA/RT.
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Krishna R. Highlighting the Influence of Thermodynamic Coupling on Kinetic Separations with Microporous Crystalline Materials. ACS OMEGA 2019; 4:3409-3419. [PMID: 30847432 PMCID: PMC6398361 DOI: 10.1021/acsomega.8b03480] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 01/31/2019] [Indexed: 06/02/2023]
Abstract
The main focus of this article is on mixture separations that are driven by differences in intracrystalline diffusivities of guest molecules in microporous crystalline adsorbent materials. Such "kinetic" separations serve to over-ride, and reverse, the selectivities dictated by mixture adsorption equilibrium. The Maxwell-Stefan formulation for the description of intracrystalline fluxes shows that the flux of each species is coupled with that of the partner species. For n-component mixtures, the coupling is quantified by a n × n dimensional matrix of thermodynamic correction factors with elements Γ ij ; these elements can be determined from the model used to describe the mixture adsorption equilibrium. If the thermodynamic coupling effects are essentially ignored, i.e., the Γ ij is assumed to be equal to δ ij , the Kronecker delta, the Maxwell-Stefan formulation degenerates to yield uncoupled flux relations. The significance of thermodynamic coupling is highlighted by detailed analysis of separations of five different mixtures: N2/CH4, CO2/C2H6, O2/N2, C3H6/C3H8, and hexane isomers. In all cases, the productivity of the purified raffinate, containing the tardier species, is found to be significantly larger than that anticipated if the simplification Γ ij = δ ij is assumed. The reason for the strong influence of Γ ij on transient breakthroughs is traceable to the phenomenon of uphill intracrystalline diffusion of more mobile species. The major conclusion to emerge from this study is that modeling of kinetic separations needs to properly account for the thermodynamic coupling effects.
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Krishna R. Occupancy Dependency of Maxwell-Stefan Diffusivities in Ordered Crystalline Microporous Materials. ACS OMEGA 2018; 3:15743-15753. [PMID: 30533580 PMCID: PMC6275975 DOI: 10.1021/acsomega.8b02465] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 11/06/2018] [Indexed: 06/02/2023]
Abstract
Molecular dynamics simulation data for a variety of binary guest mixtures (H2/CO2, Ne/CO2, CH4/CO2, CO2/N2, H2/CH4, H2/Ar, CH4/Ar, Ar/Kr, Ne/Ar, CH4/C2H6, CH4/C3H8, C2H6C3H8, CH4/nC4H10, and CH4/nC5H11) in zeolites (MFI, BEA, ISV, FAU (all-silica), NaY, NaX, LTA, CHA, DDR) and metal-organic frameworks (MOFs) (IRMOF-1, CuBTC, MgMOF-74) show that the Maxwell-Stefan (M-S) diffusivities, Đ 1, Đ 2, Đ 12, are strongly dependent on the molar loadings. The main aim of this article is to develop a fundamental basis for describing the loading dependence of M-S diffusivities. Using the ideal adsorbed solution theory, a thermodynamically rigorous definition of the occupancy, θ, is derived; this serves as a convenient proxy for the spreading pressure, π, and provides the correct metric to describe the loading dependence of diffusivities. Configurational-bias Monte Carlo simulations of the unary adsorption isotherms are used for the calculation of the spreading pressure, π, and occupancy, θ. The M-S diffusivity, Đ i , of either constituent in binary mixtures has the same value as that for unary diffusion, provided the comparison is made at the same θ. Furthermore, compared at the same value of θ, the M-S diffusivity Đ i of any component in a mixture does not depend on it partner species. The Đ i versus θ dependence is amenable to simple interpretation using lattice-models. The degree of correlations, defined by the ratio Đ 1/Đ 12, that characterizes mixture diffusion shows a linear increase with occupancy θ, implying that correlations become increasingly important as pore saturation conditions are approached.
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The Maxwell–Stefan description of mixture permeation across nanoporous graphene membranes. Chem Eng Res Des 2018. [DOI: 10.1016/j.cherd.2018.03.033] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Li Z, Ma X, Xiong S, Ye Y, Yao Z, Lin Q, Zhang Z, Xiang S. Facile synthesis of oxidized activated carbons for high-selectivity and low-enthalpy CO2 capture from flue gas. NEW J CHEM 2018. [DOI: 10.1039/c8nj00109j] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The oxidized activated carbon obtained using a facile synthetic approach shows high-capacity and low-enthalpy CO2 capture with a selectivity of 48.5 toward flue gas, which is double that of the pristine activated carbon.
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Affiliation(s)
- Ziyin Li
- Fujian Provincial Key Laboratory of Polymer Materials
- College of Chemistry and Materials Science
- Fujian Normal University
- Fuzhou 350007
- P. R. China
| | - Xiuling Ma
- Fujian Provincial Key Laboratory of Polymer Materials
- College of Chemistry and Materials Science
- Fujian Normal University
- Fuzhou 350007
- P. R. China
| | - Shunshun Xiong
- Institute of Nuclear Physics and Chemistry
- China Academy of Engineering Physics
- Mianyang
- P. R. China
| | - Yingxiang Ye
- Fujian Provincial Key Laboratory of Polymer Materials
- College of Chemistry and Materials Science
- Fujian Normal University
- Fuzhou 350007
- P. R. China
| | - Zizhu Yao
- Fujian Provincial Key Laboratory of Polymer Materials
- College of Chemistry and Materials Science
- Fujian Normal University
- Fuzhou 350007
- P. R. China
| | - Quanjie Lin
- Fujian Provincial Key Laboratory of Polymer Materials
- College of Chemistry and Materials Science
- Fujian Normal University
- Fuzhou 350007
- P. R. China
| | - Zhangjing Zhang
- Fujian Provincial Key Laboratory of Polymer Materials
- College of Chemistry and Materials Science
- Fujian Normal University
- Fuzhou 350007
- P. R. China
| | - Shengchang Xiang
- Fujian Provincial Key Laboratory of Polymer Materials
- College of Chemistry and Materials Science
- Fujian Normal University
- Fuzhou 350007
- P. R. China
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Krishna R. A Maxwell-Stefan-Glueckauf description of transient mixture uptake in microporous adsorbents. Sep Purif Technol 2018. [DOI: 10.1016/j.seppur.2017.09.057] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Krishna R. Using the Maxwell-Stefan formulation for highlighting the influence of interspecies (1−2) friction on binary mixture permeation across microporous and polymeric membranes. J Memb Sci 2017. [DOI: 10.1016/j.memsci.2017.06.062] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Krishna R, Baur R, van Baten JM. Highlighting diffusional coupling effects in zeolite catalyzed reactions by combining the Maxwell–Stefan and Langmuir–Hinshelwood formulations. REACT CHEM ENG 2017. [DOI: 10.1039/c7re00001d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The combined phenomena of intra-crystalline adsorption, diffusion and reversible chemical reactions inside microporous crystalline zeolite catalyst particles are described by combining the Langmuir–Hinshelwood kinetics with the Maxwell–Stefan (M–S) diffusion formulation.
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Affiliation(s)
- Rajamani Krishna
- Van 't Hoff Institute for Molecular Sciences
- University of Amsterdam
- 1098 XH Amsterdam
- The Netherlands
| | - Richard Baur
- Van 't Hoff Institute for Molecular Sciences
- University of Amsterdam
- 1098 XH Amsterdam
- The Netherlands
| | - Jasper M. van Baten
- Van 't Hoff Institute for Molecular Sciences
- University of Amsterdam
- 1098 XH Amsterdam
- The Netherlands
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Hye Kwon Y, Kiang C, Benjamin E, Crawford P, Nair S, Bhave R. Krypton‐xenon separation properties of SAPO‐34 zeolite materials and membranes. AIChE J 2016. [DOI: 10.1002/aic.15434] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Yeon Hye Kwon
- School of Chemical & Biomolecular EngineeringGeorgia Institute of TechnologyAtlanta GA30332‐0100
| | - Christine Kiang
- School of Chemical & Biomolecular EngineeringGeorgia Institute of TechnologyAtlanta GA30332‐0100
| | - Emily Benjamin
- School of Chemical & Biomolecular EngineeringGeorgia Institute of TechnologyAtlanta GA30332‐0100
| | - Phillip Crawford
- School of Chemical & Biomolecular EngineeringGeorgia Institute of TechnologyAtlanta GA30332‐0100
| | - Sankar Nair
- School of Chemical & Biomolecular EngineeringGeorgia Institute of TechnologyAtlanta GA30332‐0100
| | - Ramesh Bhave
- Oak Ridge National LaboratoryMaterials Science & Technology DivisionOak Ridge TN37831
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Ye P, Grahn M, Korelskiy D, Hedlund J. Efficient separation of N
2
and he at low temperature using MFI membranes. AIChE J 2016. [DOI: 10.1002/aic.15258] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Pengcheng Ye
- Chemical Technology, Luleå University of TechnologySE‐971 87Luleå Sweden
| | - Mattias Grahn
- Chemical Technology, Luleå University of TechnologySE‐971 87Luleå Sweden
| | - Danil Korelskiy
- Chemical Technology, Luleå University of TechnologySE‐971 87Luleå Sweden
| | - Jonas Hedlund
- Chemical Technology, Luleå University of TechnologySE‐971 87Luleå Sweden
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Krishna R. Tracing the origins of transient overshoots for binary mixture diffusion in microporous crystalline materials. Phys Chem Chem Phys 2016; 18:15482-95. [DOI: 10.1039/c6cp00132g] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Due to thermodynamic coupling overshoots in the loading of the more mobile species are observed during transient uptake.
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Affiliation(s)
- Rajamani Krishna
- Van ‘t Hoff Institute for Molecular Sciences
- University of Amsterdam
- 1098 XH Amsterdam
- The Netherlands
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Wang J, Krishna R, Yang J, Deng S. Hydroquinone and Quinone-Grafted Porous Carbons for Highly Selective CO2 Capture from Flue Gases and Natural Gas Upgrading. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2015; 49:9364-9373. [PMID: 26114815 DOI: 10.1021/acs.est.5b01652] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Hydroquinone and quinone functional groups were grafted onto a hierarchical porous carbon framework via the Friedel-Crafts reaction to develop more efficient adsorbents for the selective capture and removal of carbon dioxide from flue gases and natural gas. The oxygen-doped porous carbons were characterized with scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, and Raman spectroscopy. CO2, CH4, and N2 adsorption isotherms were measured and correlated with the Langmuir model. An ideal adsorbed solution theory (IAST) selectivity for the CO2/N2 separation of 26.5 (298 K, 1 atm) was obtained on the hydroquinone-grafted carbon, which is 58.7% higher than that of the pristine porous carbon, and a CO2/CH4 selectivity value of 4.6 (298 K, 1 atm) was obtained on the quinone-grafted carbon (OAC-2), which represents a 28.4% improvement over the pristine porous carbon. The highest CO2 adsorption capacity on the oxygen-doped carbon adsorbents is 3.46 mmol g(-1) at 298 K and 1 atm. In addition, transient breakthrough simulations for CO2/CH4/N2 mixture separation were conducted to demonstrate the good separation performance of the oxygen-doped carbons in fixed bed adsorbers. Combining excellent adsorption separation properties and low heats of adsorption, the oxygen-doped carbons developed in this work appear to be very promising for flue gas treatment and natural gas upgrading.
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Affiliation(s)
| | - Rajamani Krishna
- ‡Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Jiangfeng Yang
- §Research Institute of Special Chemicals, Taiyuan University of Technology, Taiyuan 030024, Shanxi, PR China
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Malakhov A, Volkov A. Application of coupled solution-diffusion model in organic solvent nanofiltration: Positive and negative rejection of solutes. SEP SCI TECHNOL 2015. [DOI: 10.1080/01496395.2015.1031403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Abstract
Diffusional coupling effects may cause uphill transport of a species against its concentration gradient. Transient overshoots and serpentine equilibration trajectories in composition space are fingerprints of uphill diffusion. Serpentine diffusion trajectories may enter meta-stable zones, leading to spontaneous emulsification and the Ouzo effect.
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Affiliation(s)
- Rajamani Krishna
- Van't Hoff Institute for Molecular Sciences
- University of Amsterdam
- 1098 XH Amsterdam
- The Netherlands
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Krishna R. Methodologies for evaluation of metal–organic frameworks in separation applications. RSC Adv 2015. [DOI: 10.1039/c5ra07830j] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The separation performance of fixed-bed adsorbers is governed by a number of factors that include (a) adsorption selectivity, (b) uptake capacity, and (c) intra-crystalline diffusion limitations.
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Affiliation(s)
- Rajamani Krishna
- Van 't Hoff Institute for Molecular Sciences
- University of Amsterdam
- 1098 XH Amsterdam
- The Netherlands
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Maxwell–Stefan modeling of high flux tubular silicalite-1 membranes for CO2 removal from CO2/H2 gas mixtures. J Memb Sci 2014. [DOI: 10.1016/j.memsci.2014.08.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Lito PF, Cardoso SP, Rodrigues AE, Silva CM. Kinetic Modeling of Pure and Multicomponent Gas Permeation Through Microporous Membranes: Diffusion Mechanisms and Influence of Isotherm Type. SEPARATION AND PURIFICATION REVIEWS 2014. [DOI: 10.1080/15422119.2014.908918] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Kezia K, Lee J, Ogieglo W, Hill A, Benes NE, Kentish SE. The transport of hydronium and hydroxide ions through reverse osmosis membranes. J Memb Sci 2014. [DOI: 10.1016/j.memsci.2014.02.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Golzar K, Amjad-Iranagh S, Amani M, Modarress H. Molecular simulation study of penetrant gas transport properties into the pure and nanosized silica particles filled polysulfone membranes. J Memb Sci 2014. [DOI: 10.1016/j.memsci.2013.09.056] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Gounaris CE, First EL, Floudas CA. Estimation of diffusion anisotropy in microporous crystalline materials and optimization of crystal orientation in membranes. J Chem Phys 2013; 139:124703. [DOI: 10.1063/1.4821583] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
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Yang Q, Liu D, Zhong C, Li JR. Development of computational methodologies for metal-organic frameworks and their application in gas separations. Chem Rev 2013; 113:8261-323. [PMID: 23826973 DOI: 10.1021/cr400005f] [Citation(s) in RCA: 284] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Qingyuan Yang
- Laboratory of Computational Chemistry and State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology , Beijing 100029, China
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Krishna R, van Baten JM. Influence of adsorption thermodynamics on guest diffusivities in nanoporous crystalline materials. Phys Chem Chem Phys 2013; 15:7994-8016. [PMID: 23628965 DOI: 10.1039/c3cp50449b] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Published experimental data, underpinned by molecular simulations, are used to highlight the strong influence of adsorption thermodynamics on diffusivities of guest molecules inside ordered nanoporous crystalline materials such as zeolites, metal-organic frameworks (MOFs), and zeolitic imidazolate frameworks (ZIFs). For cage-type structures (e.g. LTA, CHA, DDR, and ZIF-8), the variation of the free energy barrier for inter-cage hopping across the narrow windows, -δFi, provides a rationalization of the observed strong influence of pore concentrations, ci, on diffusivities. In open structures with large pore volumes (e.g. FAU, IRMOF-1, CuBTC) and within channels (MFI, BEA, MgMOF-74, MIL-47, MIL-53), the pore concentration (ci) dependence of the self- (Di,self), Maxwell-Stefan (Đi), and Fick (Di) diffusivities are often strongly dictated by the inverse thermodynamic correction factor, 1/Γi≡∂ln ci/∂ln pi; the magnitudes of the diffusivities are dictated by the binding energies for adsorption. For many guest-host combinations Đi-ci dependence is directly related to the 1/Γivs. ci variation. When molecular clustering occurs, we get 1/Γi > 1, causing unusual Đivs. ci dependencies. The match, or mis-match, between the periodicity of the pore landscape and the conformations of adsorbed chain molecules often leads to non-monotonic variation of diffusivities with chain lengths.
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Affiliation(s)
- Rajamani Krishna
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
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