Helium And Hydrogen Isotope Adsorption And Separation In Metal Organic Frameworks
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Helium And Hydrogen Isotope Adsorption And Separation In Metal Organic Frameworks
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Author : Ingrid Zaiser
language : en
Publisher: Cuvillier Verlag
Release Date : 2016-10-31
Helium And Hydrogen Isotope Adsorption And Separation In Metal Organic Frameworks written by Ingrid Zaiser and has been published by Cuvillier Verlag this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-10-31 with Science categories.
The separation of isotopes has always been a challenge because of their identical size, shape and thermodynamic properties. Nowadays, the extraction of deuterium is performed e.g. by the Girdler Sulfid process or cryogenic distillation, which lead to low separation factors (below 2.5) in combination with high energy costs. The standard way to produce helium-3 is to skim it as a byproduct of the radioactive tritium decay. In this thesis, two alternative approaches have been investigated for the separation of light isotopes, Quantum Sieving and Chemical Affinity Sieving . While Quantum Sieving is based on confinement in small pores, Chemical Affinity Sieving relies on strong adsorption sites. Both methods use the mass difference of the isotopes, which is related to their zero-point energy. The microporous metal-organic frameworks are excellent candidates for studying these quantum effects due to their well-defined pore structure and the possibility to introduce strong adsorption sites directly into the framework. The samples have been exposed to an isotope mixture and the adsorbed quantity of each isotope was detected by low-temperature thermal desorption spectroscopy (TDS). The ratio of the desorbed amount of the isotopes leads directly to the selectivity (separation factor). The selectivity is determined as a function of exposure time and temperature and exhibits the highest value of 25 observed for hydrogen isotopes at temperatures well above the boiling point of liquid nitrogen.
Hydrogen Isotope Separation In Metal Organic Frameworks
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Author : Naiyuan Zhang
language : en
Publisher:
Release Date : 2018
Hydrogen Isotope Separation In Metal Organic Frameworks written by Naiyuan Zhang and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Deuterium categories.
In this thesis we present our research on hydrogen isotope separation using metal-organic frameworks (MOFs). Deuterium is one of the two stable isotopes of hydrogen. Despite its wide range of application, currently there is no ideal industrial method that can separate deuterium in a fast and efficient fashion. MOFs are a class of porous materials consisting of metal ions or clusters connected by organic ligands. They have shown great potential in separating hydrogen isotopes via quantum sieving effect. In this thesis, we first provide background on two state-of-art MOFs, Co-MOF-74 and Cu(I)-MFU-4l. Then we elaborate on the statistical theory of selectivity, the mechanism of separation and the basic idea of mass spectrometry, which is the main analytical technique used in this project. We present temperature programmed desorption (TPD) spectra for both samples. Direct separation measurement is made with Co-MOF-74. We confirm that TPD spectra can predict the results of direct separation measurements. The TPD spectra of Cu(I)-MFU-4l predict a selectivity of approximately 6 at easily accessible temperatures (~260K). This shows the practicality of using Cu(I)-MFU-4l for hydrogen isotope separation. Preferential adsorption separation is also performed with Co-MOF-74. The extracted activation energy agrees to within 10% of literature predictions based on quantum zero point energy models.
A Gas Flow Through System For Hydrogen Isotopic Separation With Metal Organic Frameworks
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Author : Katharine Harp Rigdon
language : en
Publisher:
Release Date : 2019
A Gas Flow Through System For Hydrogen Isotopic Separation With Metal Organic Frameworks written by Katharine Harp Rigdon and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019 with Carbon dioxide categories.
In this thesis, we designed and built a gas flow-through system to study dynamic adsorption separation of hydrogen isotopes in metal-organic frameworks (MOFs). MOFs are porous, crystalline materials composed of metal complexes connected by organic linkers. They have been proposed as a cheaper, more energy efficient approach to hydrogen isotope separation than current industrial methods. We have previously found evidence of a zero-point energy-based separation mechanism for hydrogen isotopes in two MOFs: Co-MOF-74 and Cu(I)-MFU-4l. This mechanism, chemical affinity quantum sieving (CAQS), has been extensively studied under static equilibrium conditions. The system in this work was developed so that CAQS could be studied under dynamic conditions that more closely resemble those in industrial separation. Breakthrough analysis is an established technique for studying dynamic separation in porous materials. Generally, a breakthrough experiment involves flowing a gas mixture through a fixed bed of adsorbent material and measuring the composition of the effluent flow. In this work, a 1:1 mixture of common hydrogen and its isotope deuterium was flowed through 71 mg of Co-MOF-74 or 22 mg of Cu(I)-MFU-4l. A quadrupole mass spectrometer was used to monitor the composition of the effluent flow. We saw preferential adsorption of deuterium over common hydrogen in Co-MOF-74 at 77K and Cu(I)-MFU-4l at 170K, 140K, and 110K. This behavior was absent in Cu(I)-MFU-4l at 77K, a phenomenon that we would like to investigate further. Minimal adsorption occurred in both MOFs at room temperature, as expected. A selectivity of deuterium over common hydrogen was calculated for each temperature. These selectivities were approximately 30% lower than comparable literature values. Our goal is to make improvements to our system and methods to measure the selectivity more accurately and reproducibly. Notably, all measured selectivities were higher than the selectivity of the Girdler Sulfide method and cryogenic distillation, two industrial hydrogen isotope separation processes we are trying to improve on. This new system gives us the capability to study dynamic adsorption and kinetic separation of hydrogen isotopes in metal-organic frameworks going forward. We hope that our work will inform the development of efficient, environmentally sustainable separation processes.
Capture Of Heavy Hydrogen Isotopes In A Metal Organic Framework With Active Cu I Sites
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Author :
language : en
Publisher:
Release Date : 2017
Capture Of Heavy Hydrogen Isotopes In A Metal Organic Framework With Active Cu I Sites written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
The production of pure deuterium and the removal of tritium from nuclear waste are the key challenges in separation of light isotopes. Presently, the technological methods are extremely energy- and cost-intensive. Here we report the capture of heavy hydrogen isotopes from hydrogen gas by selective adsorption at Cu(I) sites in a metal-organic framework. At the strongly binding Cu(I) sites (32 kJ mol-1) nuclear quantum effects result in higher adsorption enthalpies of heavier isotopes. The capture mechanism takes place most efficiently at temperatures above 80 K, when an isotope exchange allows the preferential adsorption of heavy isotopologues from the gas phase. Large difference in adsorption enthalpy of 2.5 kJ mol-1 between D2 and H2 results in D2-over-H2 selectivity of 11 at 100 K, to the best of our knowledge the largest value known to date. Combination of thermal desorption spectroscopy, Raman measurements, inelastic neutron scattering and first principles calculations for H2/D2 mixtures allows the prediction of selectivities for tritium-containing isotopologues.
Hydrogen And Helium Recycling At Plasma Facing Materials
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Author : Ahmed Hassanein
language : en
Publisher: Springer Science & Business Media
Release Date : 2002-03-31
Hydrogen And Helium Recycling At Plasma Facing Materials written by Ahmed Hassanein and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002-03-31 with Mathematics categories.
Proceedings of the NATO Advanced Research Workshop on Hydrogen Isotope Recycling at Plasma Facing Materials in Fusion Reactors, Argonne, Illinois, USA from 22-24 August 2001
Wasserstoffadsorption In Metall Organischen Ger Ststoffen
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Author : Barbara Streppel
language : en
Publisher:
Release Date : 2011
Wasserstoffadsorption In Metall Organischen Ger Ststoffen written by Barbara Streppel and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
Adsorption On Mesoporous Metal Organic Frameworks In Solution For Clean Energy Environment And Healthcare
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Author : Alexander Samokhvalov
language : en
Publisher: CRC Press
Release Date : 2017-04-07
Adsorption On Mesoporous Metal Organic Frameworks In Solution For Clean Energy Environment And Healthcare written by Alexander Samokhvalov and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-04-07 with Technology & Engineering categories.
Adsorption and desorption in solution play significant roles in separations, detoxification of waste streams, in purification, chromatography, heterogeneous catalysis, metabolism of medicinal drugs, and beyond. Metal-Organic Frameworks (MOFs) are well-ordered 3-dimensional hybrid organic-inorganic polymers which contain metal cations and the structure-building organic "linker" units. Mesoporous MOFs with pore sizes 2-50 nm are particularly suitable for adsorption and adsorption-based separations of large molecules of organic and bio-organic compounds. Thousands of organic compounds and, in particular, aromatic and heterocyclic compounds are widely used as feedstock for industrial chemical synthesis, as fine chemicals, major components of liquid fossil fuels, dyestuffs, industrial solvents, agricultural chemicals, medicinal drugs, pharmaceuticals and personal care products (PPCPs), and active pharmaceutical ingredients (APIs). There is a strong interest towards synthesis, characterization and studies of both known and newly synthesized mesoporous MOFs for adsorption in solution to achieve the high adsorption capacity, selectivity, and the possibility of multiple regeneration of "spent" sorbent. This book covers experimental fundamental research on using mesoporous MOFs in emerging applications of major industrial, environmental and academic importance, especially purification of water and liquid fossil fuels and in advanced biomedical technologies.
Interaction Of Hydrogen Isotopes With Flexible Metal Organic Frameworks
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Author : Linda Bondorf
language : en
Publisher:
Release Date : 2020
Interaction Of Hydrogen Isotopes With Flexible Metal Organic Frameworks written by Linda Bondorf and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.
First Principle Investigations Of Hydrogen Adsorption In Metal Organic Framework 5
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Author : Muhammad Hafiz Hussim
language : en
Publisher:
Release Date : 2013
First Principle Investigations Of Hydrogen Adsorption In Metal Organic Framework 5 written by Muhammad Hafiz Hussim and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Adsorption categories.
Metal Organic Frameworks
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Author : Victoria Samanidou
language : en
Publisher: MDPI
Release Date : 2020-03-27
Metal Organic Frameworks written by Victoria Samanidou and has been published by MDPI this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-03-27 with Science categories.
Metal–organic frameworks are among the most promising novel materials. The concept of MOFs was first introduced in 1990. They were actually initially used in catalysis, gas separation, membranes, electrochemical sensors. Later on, they were introduced as SPE sorbents for PAHs (Polycyclic Aromatic Hydrocarbons) in environmental water samples, then the range expanded to the field of analytical chemistry, both in chromatographic separation and sample preparation, with great success in, e.g., SPE and SPME (Solid Phase Mico-extraction). Since then, the number of analytical applications implementing MOFs as sorbents in sorptive sample preparation approaches is increasing. Τhis is reinforced by the fact that, at least theoretically, an infinite number of structures can be designed and synthesized, thus making tuneability one of the most unique characteristics of MOF materials. Moreover, they have been designed in various shapes, such as columns, fibers, and films, so that they can meet more analytical challenges with improved analytical features.Their exceptional properties attracted the interest of analytical chemists who have taken advantage of the unique structures and properties and have already introduced them in several sample pretreatment techniques, such as solid phase extraction, dispersive SPE, magnetic solid phase extraction, solid phase microextraction, stir bar sorptive extraction, etc.
