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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.
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.
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.
Metal-Organic Frameworks (MOFs) are crystalline compounds consisting of rigid organic molecules held together and organized by metal ions or clusters. Special interests in these materials arise from the fact that many are highly porous and can be used for storage of small molecules, for example H2 or CO2. Consequently, the materials are ideal candidates for a wide range of applications including gas storage, separation technologies and catalysis. Potential applications include the storage of hydrogen for fuel-cell cars, and the removal and storage of carbon dioxide in sustainable technical processes. MOFs offer the inorganic chemist and materials scientist a wide range of new synthetic possibilities and open the doors to new and exciting basic research. Metal-Organic Frameworks Materials provides a solid basis for the understanding of MOFs and insights into new inorganic materials structures and properties. The volume also reflects progress that has been made in recent years, presenting a wide range of new applications including state-of-the art developments in the promising technology for alternative fuels. The comprehensive volume investigates structures, symmetry, supramolecular chemistry, surface engineering, recognition, properties, and reactions. The content from this book will be added online to the Encyclopedia of Inorganic and Bioinorganic Chemistry: http://www.wileyonlinelibrary.com/ref/eibc
The third edition of the Handbook of Membrane Separations: Chemical, Pharmaceutical, Food, and Biotechnological Applications provides a comprehensive discussion of membrane applications. Fully updated to include the latest advancements in membrane science and technology, it is a one-of-its-kind overview of the existing literature. This fully illustrated handbook is written by experts and professionals in membrane applications from around the world. Key Features: Includes entirely new chapters on organic solvent-resistant nanofiltration, membrane condensers, membrane-reactors in hydrogen production, membrane materials for haemodialysis, and integrated membrane distillation Covers the full spectrum of membrane technology and its advancements Explores membrane applications in a range of fields, from biotechnological and food processing to industrial waste management and environmental engineering This book will appeal to both newcomers to membrane science as well as engineers and scientists looking to expand their knowledge on upcoming advancements in the field.
Advanced Structural Chemistry Discover the relationships between inorganic chemical synthesis, structure, and property with these comprehensive and insightful volumes Advanced Structural Chemistry: Tailoring Properties of Inorganic Materials and their Applications (3 Volume Set) offers readers the opportunity to discover the relationship between the structure and function of matter, develop efficient and precise synthesis methodology, and to understand the theoretical tools for new functional substances. Advanced Structural Chemistry clarifies the relationships between synthesis and structure, as well as structure and property, both of which are central to the creation of new materials with unique functions. In addition to subjects like the syntheses of metal-oxide clusters, metal-organic cages, and metal-organic frameworks with tailored optical, electric, ferroelectric, magnetic, adsorption, separation, and catalytic properties, the accomplished editor Rong Cao provides readers with information on a wide variety of topics, such as: Coordination-assembled metal-organic macrocycles and cages, including metallacycles and metallacages The structural chemistry of metal-oxo clusters, including the oxo clusters of transition metal, main group metal, and lanthanides Synthetic approaches, structural diversities, and biological aspects of molybdenum-based heterometallic sulfide clusters and coordination polymers Group 11-15 metal chalcogenides, including discrete chalcogenide clusters synthesized in ionic liquids The structures of metal-organic frameworks, including one-, two-, and three-dimensional MOFs Perfect for inorganic chemists, structural chemists, solid state chemists, material scientists, and solid state physicists, Advanced Structural Chemistry also belongs on the bookshelves of catalytic and industrial chemists who seek to improve their understanding of the structure and functions of inorganic materials.
Adsorption, Ion Exchange and Catalysis is essentially a mixture of environmental science and chemical reactor engineering. More specifically, three important heterogeneous processes, namely, adsorption, ion exchange and catalysis, are analysed, from fundamental kinetics to reactor design with emphasis on their environmental applications. In Chapter 1, the subject of air and water pollution is dealt with. Data about pollutants and emission sources are given and the treatment methods are shortly presented. In Chapter 2, the very basics and historical development of adsorption, ion exchange and catalysis are presented as well as their environmental applications. Chapter 3 is devoted to heterogeneous processes and reactor analysis. All types of reactors are described in depth and reactor modelling, hydraulics and mass/heat transfer phenomena are examined for each type of reactor. Chapters 4 and 5 are dedicated to adsorption & ion exchange and catalysis, respectively. The basic principles are presented including kinetics, equilibrium, mass/heat transfer phenomena as well as the analytical solutions of the reactor models presented in Chapter 3. In the sixth chapter, the subject of scale up is approached. The two Annexes at the end of the book contain physical properties of substances of environmental interest as well as unit conversion tables. Finally, nearly all the examples contained are based on real experimental data found in literature with environmental interest. Most of the examples consider all aspects of operation design – kinetics, hydraulics and mass transfer.* Provides basic knowledge of major environmental problems and connects them to chemical engineering
A study was made of the properties of metal hydrides which may be suitable for use in chromatographic separation of hydrogen isotopes. Sixty-five alloys were measured, with the best having a hydrogen-deuterium separation factor of 1.35 at 60°C. Chromatographic columns using these alloys produced deuterium enrichments of up to 3.6 in a single pass, using natural abundance hydrogen as starting material. 25 references, 16 figures, 4 tables.