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1
Taksande, Kiran. "Exploration of the Ionic Conduction Properties of Porous MOF Materials." Thesis, Université de Montpellier (2022-….), 2022. http://www.theses.fr/2022UMONS010.
Full textAbstract:
Ce travail a pour objectif l’étude de matériaux hybrides poreux de type Metal-Organic Frameworks (MOFs) et d’un cristal moléculaire en tant que conducteurs ioniques solides pour des applications dans le domaine de l’énergie et de l’environnement. Dans le premier cas, nous avons développé diverses stratégies pour optimiser et contrôler la teneur en sites acides de Lewis et en porteurs de charges de deux séries de MOFs afin de concevoir des matériaux aux propriétés de conduction protonique très prometteuses. A partir d’une approche basée sur la substitution progressive des ligands par des entités fonctionnalisées présentant des sources de protons acides, nous avons créé une série de MOFs, MIP-207-(SO3H-IPA)x-(BTC)1–x, dont la teneur en groupements sulfoniques, par l’intermédiaire du ligand SO3H-IPA, est contrôlée à façon. Le meilleur matériau qui combine stabilité structurale et conduction protonique élevée présente des performances sous humidité parmi les plus intéressantes au sein de la famille des MOFs conducteurs protoniques (e.g., σ = 2.6 × 10–2 S cm–1 à 363 K/95% d’humidité relative (RH)). Selon une autre approche, nous avons étudié un MOF mésoporeux connu (MIL-101(Cr)-SO3H) dont les parois des pores sont tapissées de sites protoniques et qui contient dans ses pores un liquide ionique, le chlorure chlorure de 1-Ethyl-3-methylimidazolium (EMIMCl) capable d’assurer le transfert de proton. L’encapsulation du liquide ionique, caractérisée par une série d’outils expérimentaux (sorption de diazote, DRX sur poudre, TGA/MS, DSC et analyse élémentaire), s’avère particulièrement efficace pour exalter les propriétés de conduction protonique des composites à la fois à l’état anhydre (σ473 K = 1.5 × 10-3 S cm-1) mais également à l’état hydraté (σ(343 K/60%-80%RH) ≥ 0.10 S cm-1). Enfin, ce travail a été étendu à une autre famille de solides poreux, à travers l’étude des propriétés de conduction ionique d’un cristal moléculaire à base de zirconium (Zr-3) qui contient des paires ioniques KCl. Nous avons démontré que ZF-3 transite d’un comportement isolant à l’état anhydre (σ = 5.1 x 10-10 S cm-1 à 363 K/0% RH) vers un comportement super-conducteur ionique en présence d’eau (σ = 5.2 x 10-2 S cm-1 à 363 K/95 % RH), suite à l’augmentation de la dynamique de ions Cl- sous hydratation. Par ailleurs, des simulations moléculaires ont permis de décrire les mécanismes microscopiques à l’origine des propriétés de conduction des matériaux étudiés. Ces avancées devraient permettre de développer dans le futur de nouveaux matériaux performants dans le domaine de la conduction protonique et ioniqueThe conductivity performance of a new series of chemically stable proton conducting Metal Organic Frameworks (MOFs) as well as a superionic molecular crystal was explored. The contribution of this PhD was to (i) select a variety of architectures and functionalities of robust MOFs/superionic molecular solids and (ii) characterize and rationalize their conducting performance over various temperature/humidity conditions. We designed two series of MOFs to achieve promising proton-conducting performance, using distinct approaches to modulate the concentration of Brønsted acidic sites and charge carriers and further boost the conductivity properties. First, a multicomponent ligand replacement strategy was successfully employed to elaborate a series of multivariate sulfonic-based solids MIP-207-(SO3H-IPA)x-(BTC)1–x which combine structural integrity with high proton conductivity values (e.g., σ = 2.6 × 10–2 S cm–1 at 363 K/95% Relative Humidity -RH-). Secondly, a proton conducting composite was prepared through the impregnation of an ionic liquid (1-Ethyl-3-methylimidazolium chloride, EMIMCl) in the mesoporous MIL-101(Cr)-SO3H. The resulting composite displaying high thermal and chemical stability, exhibits outstanding proton conductivity not only at the anhydrous state (σ473 K = 1.5 × 10-3 S cm-1) but also under humidity (σ(343 K/60%-80%RH) ≥ 0.10 S cm-1) conditions. Finally, the ionic conducting properties of another class of porous solids, considering a zirconium-formate molecular solid containing KCl ion pairs (ZF-3) were explored. ZF-3 switches from an insulator (σ = 5.1 x 10-10 S cm-1 at 363 K/0% RH) to a superionic conductor upon hydration (σ = 5.2 x 10-2 S cm-1 at 363 K/95 % RH), in relation with the boost of Cl- dynamics upon water adsorption. Noteworthy, quantum- and force-field based simulations were combined with the experimental approach to elucidate the microscopic mechanisms at the origin of the ionic conducting properties of the studied materials. This fundamental knowledge will serve to create novel robust superionic conductors with outstanding performances that will pave the way towards appealing societal applications for clean energy production
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Taksande, Kiran. "Exploration of the Ionic Conduction Properties of Porous MOF Materials." Thesis, Montpellier, 2022. https://ged.scdi-montpellier.fr/florabium/jsp/nnt.jsp?nnt=2022UMONS010.
Full textAbstract:
Ce travail a pour objectif l’étude de matériaux hybrides poreux de type Metal-Organic Frameworks (MOFs) et d’un cristal moléculaire en tant que conducteurs ioniques solides pour des applications dans le domaine de l’énergie et de l’environnement. Dans le premier cas, nous avons développé diverses stratégies pour optimiser et contrôler la teneur en sites acides de Lewis et en porteurs de charges de deux séries de MOFs afin de concevoir des matériaux aux propriétés de conduction protonique très prometteuses. A partir d’une approche basée sur la substitution progressive des ligands par des entités fonctionnalisées présentant des sources de protons acides, nous avons créé une série de MOFs, MIP-207-(SO3H-IPA)x-(BTC)1–x, dont la teneur en groupements sulfoniques, par l’intermédiaire du ligand SO3H-IPA, est contrôlée à façon. Le meilleur matériau qui combine stabilité structurale et conduction protonique élevée présente des performances sous humidité parmi les plus intéressantes au sein de la famille des MOFs conducteurs protoniques (e.g., σ = 2.6 × 10–2 S cm–1 à 363 K/95% d’humidité relative (RH)). Selon une autre approche, nous avons étudié un MOF mésoporeux connu (MIL-101(Cr)-SO3H) dont les parois des pores sont tapissées de sites protoniques et qui contient dans ses pores un liquide ionique, le chlorure chlorure de 1-Ethyl-3-methylimidazolium (EMIMCl) capable d’assurer le transfert de proton. L’encapsulation du liquide ionique, caractérisée par une série d’outils expérimentaux (sorption de diazote, DRX sur poudre, TGA/MS, DSC et analyse élémentaire), s’avère particulièrement efficace pour exalter les propriétés de conduction protonique des composites à la fois à l’état anhydre (σ473 K = 1.5 × 10-3 S cm-1) mais également à l’état hydraté (σ(343 K/60%-80%RH) ≥ 0.10 S cm-1). Enfin, ce travail a été étendu à une autre famille de solides poreux, à travers l’étude des propriétés de conduction ionique d’un cristal moléculaire à base de zirconium (Zr-3) qui contient des paires ioniques KCl. Nous avons démontré que ZF-3 transite d’un comportement isolant à l’état anhydre (σ = 5.1 x 10-10 S cm-1 à 363 K/0% RH) vers un comportement super-conducteur ionique en présence d’eau (σ = 5.2 x 10-2 S cm-1 à 363 K/95 % RH), suite à l’augmentation de la dynamique de ions Cl- sous hydratation. Par ailleurs, des simulations moléculaires ont permis de décrire les mécanismes microscopiques à l’origine des propriétés de conduction des matériaux étudiés. Ces avancées devraient permettre de développer dans le futur de nouveaux matériaux performants dans le domaine de la conduction protonique et ioniqueThe conductivity performance of a new series of chemically stable proton conducting Metal Organic Frameworks (MOFs) as well as a superionic molecular crystal was explored. The contribution of this PhD was to (i) select a variety of architectures and functionalities of robust MOFs/superionic molecular solids and (ii) characterize and rationalize their conducting performance over various temperature/humidity conditions. We designed two series of MOFs to achieve promising proton-conducting performance, using distinct approaches to modulate the concentration of Brønsted acidic sites and charge carriers and further boost the conductivity properties. First, a multicomponent ligand replacement strategy was successfully employed to elaborate a series of multivariate sulfonic-based solids MIP-207-(SO3H-IPA)x-(BTC)1–x which combine structural integrity with high proton conductivity values (e.g., σ = 2.6 × 10–2 S cm–1 at 363 K/95% Relative Humidity -RH-). Secondly, a proton conducting composite was prepared through the impregnation of an ionic liquid (1-Ethyl-3-methylimidazolium chloride, EMIMCl) in the mesoporous MIL-101(Cr)-SO3H. The resulting composite displaying high thermal and chemical stability, exhibits outstanding proton conductivity not only at the anhydrous state (σ473 K = 1.5 × 10-3 S cm-1) but also under humidity (σ(343 K/60%-80%RH) ≥ 0.10 S cm-1) conditions. Finally, the ionic conducting properties of another class of porous solids, considering a zirconium-formate molecular solid containing KCl ion pairs (ZF-3) were explored. ZF-3 switches from an insulator (σ = 5.1 x 10-10 S cm-1 at 363 K/0% RH) to a superionic conductor upon hydration (σ = 5.2 x 10-2 S cm-1 at 363 K/95 % RH), in relation with the boost of Cl- dynamics upon water adsorption. Noteworthy, quantum- and force-field based simulations were combined with the experimental approach to elucidate the microscopic mechanisms at the origin of the ionic conducting properties of the studied materials. This fundamental knowledge will serve to create novel robust superionic conductors with outstanding performances that will pave the way towards appealing societal applications for clean energy production
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Yeates, Rachel Marie. "Photoreactivity of porous metal-oxide frameworks." Thesis, University of Aberdeen, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.415549.
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The photoreactivity of three different types of porous metal-oxide frameworks have been investigated. The porous metal-oxide frameworks assessed are germanate, titanosilicate and vanadosilicate materials. A number of materials were synthesised, ASU-7, AUG-1, AUG-2, NH4-Ge-PHA, Li-ex-Ge-PHA. Mesoporous germanates, K-Ti-Si-PHA, AM-6 and ETVS-10. All materials synthesised were characterised using a number of techniques; x-ray diffraction, electron microscopy, solid state NMR, FT-IR, Raman, UV-vis, EXAFS, XPS, TGA and DTA. The photoreactivity of selected materials were investigated using EPR spectroscopy. The photoreactivity of two forms of the germanate pharmacosiderite material (NH4Ge-PHA and Li-ex-Ge-PHA) was explored. These materials are shown to have limited potential as photocatalyst due to their limited photoreactivity and their low thermal stability. However, on comparison to the non-porous metal oxide (h-GeO2) an improvement in photoreactivity was observed. The titanosilicate material showed limited photoreduction in the presence of ethene and methanol. However, when irradiated in the presence of oxygen a relatively stable and intense mononuclear O- species is formed. This species is found as a result of positive holes trapped at lattice oxide ions. A trapped hole signal with this stability has not previously been reported. AM-6 is shown to be a fully substituted vanadium form of ETS-10. The vanadium present is vanadium (IV) ions in octahedral coordination linking to form V-O chains. EXAFS analysis shows that the vanadium is in fact in significantly distorted octahedral sites. It is also shown that the free electrons are delocalised along the length of the vanadium-oxygen chains within the structure. ETVS-10 is a partially substituted vanadium form of ETS-10. The vanadium-oxygen chains present are interrupted by titanium sites, resulting in a reduction of the delocalisation of electrons along the chains. A photoreactivity study of these materials was problematical due to the intensity of the vanadium (IV) signal this made analysis of changes occurring upon irradiation in oxygen and methanol complicated.
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Hellman, Oskar. "Synthesis of framework porous sorbents using sustainable precursors." Thesis, Uppsala universitet, Nanoteknologi och funktionella material, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-445896.
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Metal organic frameworks (MOFs) is a quite recently discovered porous material group which shows potential in many different areas. One of these areas is carbon capture; the framework structure of the porous materials allows gas molecules to adsorb to the surface of the pores. MOFs are conventionally synthesised at high temperatures and with hazardous solvents. The goal of this projectwas to synthesise highly porous MOFs at room temperature with water as the main solvent, using environmentally friendly and non-hazardous precursors. As well as the room temperature synthesis, conventional synthesis methods were used with the same precursors as comparison. The materials were characterised with X-ray diffraction, thermogravimetrical methods and IR-spectroscopy. To assess the porosity of the materials, gas adsorption evaluation was performed with CO2, N2, SF6, and CH4 at 20⁰C. In the end, three novel porous magnesium-based materials and one zirconium-based material were successfully synthesised. One of the magnesium-based materials showed a moderately high CO2 adsorption (2.38mmol/g), and could be synthesised at room temperature. The zirconium-based material showed a remarkably high selectivity (17.7) for SF6 over N2 and a high surface area (550m2/g)
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Yu, Jierui. "PHOTOPHYSICS OF CHROMOPHORE ASSEMBLIES IN POROUS FRAMEWORKS." OpenSIUC, 2021. https://opensiuc.lib.siu.edu/dissertations/1926.
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Chromophore is a molecule or a part of a molecule which is responsible for its appearance color. This definition has been evolving over time with the progress of science. Contemporary scientific advances have expanded its meaning: to an inclusive level, chromophore is an irreducible collective of fundamental particles, which can represent the photophysical (optical physical) properties of the macroscopic matter. Previous studies have already found that the same molecule can have different photophysical properties under different condensed states. Therefore, it is straight forward to conclude that the definition of chromophore should take such extrinsic influencing interactions of this given molecule into consideration, thus simply taking the smallest unit such as a molecule is not accurate. A good example is quantum dots. Same species of quantum dots possess the identical smallest chemical unit but can emit very differently due to quantum confinement effect, thus defining the smallest unit as the chromophore is apparently fallacious. In solid polymeric compositions, the chemical unit or building blocks may differ from the spectroscopic unit depending on how these chemical units interacts within their ensemble to evolve new properties such as a new transition dipole. As thus, understanding the evolution of photophysical behaviors between the targeted unit and neighbors is of much importance to determine whether they should be considered as one chromophore or many. This requires a thorough understanding towards the evolution of photophysical properties of a collective, and the construction of such collective will need to pay extra attention to, as any structural factor could have changed some photophysical interactions of the collective. The introductory chapter discusses the material platform and fundamental photophysics investigated in this dissertation. Chromophore assembly (CA) as a sylloge of several classes of self-assembled materials, including metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), porous organic polymers (POPs). Among them, MOF-based CAs (MOF-CAs) featuring with the ease of synthesis, demonstrate incomparable promises to construct such collective with several appealing characteristics, including component diversity, chemical stability, structural porosity, and post-synthetic versatility (Chapter 1.1). As for here, the main target to achieve using these assemblies is to understand the interaction between adjacent chemical monomeric units, therefore their spatial arrangements are of the paramount importance. As modern theory discovered, both ordered and random systems can be very important for novel quantum material developments. Both crystalline and amorphous arrangements of monomeric units can be achieved by adopting different classes of materials. MOF-CAs could achieve the precise control of spatial arrangement including distance, direction, and dihedral angle by its crystalline structures, whereas porous organic polymer-based CAs (POP-CAs) could feature a total randomness. Photophysics, as the research topic targeting the firsthand knowledge gained by interrogating the information provided by the propagating light after its interaction with matters, could provide crucial knowledge of the targeted matter. Hence, photophysical properties could provide fundamental understanding of the targeted matter (Chapter 1.2). State-of-the-art spectroscopic methods and instrumentation have made it possible to critically examine new structures to correlate photophysics with the chemical structure of their assemblies. By combining multiple spectroscopic techniques along with theoretical study, several correlations between the electronic properties of the matter, such as structural features, have been investigated. To illustrate, some unique topology-dependent photophysical behaviors found in chromophore assemblies are introduced (Chapter 1.3). In this dissertation, the feasibility of using specific types of MOF-CAs to conduct unique photophysical studies has been carefully chosen and verified (Chapter 2). Next, with the help of first principles computations, the nature of several electronic excited states as a function of different extent of Van der Waals or electronic interaction in MOF-CAs is unveiled, and experimentally studied with several environmental variates (Chapter 3). The knowledge was then articulated to devise a strategy to improve resonance energy transfer process in MOF-CAs. Here, low electronic symmetry of linker and directionally aligned transition dipoles of their collective ensembled are found beneficial to improve such photophysical process in a bottom-up manner (Chapter 4). Then, a series of MOFs were rationally designed to examine the feasibility and extent of a nonlinear excitonic process, singlet fission, to promote the generation of carriers usable for many applications including light-harvesting applications. The outcome demonstrated MOF-CA is a powerful tool to design such materials and is more capable in terms of its tunability (Chapter 5). At last, a set of randomly oriented CAs in POP were examined for underlying excited state dynamic process that highlights a thermal activated delayed fluorescence (TADF) involving S1 and low-lying T2 excited states (Chapter 6). This dissertation has highlighted unique yet tunable excited-state features and photophysical processes within the well-defined molecular ensemble realized via porous frameworks. These photophysical properties differ from those of their respective molecular system in their solubilized forms. Studies in this dissertation demonstrates a reliable platform to investigate multibody chromophore systems and suggested several valuable discoveries and lights the way for the study of novel chromophore assembly systems.
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Haque, Md Enamul. "Synthesis of porous carbon and porous graphene from metal-organic framework and their electrochemical properties." Thesis, The University of Sydney, 2014. http://hdl.handle.net/2123/13261.
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One non porous MOF (MOF-235) and one highly porous MOF (amino-MIL-101) were synthesized as starting precursors to get carbon materials by using these MOFs as template and also by direct carbonization. The application of aminofunctionalized MOF was also investigated for water purification. Harmful dyes (both cationic and anionic dyes) can be efficiently removed from contaminated water by the amino-functionalised MOF, amino-MIL-101(Al). This MOF showed a superior adsorption capacity to remove cationic dyes than any other MOFs reported in the literature. Nanoporous graphenes with high surface area were synthesized using a metal-organic framework (non porous MOF) a template with furfuryl alcohol as well as by direct carbonization technique. This new synthesis technique is very simple and one step process to get nanoporous graphene. The graphene synthesized by this process showed excellent electrochemical properties as an electrode materials for electric double layer capacitor. The capacitor made up with this nanoporous graphene displayed excellent capacity retention over 10000 cycles. On the other hand, highly porous N-doped carbons were synthesized by carbonizing an amino-functionalized metalorganic framework (porous MOF) using a template with furfuryl alcohol as well as by the direct carbinization. A series of N-doped porous carbon were investigated to examine its electrocatalytic properties based on different nitrogen sites. A particular nitrogen type containing carbon materials shows an activity as excellent electrocatalyst among the different types of N functionalities including pyrrolic N, pyridinic N, quaternary N and pyridinic N-oxide. This allowed the impact of quaternary N on the electrocatalytic activity for oxygen reduction to be assessed in a series of related N-doped carbons. Only the quaternary-N-containing N-doped carbon catalyzed the four-electron reduction of O2, offering insight into the active site for reaction. This synthesized highly porous N-doped porous carbon also displayed remarkable capacitance properties as double layer capacitor than non doped porous carbon reported in the literature. The capacitor made up with this nanoporous carbon displayed poor capacity retention over 5000 cycles compared with porous graphene.
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Ma, Shengqian. "Gas Adsorption Applications of Porous Metal-Organic Frameworks." Miami University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=miami1209411394.
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Grünker, Ronny, Irena Senkovska, Ralf Biedermann, Nicole Klein, Martin R. Lohe, Philipp Müller, and Stefan Kaskel. "A highly porous flexible Metal–Organic Framework with corundum topology." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-138599.
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A flexible Metal–Organic Framework Zn4O(BenzTB)3/2 (DUT-13) was obtained by combination of a tetratopic linker and Zn4O6+ as connector. The material has a corundum topology and shows the highest pore volume among flexible MOFsDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Grünker, Ronny, Irena Senkovska, Ralf Biedermann, Nicole Klein, Martin R. Lohe, Philipp Müller, and Stefan Kaskel. "A highly porous flexible Metal–Organic Framework with corundum topology." Royal Society of Chemistry, 2011. https://tud.qucosa.de/id/qucosa%3A27762.
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A flexible Metal–Organic Framework Zn4O(BenzTB)3/2 (DUT-13) was obtained by combination of a tetratopic linker and Zn4O6+ as connector. The material has a corundum topology and shows the highest pore volume among flexible MOFs.Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Abdelhamid, Hani Nasser. "Lanthanide Metal-Organic Frameworks and Hierarchical Porous Zeolitic Imidazolate Frameworks : Synthesis, Properties, and Applications." Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-146398.
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This thesis presents the synthesis, properties, and applications of two important classes of metal-organic frameworks (MOFs); lanthanide MOFs and hierarchical porous zeolitic imidazolate frameworks (ZIFs). The materials have been characterized using a wide range of techniques including diffraction, imaging, various spectroscopic techniques, gas sorption, dynamical light scattering (DLS) and thermogravimetric analysis (TGA). In Chapter 1, the unique features of MOFs and ZIFs as well as their potential applications are summarized. In Chapter 2, different characterization techniques are presented. Chapter 3 describes a family of new isoreticular lanthanide MOFs synthesized using tri-topic linkers of different sizes, H3L1-H3L4, denoted SUMOF-7I-IV (Ln) (SU; Stockholm University, Ln = La, Ce, Pr, Nd, Sm, Eu and Gd, Paper I). The SUMOF-7I-III (Ln) contain permanent pores and exhibit exceptionally high thermal and chemical stability. The luminescence properties of SUMOF-7IIs are reported (Paper II). The influences of Ln ions and the tri-topic linkers as well as solvent molecules on the luminescence properties are investigated. Furthermore, the potential of SUMOF-7II (La) for selective sensing of Fe (III) ions and the amino acid tryptophan is demonstrated (Paper III). Chapter 4 presents a simple, fast and scalable approach for the synthesis of hierarchical porous zeolitic imidazolate framework ZIF-8 and ZIF-67 using triethylamine (TEA)-assisted approach (Paper IV). Organic dye molecules and proteins are encapsulated directly into the ZIFs using the one-pot method. The photophysical properties of the dyes are improved through the encapsulation into ZIF-8 nanoparticles (Paper IV). The porosity and surface area of the ZIF materials can be tuned using the different amounts of dye or TEA. To further simplify the synthesis of hierarchical porous ZIF-8, a template-free approach is presented using sodium hydroxide, which at low concentrations induces the formation of zinc hydroxide nitrate nanosheets that serve as in situ sacrificial templates (Chapter 5, Paper V). A 2D leaf-like ZIF (ZIF-L) is also obtained using the method. The hierarchical porous ZIF-8 and ZIF-L show good performance for CO2 sorption.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 5: Manuscript.
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Stackhouse, Chavis Andrew. "Azamacrocyclic-based Frameworks: Syntheses and Characterizations." Scholar Commons, 2018. https://scholarcommons.usf.edu/etd/7646.
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Research in metal-organic frameworks (MOFs) has risen greatly in recent decades Owing to their unequaled potential tunability and structural diversity. MOFs may be described as crystalline structures composed of metal cations or clusters of cations, commonly referred to as secondary building units (SBUs), and custom-designed organic ligands. The variety of structural motifs, ligands, and SBUs that may be incorporated promote the attainment of essentially countless potential MOFs and application in numerous areas of interest, such as gas adsorption, catalysis, gas separation, and sensing. Further functionalization of MOF materials by means of post-synthetic modification(PSM)33–37 of metal clusters or organic ligands, constructing frameworks using functional ligands or metal clusters, and incorporating advantageous molecules including organometallic molecules,38–41 enzymes,42–45 metal nanoparticles (NPs),8,46–48 heteropolyacids49–51 within the pores advance the diverse number of species, including organic ligands, inorganic metal ions/clusters, and guests, used to construct MOFs materials lead to MOFs materials possessing phenomenal properties. Implementation of these materials in sensing arises from the frameworks’ characteristic ability to increase the concentration of a desired analyte to a greater degree than its overall presence within the system; imparting an inherent sensitivity to the aforementioned analyte. MOFs materials also possess the potential for selectivity for specific analytes or classes of analytes through mechanisms such as size exclusion (molecular sieving), chemically specific interactions between the adsorbate and framework, and the directed design of pore and aperture size through the selection of appropriate organic linkers or struts.
Flexible azamacrocycle-based ligands are constructed through the use of pliable carboxylate pendant arms and azamacrocycles, e.g cyclen and tacn, and used in the pursuit of novel metal macrocycle frameworks (MMCF). Polyazamacrocycles represent a popular class of macrocyclic ligands for supramolecular chemistry and crystal engineering. This popularity may be due to their complexes’ high thermodynamic stability, relative kinetic inertness, basicity, transition metal-ion coordinating ability and rigid structure. Furthermore, their utilization promotes intriguing network topologies as coordination in complexes containing tetradentate azamacrocycles generally produces only two isomers differing via the coordination ligand’s conformation. The highly reported equatorial N4¬ ¬coordination of the macrocycle allows for interaction at the two vacant trans-axial positons, whilst the folded conformations permits interaction at two vacant cis positions. Azamacrocycle complexes differ from those of other classes of macrocycles due to the fact the macrocyclic cavity is commonly occupied by metal cations. Materials containing azamacrocycles have found use in applications such as bleaching and oxidative catalysis and molecular recognition. Cyclen units have reportedly been incorporated to construct pH-dependent selective receptors for copper (II), zinc(II), yttrium(III), and lanthanum(III) ions. Herein, we describe the synthesis and characterizations of a new lanthanide framework, La(C40H40N4O8)(NH2(CH2)2)NO3 or MMCF-3, which retains a vacancy in the macrocycle unit encourages the utilization of the framework as a cation receptor and precursor for heterometallic frameworks. The inclusion of azamacrocycles into MOF materials combine the characteristic high thermodynamic stability, basicity, and strong metal complexation of the macrocycles with the high porosity, surface area, and tunability of the frameworks. Full realization of the potential of Azamacrocyclic-based MOFs requires the preparation of new entrants to this class of materials that espouse various topological structures while incorporating diverse azamacrocycles. It has been shown that the hierarchical porosity associated with macrocyclic based frameworks can be obtained using this class of ligands.71,99 The development of more frameworks exhibiting this characteristic is needed to fully investigate the potential applications of MOFs retaining the vacant cavities of the azamacrocycles. Effectuation of hierarchical porosity of azamacrocyclic frameworks will broaden sensing applications, e.g. azamacrocycles have performed as receptors of anions, cations, amino acids and other analyte molecules, and provide an ideal slot to integrate open metal site into MOFs.
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Mu, Bin. "Synthesis and gas adsorption study of porous metal-organic framework materials." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41097.
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Metal-organic frameworks (MOFs) or porous coordination polymers (PCPs) have become the focus of intense study over the past decade due to their potential for advancing a variety of applications including air purification, gas storage, adsorption separations, catalysis, gas sensing, drug delivery, and so on. These materials have some distinct advantages over traditional porous materials such as the well-defined structures, uniform pore sizes, chemically functionalized sorption sites, and potential for post-synthetic modification, etc. Thus, synthesis and adsorption studies of porous MOFs have increased substantially in recent years. Among various prospective applications, air purification is one of the most immediate concerns, which has urgent requirements to improve current nuclear, biological, and chemical (NBC) filters involving commercial and military purposes. Thus, the major goal of this funded project is to search, synthesize, and test these novel hybrid porous materials for adsorptive removal of toxic industrial chemicals (TICs) and chemical warfare agents (CWAs), and to install the benchmark for new-generation NBC filters. The objective of this study is three-fold: (i) Advance our understanding of coordination chemistry by synthesizing novel MOFs and characterizing these porous coordination polymers; (ii) Evaluate porous MOF materials for gas-adsorption applications including CO2 capture, CH4 storage, other light gas adsorption and separations, and examine the chemical and physical properties of these solid adsorbents including thermal stability and heat capacity of MOFs; (iii) Evaluate porous MOF materials for next-generation NBC filter media by adsorption breakthrough measurements of TICs on MOFs, and advance our understanding about structure-property relationships of these novel adsorbents.
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Ghashat, Hesham. "The governance of Libyan ports : determining a framework for successful devolution." Thesis, Edinburgh Napier University, 2012. http://researchrepository.napier.ac.uk/Output/5729.
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Following a period of isolation, and particularly since the lifting of sanctions imposed by the United Nations at the beginning of the 1990s in 2003, Libya's economy has witnessed a remarkable growth with a corresponding increase in external trade. The country's economic policy has changed and become more liberalised; involving a move towards a market economy, an increase in the participation of the private sector in all economic activities, and diversification of the sources of national income. At the port sector level Libya aims to rehabilitate and modernise the container port sector, in order to cope with the technological development that has occurred in the global shipping and port industry. The future of the sector will also involve moving beyond serving the local trade; there is a desire to convert one or more of country's ports into a hub in the Mediterranean region, and as a gateway serving the trade oflandlocked countries. Many researchers have suggested that to handle changes in the operational environments at the ports the structure of the port should be an organic one in order to secure port responsiveness. Organic structure can be achieved via implementation of a devolution policy, and over the past two decades, devolution of port governance has proved to be one way of enhancing the efficiency of ports and of handling port authorities/governments strategy shifts. Furthermore; thus far changes in governance structure, via the implementation of devolution policy, have assisted in resolving port problems, which include physical, management and administration. This research contributes significantly to the literature in the field of ports' studies; offering the policy makers of Libya with a guide for the best way to govern the port sector in Libya and outlining the steps that need to be followed to achieve this. To achieve this, the thesis reviews the policy of port devolution, and the current situation within Libya's port industry in detail; discussing the challenges' facing the Libyan port sector (container and general cargo ports). Empirically, the necessity for the devolution of Libya's ports is examined with a matching framework analysis and this is further demonstrated via a stakeholders' attitudinal survey, including suggestions for the best future governance structure and the expected impact of adopting a devolution policy. The findings are validated using a Delphi survey; the technique was utilised to deduce the critical determinants for the successful implementation of a port devolution policy in Libya. The findings reveal that in order to help the sector to survive in the existing competitive environment, the technical performance of Libya's ports needs to be improved. A fundamental change to the governance structure of the sector is perceived as a top priority for enhancing its performance; the results confirm that the allocation of responsibility for port functions does not fall neatly into the categories proposed in the widely-accepted port privatisation matrix, and is instead subject to different factors, e.g. the country's financial capabilities. A further contribution is that stakeholder interests were used as a basis for measuring the performance of the new governance structure. The analysis indicates that changes in port governance structure are widely expected to have a positive impact, leading to benefits for the majority of port stakeholders. However, the success of the devolution policy was found to be determined by factors beyond the selection of an appropriate governance structure and stakeholder satisfaction; some of the success factors identified relate to the institutional environment of the port sector. By combining the findings of the primary surveys with the literature, a systematic integrated vision for the success of port devolution in Libya is proposed.
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Inge, Andrew Kentaro. "Open-Framework Germanates : Synthesis, Structure, and Characterization." Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-75732.
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Novel open-framework germanates and open low-dimensional structures were synthesized and characterized. Their crystal structures were solved by single crystal X-ray diffraction or X-ray powder diffraction combined with other techniques. Although related open-framework materials, such as zeolites, are of interest for the ability to selectively accommodate guest species in their rings, pores and channels, germanates are primarily of interest for their unique structural properties. Compared to aluminosilicate-based zeolites, germanium oxides readily form frameworks with extra-large rings and low framework density. The formation of elegant germanate architectures is attributed to the unique Ge-O bond geometries compared to Si-O, and the tendency to form large clusters. This thesis is to serve as an introduction to germanate synthesis, structures and characterization. Structures are categorized in accordance to their building units; the Ge7X19 (Ge7), Ge9X25-26 (Ge9) and Ge10X28 (Ge10) (X = O, OH, or F) clusters. Structure determination techniques as well as the characterization techniques used to examine the properties of the materials are presented. While most of the discussed techniques have routinely been used to study crystalline open-frameworks, we introduce the use of infrared spectroscopy for the identification of cluster types, valuable for structure determination by X-ray powder diffraction. Structures and properties of the novel materials ASU-21, SU-62, SU-63, SU-64, SU-65, SU-66, SU-71, SU-72, SU-73, SU-74, SU-75 and SU-JU-14 are described and put into context with previously known structures. The novel structures are all built of the Ge7, Ge9 or Ge10 clusters, and vary from a framework with novel topology to the first open zero-dimensional germanate cavities built of such clusters.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Submitted. Paper 3: Manuscript. Paper 4: Submitted. Paper 6: Submitted. Paper 7: Manuscript. Paper 8. Manuscript. Paper 10: Unpublished book chapter.
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Crowe, Jonathan William. "Design and Synthesis of Dehydrobenzoannulene Based Covalent Organic Frameworks." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492098595103764.
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Karra, Jagadeswarareddy. "Development of porous metal-organic frameworks for gas adsorption applications." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45751.
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Metal-organic frameworks are a new class of porous materials that have potential applications in gas storage, separations, catalysis, sensors, non-linear optics, displays and electroluminescent devices. They are synthesized in a "building-block" approach by self-assembly of metal or metal-oxide vertices interconnected by rigid linker molecules. The highly ordered nature of MOF materials and the ability to tailor the framework's chemical functionality by modifying the organic ligands give the materials great potential for high efficiency adsorbents. In particular, MOFs that selectively adsorb CO₂ over N₂, and CH₄ are very important because they have the potential to reduce carbon emissions from coal-fired power plants and substantially diminish the cost of natural gas production. Despite their importance, MOFs that show high selective gas adsorption behavior are not so common.
Development of MOFs for gas adsorption applications has been hindered by the lack of fundamental understanding of the interactions between the host-guest systems. Knowledge of how adsorbates bind to the material, and if so where and through which interaction, as well as how different species in adsorbed mixture compete and interact with the adsorption sites is a prerequisite for considering MOFs for adsorptive gas separation applications. In this work, we seek to understand the role of structural features (such as pore sizes, open metal site, functionalized ligands, pore volume, electrostatics) on the adsorptive separation of CO₂, CO and N₂ in prototype MOFs with the help of molecular modeling studies (GCMC simulations). Our simulation results suggest that the suitable MOFs for CO₂ adsorption and separation should have small size, open metal site, or large pore volume with functionalized groups.
Some of the experimental challenges in the MOF based adsorbents for CO₂ capture include designing MOFs with smaller pores with/without open metal sites. Constructing such type of porous MOFs can lead to greater CO₂ capacities and adsorption selectivities over mixtures of CH₄ or N₂. Therefore, in the second project, we focused on design and development of small pore MOFs with/without open metal sites for adsorptive separation of carbon dioxide from binary mixtures of methane and nitrogen. We have synthesized and characterized several new MOFs (single ligand and mixed ligand MOFs) using different characterization techniques like single-crystal X-ray diffraction, powder X-ray diffraction, TGA, BET, gravimetric adsorption and examined their applicability in CO₂/N₂ and CO₂/CH₄ mixture separations. Our findings from this study suggest that further, rational development of new MOF compounds for CO₂ capture applications should focus on enriching open metal sites, increasing the pore volume, and minimizing the size of large pores.
Flue gas streams and natural gas streams containing CO₂ are often saturated by water and its presence greatly reduces the CO₂ adsorption capacities and selectivities. So, in the third project, we investigated the structural stability of the developed MOFs by measuring water vapor adsorption isotherms on them at different humid conditions to understand which type of coordination environment in MOFs can resist humid environments. The results of this study suggest that MOFs connected through nitrogen-bearing ligands show greater water stability than materials constructed solely through carboxylic acid groups.
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Streb, Carsten. "Functional polyoxometalate assemblies : from host-guest complexes to porous frameworks." Thesis, University of Glasgow, 2008. http://theses.gla.ac.uk/120/.
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The host-guest chemistry of two sets of isopolyoxometalate clusters is investigated. In particular the binding modes of cationic alkali and alkali earth metals through coordinative interactions with the cluster anions {Mo36} and {W36} were compared and contrasted. It was shown that the ionic radii of the cations are crucial in the isolation of discrete molecules or infinite 3D frameworks. Crystal engineering allowed the introduction of organic amine guest molecules by the formation of a set of intermolecular interactions between the cluster anions and the amine cations. In addition it was shown that by engaging the ammonium guest molecules in additional supramolecular interactions, the framework assembly in the solid state could be directed. Further investigations focused on the assembly of supramolecular polyoxometalate-based framework materials where organic ammonium cations were used as hydrogen-bond donors. The structural effects of three amines were compared and contrasted and it was established that the use of rigid planar molecules resulted in the formation of 2D networks whereas the use of flexible amines gave supramolecular 1D chains. Based on these results the synthesis of a functional framework was achieved; a three-component approach allowed the formation of a chiral, porous framework which shows structural stability and reversible solvent sorption properties. In a different approach, the cross-linking of polyoxometalates using transition metal linkers in organic solvents was studied. It was shown that silver(I) cations are highly versatile linking units and allow the linking of {V10} cluster anions into 1D zigzag chains and 2D planar networks. The silver units assemble into supramolecular, trinuclear complexes which are supported by bridging organic ligands. Careful choice of the reaction conditions allowed the formation of a 3D framework based on {W12} units. The tungstate clusters are cross-linked by dinuclear {Ag2} linkers which are held together by argentophilic silver-silver interactions and result in the formation of a porous framework. The material features reversible sorption capabilities and can be used to sequester small molecules as well as transition metal cations from organic solvents.
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Ndamyabera, Christophe Adrien. "Porous metal-organic frameworks for sorption of volatile organic compounds." Doctoral thesis, Faculty of Science, 2021. http://hdl.handle.net/11427/33877.
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Metal-organic frameworks (MOFs) present potential for various applications such as gas sorption, gas storage, sensing, drug delivery, and catalysis. This attracts researchers to design and synthesize MOFs that can respond to a specific application. In this thesis, mixed ligands 34pba and 44pba ligands (34pba = 3-(4-pyridyl)benzoate, and 44pba = 4-(4-pyridyl)benzoate) and Co2+ metal salts were used to synthesize porous MOFs {[Co(34pba)(44pba)]·DMF}n (1) and {[Co(34pba)(44pba)]·(C3H6O)}n (2), with DMF = N,N'-dimethylformamide and C3H6O = acetone through solvothermal reaction. These two relate to each other through hinge-like expansion or contraction of the guest-accessible void. The use of Zn2+ as a metal ion led to an isostructural MOFs [Zn(34pba)(44pba)]·DMF}n (3) of 1. Using 34pba as a single ligand and Cu2+ as the metal ion led to the formation of a 2D [(Cu(34pba)2]·DMF) (4) while a little variation of solvent mixture resulted in a 3D {[CuCl2(34pba)2]∙solvent}n (7) structures. The functionalized ligands 44paba and 34paba (34paba = 3-(pyridyn-4-ylmethyl)aminobenzoate, 44paba = 4-(pyridyn-4- ylmethyl)aminobenzoate) were used with Cu2+ centre to prepare [Cu(44paba)·(H2O)·(DMF)]n (5) and {[Cu3(34paba)5(H2O)2]·(DMF)2}n (6), both of which are 1D structures. The activated MOFs 1d and 3d from (1 and 2) were used for the adsorption of volatile organic compounds (VOCs) and gases. In all tested guest molecules, there was higher sorption capacity in 1d which could be attributed to some gate opening process occurring which does not occur in 3d. Some effects responding to the sorption such as the change of colour in 1d were characterized. This colour change may be associated with the d-d, metal to ligand charge transfer, or π to π* transitions in coordination complex. Crystal structures and their stability, sorption properties and selectivity were characterized by single crystal X-ray diffraction, thermogravimetric analysis, differential scanning, hot stage microscopy, powder X-ray diffraction, infrared spectroscopy, and proton viii nuclear magnetic resonance (1H NMR) analysis. This thesis also reports the effect of methanol on discrete complexes of cis-dichloro-bis(ethylenediamine)cobalt(III) chloride (Coen) that led to the formation of a new crystal structure upon the removal of the water of hydration. The lattice energies calculated prove that Coen is more stable to allow a quick reversible sorption.
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Nevin, Adam C. "Refining pore size, functionality and stability in porous hybrid frameworks." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/40506/.
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This thesis describes the utilisation of a new, facile route for rapid ligand synthesis for the design, synthesis and characterisation of metal-organic frameworks (MOFs), and the subsequent refinement of ligand synthesis to discover a 2-step green alternative synthetic route to an analogous ligand for use in the same. From these ligands, two series of MOFs are detailed; a Cu(II) series with simulated isotherms showing promising CH4 and CO2 high pressure uptake, and two Zr(IV) MOFs with enhanced stability and their measured high pressure isotherms. Chapter 1 introduces the need for highly functional materials to answer the needs of current energy production crises; with the production of CO2 from fossil fuels predicted to continue dangerously damaging the environment for decades to come, while the fossil fuel energy sources themselves run out, alternatives are clearly needed to continue powering society. MOFs are introduced as potential materials which can fulfil both of these needs. Chapter 2 describes the synthesis of the H4LX series, which utilise the Suzuki-Miyaura cross-coupling reaction to generate a large quantity of a versatile ligand pre-cursor (3,5-di(p-carbethoxy)benzene boronic acid), which is then used to generate a large number of ligands via a further Suzuki-Miyaura cross-coupling reaction with a dihalogenated core. A green synthetic route to an analogous ligand to the first in the series (H4L1P, which differs from H4L1 by the replacement of two phenyl rings with pyridyls) is then described, which reduces the synthetic steps by 66% (2 steps instead of 6), and the cost by 95% (£0.51/g instead of £11.68/g). Chapter 3 describes the design, synthesis, and characterisation of a series of Cu(II) metal-organic frameworks (MFM-191 to 198), and their respective simulated isotherms, which enable rapid identification of promising frameworks for materials which theoretically approach and even exceed the American Department of Energy’s (DoE’s) target value for CH4 working capacity, and also potentially provide an alternative to current proposals for CO2 storage and shipping. The discussion on these frameworks is split into two studies: Exploration of the effects of interpenetration and classes thereof on low and high pressure gas sorption (MFM-191,192 and 193), and analysis of attempts to fine tune the high pressure uptake of a series of non-interpenetrated isoreticular structures via extension and functionalisation of the central core of the ligand (MFM-193 to 198). The first group of frameworks demonstrates how interpenetration aids low pressure uptake, but hinders maximum high pressure uptake. MFM-191 (which exhibits 2-fold interpenetration, class IIa) displays an uptake of CH4 of 1.97 wt% at 1 bar and 21.40 wt% and 80 bar, 298 K and an uptake of CO2 of 2.88 mmol/g at 1 bar, and 16.69 mmol/g at 30 bar, 298 K; while MFM-193 (a non-interpenetrated MOF with the same topology) demonstrates a greater difference between uptakes, with uptakes for CH4 of 0.85 wt% at 1 bar and 47.06 wt% for 80 bar, 298 K, and uptakes for CO2 of 0.65 mmol/g at 1 bar and 40.82 mmol/g at 30 bar, 298 K. This larger difference is due to the decreased host-guest interactions at low loadings, and works in favour of a better working capacity for CH4 for the non-interpenetrated framework. Alteration of the class of interpenetration (from class IIa to class Ia) results in overall uptake behaviour which lies between the two, displaying an uptake for MFM-192 of CH4 of 2.11 at 1 bar, and 31.36 wt% at 80 bar, 298 K and an uptake of 2.89 2.89 mmol/g at 1 bar and 24.07 mmol/g at 30 bar for CO2 at 298 K. The non-interpenetrated series of MOFs (MFM-193 to 198), shows how upon functionalisation of the central core of ligand H4L1, the gas sorption properties are increases in accordance to the aromaticity of the ligand, with an increase in maximum volumetric uptake (at 80 bar, 298 K) of CH4 from 233.29 to 251.89 cm3/cm3 from MFM-193 (with H4L1, a ligand with a phenyl ring as the central core) to MFM-195 (synthesised from H4LAN, a ligand with an anthracene moiety as its central core). Surprisingly, the amine-functionalised MOF (MFM-196) displays the lowest uptake of both CH4 and CO2 at high pressure compared to the other functionalised MOFs (MFM-194 and MFM-195) Extension of the ligand core from one phenyl ring to biphenyl and pyrene based ligands affords MFM-197 and MFM-198, which in turn display the highest theoretical gravimetric CH4 working capacities 5-80 bar (48.51 wt% and 44.15 wt% at 298 K, respectively). Furthermore, working capacities calculated from the 273 K simulated isotherms for MFM-198 (the pyrene functionalised framework) show that this MOF is capable of exceeding the DoE target for gravimetric working capacity of 50 wt% (and nearing the volumetric target of 264 cm3 cm-3), by delivering 52.3 wt% and 256.9 cm3 cm-3 between 5-80 bar. However, upon attempts to activate these Cu(II) frameworks, none were stable enough to obtain a permanent porosity, even from ‘soft’ activation methods such as supercritical CO2; therefore, new frameworks were sought which would be designed to have enhanced stability. Chapter 4 describes the synthesis of two Zr(IV) MOFs, synthesised from H4L1 and H4L1P (MFM-421 and MFM-422) designed to display enhanced stability over the Cu(II) MOF series, and allow acquisition of experimentally gathered high pressure data. This is particularly interesting for the MOF synthesised from H4L1P, as the green, cost-effective synthesis conditions of the ligand are potentially valuable for industrial applications. Both MOFs display an increase in stability over the Cu(II) series, with a measureable BET of 3,300 m2/g for MFM-421 and 2,500 m2/g for MFM-422. The high pressure CH4 and CO2 capacities of both frameworks were measured, and, while they were lower than the simulated Cu(II) series, they were highly competitive compared to published MOFs. MFM-421 is shown to have the fourth highest CH4 gravimetric working capacity at 298 K (compared to a list of the highest experimentally recorded MOFs for methane working capacity), and MFM-422 the sixth, measuring values of 25.7 wt% and 22.8 wt%, compared to the three highest of 31.0 wt%, 35.0 wt% and 42.3 wt% for MOF-177, MOF-205 and Al-soc-MOF-1, respectively. Importantly, compared to HKUST-1 (the only framework amongst this list that is cheaper than H4L1P to buy/synthesise), both of these frameworks exhibit higher gravimetric working capacities (which for HKUST-1 is 16.3 wt% at 298 K). The analysis of CO2 high pressure isotherms for potential in storage and shipping shows that these MOFs exhibit an increase in storage capacity at 298 K, 30 bar over capacity of a tank at the same conditions of over 500% for MFM-421 (7,708 mol/m3 compared to 1,458 mol/m3) and over 650% for MFM-422 (9,605 mol/m3). While the highest of these values still stands at only 43% of the value of a tank at 26.5 bar and 263 K, the ability to store this much CO2 at ambient temperatures allows more flexibility in route and less energy intensive storage conditions. Chapter 5 summarises the CH4 and CO2 storage properties of these structures and draws overall conclusions from the work.
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Lee, Lisa S. "Design of porous solids from 2-D and 3-D coordination frameworks utilizing imidazolylbenzoic acids and esters." Digital WPI, 2008. https://digitalcommons.wpi.edu/etd-theses/1017.
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"The investigation through design and synthesis of metal-organic frameworks was conducted in an effort to create new types of porous crystalline solids. The supramolecular chemistry and crystal structures of six novel frameworks (1-Cd, 2Cd, 1-Cu, 2a-Cu, 2b-Cu, 3-Cu) are reported. We are targeting porous solids composed of the transition metals Cu2+ and Cd2+ with three related families of organic molecules: Ethyl 4-(1H-imidazol-1-yl)benzoate, 4-(1H-benzo[d]imidazol-1-yl)benzoic acid, and Ethyl 4-(2-methyl-1H-imidazol-1-yl)benzoate. These molecular building blocks self assemble via metal coordination into coordination polymers that form a variety of 1-D, 2-D, and 3-D architectures. The networks are comprised of M•••O and M•••N bonds that coordinate into different geometrical arrangements dependent on steric hindrance and the metal ions that are used. The frameworks synthesized display porous behavior using weight measurements that are also seen to be reversible in some cases using atmospheric reuptake of guest molecules from growth solution. The uptake of rhodamine b was examined for the framework 3-Cu."
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Lively, Jason M. "In Situ Ion Exchange in a Micro-porous Transition Metal Silicate Framework." TopSCHOLAR®, 2016. http://digitalcommons.wku.edu/theses/1730.
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Ion selectivity of minerals has traditionally been utilized in industry as a catalyst, metal separation, and environmental reclamation/sequestration tool. There is an increased interest in understanding ion selectivity mechanisms of micro-porous minerals and mineral-like structures and how they can be applied in various industries: environmental and, potentially, pharmaceutical. This study seeks to understand the ion exchange mechanisms in micro-porous zirconosilicates using time-resolved Raman spectroscopy and X-ray diffraction. The thesis material was exchanged with H+, Na+, K+, and Cs+ in order to better understand structural changes as well as the influence of the H+-bonding during the exchange process. It is hypothesized that the host (H+) ion strongly influences the ion selectivity of the mineral by changing framework polyhedra and ring geometry, and the geometry of the interstitial the OH…H2O bond network to only allow cations of certain sizes through the channels. In addition, the H+ may repel cations with high charge densities from entering the extra-framework sites in the crystal structure by protonating the channel pathways.
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Yigit, Mehmet Veysel. "Design of open hydrogen-bonded frameworks using bis(imidazolium 2,4,6-pyridinetricarboxylate)metal complexes as secondary building units." Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0514103-110657.
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Annamalai, Perushini. "Electrospinning of porous composite materials for hydrogen storage application." University of the Western Cape, 2016. http://hdl.handle.net/11394/5654.
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>Magister Scientiae - MScDue to the rapid depletion of fossil fuel reserves and the production of environmentally harmful by-products such as carbon dioxide, there is an urgent need for alternate sustainable clean energy. One of the leading candidates in this endeavour is hydrogen, which can be used as an energy carrier since it has a high energy density, zero emissions and is produced from non-depletable resources such as water. The major challenge hindering a hydrogen economy is the lack of safe and effective storage technologies for mobile applications. A prospective solution to this problem lies in the use of porous powdered materials, which adsorb the hydrogen gas. However, the integration of these powdered materials into a storage tank system, results in the pipelines being contaminated during filling cycles. This necessitates the shaping of the porous powdered materials. Among the many shaping techniques available, the electrospinning technique has been proposed as a promising technology since it is a versatile process that is easily scaled-up making it attractive for the applications of the study. Furthermore, the electrospinning process enables the synthesis of nano-sized fibres with attractive hydrogen sorption characteristics. In this regard, the current study employs the electrospinning technique to synthesise electrospun composite fibres for mobile hydrogen storage applications. After electrospinning three polymers, polyacrylonitrile (PAN) was selected as the most suitable polymer because it yielded bead-free electrospun fibres. However, the diameter of the PAN fibres was large/thick which prompted further optimisation of the electrospinning parameters. The optimised electrospinning conditions that yield unbeaded fibres within the desired diameter range (of 300-500 nm) were a PAN concentration of 10 wt%, a flow rate of 0.4 mL/h, a distance of 10 cm between the needle tip and collector plate, and an applied voltage of 8 kV. The study then progressed to the synthesis and characterisation of the pristine porous powdered materials which adsorb hydrogen gas. The porous powdered materials investigated were commercial zeolite 13X, its synthesised templated carbon derivative (ZTC) and Zr (UiO-66) and Cr (MIL-101) based metal-organic frameworks (MOFs). ZTC was synthesised via liquid impregnation coupled with chemical vapour deposition (CVD), and the MOFs were synthesised by the modulated solvothermal method. Analysis of the ZTCs morphology and phase crystallinity show that the carbon templated process using zeolites was successful, however, ZTC was amorphous compared to crystalline zeolite template. The BET surface area was assessed with the aid of nitrogen sorption isotherms for both zeolite 13X and ZTC, and values of 730 and 2717 m²/g, respectively were obtained. The hydrogen adsorption capacity for zeolite 13X was 1.6 wt% and increased to 2.4 wt% in the ZTC material at 77 K and 1 bar. The successful synthesis of well defined, crystalline MOFs was evident from X-ray diffraction and morphological analysis. The BET surface area and hydrogen adsorption for Zr MOF were 1186 m²/g and 1.5 wt%, respectively at 77 K and 1 bar. Cr MOF had a BET surface area of 2618 m²/g and hydrogen adsorption capacity of 1.9 wt% at 77 K and 1 bar. The main focus of the study was to synthesise electrospun composite fibres that can adsorb hydrogen gas and thus provide significant insight in this field of research. As such it examined composite fibres that incorporates porous powdered materials such as zeolite 13X, ZTCs, UiO-66 (Zr) MOF and MIL-101 (Cr) MOF and investigated their ability to adsorb hydrogen gas, which have not been reported previously. The synthesis of composite fibres was achieved by incorporating the porous powdered materials into the PAN resulting in a polymeric blend that was then electrospun. Morphological analysis illustrated that the porous powdered materials were successfully supported by or incorporated within the PAN fibres, forming composite fibres. The BET surface area of the 40 wt% zeolite-PAN and 12.5 wt% ZTC-PAN composite fibres were 440 and 1787 m²/g respectively. Zr MOF and Cr MOF composite fibres had a BET surface area of 815 and 1134 m²/g, respectively. The BET surface area had reduced by 40, 34, 31 and 57% for zeolite 13X, ZTC, Zr MOF and Cr MOF, respectively after these porous powdered materials were incorporated into PAN. The hydrogen adoption capacity for 40 wt% zeolite-PAN, 12.5 wt% ZTC-PAN, 20 wt% Zr MOFPAN and 20 wt% Cr MOF-PAN composite fibres was 0.8, 1.8, 0.9 and 1.1 wt%, respectively. This decrease was attributed to the limited amount of porous powdered materials that could be incorporated into the fibres since only 40 wt% of zeolite 13X, 12.5 wt% of ZTC and 20 wt% of the MOFs were loaded into their respective composite fibres. This was due to the fact that incorporation of greater amounts of porous powdered materials resulted in a viscous polymeric blend that was unable to be electrospun. It is evident from the study that electrospinning is a versatile process that is able to produce composite fibres with promising properties that can potentially advance the research in this field thus providing a practical solution to the problem of integrating loose powdered materials into an on-board hydrogen storage system.
CSIR Young Researchers Establishment Fund (YREF)
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Liu, Leifeng. "Inorganic and Metal-Organic Framework Materials : Synthesis and structure characterization." Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-102816.
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Inorganic and metal-organic framework materials possessing accessible and permanent pores are receiving tremendous attention. Among them, zeolites are the most famous class due to their wide applications on petrochemistry and gas separation. Besides zeolites, the other oxide framework materials are also intensively investigated because of their diverse structures and compositions. Metal-organic frameworks are built from metal clusters and organic linkers. By rational designing the reagent, the network with desired topology and functionality can be synthesized. For all of the framework materials mentioned above, to explore novel framework structures is important for improving properties and discovering new applications. This thesis includes the synthesis of zeolites and structure characterization for various types of inorganic framework materials. The zeolite synthesis conditions was exploited. With the optimized condition, the zeolite ITQ-33 was synthesized as single crystals. From the single crystal X-ray diffraction data, the disorder in the structure is discovered and explained. Following the topic of disorder and twinning, we proposed a novel method of solving structure of pseudo-merohedric twinning crystal by using an example of a metal-organic complex crystal. Then we also showed methods for solving structures of high complexity and nano-crystal by using mainly powder X-ray diffraction and transmission electron microscopy. Four examples were shown in chapter 4 including open-framework germanates and metal-organic frameworks.At the time of the doctoral defence the following paper was unpublished and a status as follows: Paper 4: Manuscript
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Inubushi, Yasutaka. "Studies on Porous Coordination Polymers for Methane Purification." 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225308.
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Liang, Weibin. "Carbon Dioxide Adsorption and Catalytic Conversion in Porous Coordination Polymers." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14541.
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This thesis reports an investigation into carbon dioxide capture and catalysis in several target metal-organic frameworks (MOFs) and porous organic polymers (POPs). In chapter 2, a series of Zr-MOFs were synthesised for potential applications in carbon capture and storage. In the first instance, a novel Zr-based MOF was constructed exclusively from the monocarboxylate ligand formate. Despite the low surface area, the new material exhibited a high affinity for CO2 over nitrogen at room temperature. In addition, the water-stable Zr–tricarboxylate series of frameworks, exhibited tunable porosity by virtue of systematic modulation of the chain length of the monocarboxylate ligand. Last but not least, defect concentrations and their compensating groups have been systematically tuned within UiO-66 frameworks by using modified microwave-assisted solvothermal methods. Both of these factors have a pronounce effect on CO2 and H2O adsorption at low and high pressure. Chapter 3 focuses on the development of a rapid and efficient microwave-assisted solvothermal method for a series of zirconium oxide based MOFs known as MIL-140s. Combined experimental and computational studies have revealed the interplay between the framework pore size and functionality on the CO2 adsorption performance of MIL-140 frameworks. The potential for CO2 photocatalysis in POPs was also explored in chapter 4. A POP with free 2,2’-bipyridyl sites was prepared via Sonogashira-Hagihara coupling and catalytically active moieties ([(α-diimine)Re(CO)3Cl]) were introduced using a post-synthesis metalation method. Thereafter, the Re-containing porous organic polymer was tested for the photocatalytic reduction of CO2. After an induction period, Re-POP produced CO at a stable rate, unless soluble [(bpy)Re(CO)3Cl] (bpy = 2,2´-bipyridine) was added. This provides some of most convincing evidence to date that [(α-diimine)Re(CO)3Cl] catalysts for photocatalytic CO2 reduction decompose via a bimetallic pathway.
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Pyles, David Andrew. "Design and Application of Novel Benzobisoxazole and Benzobisthiazole Linked Porous Polymers." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu155428770646841.
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Akiyama, George. "Studies on Synthesis and Application of Water Durable Porous Coordination Polymers." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/198948.
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Collins, Sean. "Parameterization, Pores, and Processes: Simulation and Optimization of Materials for Gas Separations and Storage." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39382.
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This thesis explores the use of computational chemistry to aid in the design of metal-organic frameworks (MOFs) and other materials. A focus is placed on finding exceptional materials to be used for removing CO2 from fossil fuel burning power plants, with other avenues like vehicular methane storage and landfill gas separation being explored as well. These applications are under the umbrella of carbon capture and storage (CCS) which aims to reduce carbon emissions through selective sequestration. We utilize high-throughput screenings, as well as machine learning assisted discovery, to identify ideal candidate materials using a holistic approach instead of relying on conventional gas adsorption properties.
The development of ideal materials for CCS requires all aspects of a material to be considered, which can be time-consuming. A large portion of this work has been with high-throughput, or machine learning assisted discovery of ideal candidates for CCS applications. The chapters of this thesis are connected by the goal of finding ideal materials for CCS. They are primarily arranged in increasing complexity of how this research can be done, from using high-throughput screenings with more simple metrics, up to multi-scale machine learning optimization of pressure swing adsorption systems. The work is not presented chronologically, but in a way to tell the best story.
Work was done by first applying high-throughput computational screening on a set of experimentally realized MOFs for vehicular methane storage, post-combustion carbon capture, and landfill gas separation. Whenever possible, physically motivated figures of merits were used to give a better ranking and consideration of the materials. From this work, we were able to determine what the realistic limits might be for current MOFs. The work was continued by looking at carbon-based materials (primarily carbon nanoscrolls) for post-combustion carbon capture and vehicular methane storage. The carbon-based materials were found to outperform MOFs; however, further studies are needed to verify the results.
Next, we looked at ways to improve the high-throughput screening methodology. One problem area was in the charge calculation, which could lead to unrealistic gas adsorption results. Using the split-charge equilibration method, we developed a robust way to calculate the partial atomic charges that were more accurate than its quick calculation counterparts. This led to gas adsorption properties which more closely mimicked the results determined from time-consuming quantum mechanically derived charges.
Simplistic process optimization was then applied to nearly ~3500 experimental structures. To the best of our knowledge, this is the first time that any process optimization has been applied to more than 10s of materials for a study. The process optimization was done by evaluating the desorption at various pressures and choosing the value which gave the lowest energetic cost. It was found that a material synthesized by our collaborators, IISERP-MOF2, was the single best experimentally realized material for post-combustion carbon capture. What made this an interesting result is that by conventional metrics IISERP-MOF2 does not appear to be outstanding. Next, functionalized versions of MOFs were tested in a high-throughput manner, and some of those structures were found to outperform IISERP-MOF2.
Although high-throughput computational screenings can be used to determine high-performance materials, it would be impossible to test all functionalized versions of some MOFs, let alone all MOFs. Functionalized MOFs are noteworthy because MOFs are highly tuneable through functionalization and can be made into ideal materials for a given application. We developed a genetic algorithm which, given a base structure and a target parameter, would be able to find the ideal functionalization to optimize the parameter while testing only a small fraction of all structures. In some cases, the CO2 adsorption was found to more than quadruple when functionalized.
A better understanding of how materials perform in a PSA system was achieved by performing multi-scale optimizations. Experimentally realized MOFs were tested using atomistic simulations to derive gas adsorption properties. After passing through a few sensible filters, they were then screened using macro-scale pressure swing adsorption simulators, which model how gas separation may occur at a power plant. Using another genetic algorithm, the conditions that the pressure swing adsorption system runs at was optimized for over 200 materials. To the best of our knowledge, this is the highest amount of materials that have had been optimized for process conditions. IISERP-MOF2 was found to perform the best based on many relevant metrics, such as the energetic cost and how much CO2 was captured. It was also found that conventional metrics were unable to be used to predict a material’s pressure swing adsorption performance.
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Mochizuki, Shuto. "Controlled radical polymerization in designed porous materials." Kyoto University, 2019. http://hdl.handle.net/2433/242535.
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Tanaset, Anont. "Regio- and size-selective catalysis : porous aromatic frameworks and C3-symmetric receptors." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107571.
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Thesis: S.M., Massachusetts Institute of Technology, Department of Chemistry, 2016.Cataloged from PDF version of thesis.
Includes bibliographical references.
Porous aromatic frameworks (PAFs) have recently emerged as a new class of materials with impressive stability and high surface area, which led to their applications in gas storage and small molecule recognition. Herein, the synthesis and functionalization of PAFs were described, and their potential use as selective oligomerization for fuel upgrading was investigated. However, functionalized PAFs showed undesired reactivity possibly due to low rate of substrate and product diffusion in and out of the framework. On the other hand, a novel C3-symmetric hydrogen bonding receptor was synthesized and investigated for its use as size- and regioselective catalyst. It was demonstrated that the receptor was able to distinguish substrates with different functional groups in binding experiments, and was able to improve SN2 reaction yield although with some significant limitations.
by Anont Tanaset.
S.M.
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Carson, Fabian. "Development of Metal–Organic Frameworks for Catalysis : Designing Functional and Porous Crystals." Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-115819.
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Metal–organic frameworks, or MOFs, have emerged as a new class of porous materials made by linking metal and organic units. The easy preparation, structural and functional tunability, ultrahigh porosity, and enormous surface areas of MOFs have led to them becoming one of the fastest growing fields in chemistry. MOFs have potential applications in numerous areas such as clean energy, adsorption and separation processes, biomedicine, and sensing. One of the most promising areas of research with MOFs is heterogeneous catalysis. This thesis describes the design and synthesis of new, carboxylate-based MOFs for use as catalysts. These materials have been characterized using diffraction, spectroscopy, adsorption, and imaging techniques. The thesis has focused on preparing highly-stable MOFs for catalysis, using post-synthetic methods to modify the properties of these crystals, and applying a combination of characterization techniques to probe these complex materials. In the first part of this thesis, several new vanadium MOFs have been presented. The synthesis of MIL-88B(V), MIL-101(V), and MIL-47 were studied using ex situ techniques to gain insight into the synthesis–structure relationships. The properties of these materials have also been studied. In the second part, the use of MOFs as supports for metallic nanoparticles has been investigated. These materials, Pd@MIL-101–NH2(Cr) and Pd@MIL-88B–NH2(Cr), were used as catalysts for Suzuki–Miyaura and oxidation reactions, respectively. The effect of the base on the catalytic activity, crystallinity, porosity, and palladium distribution of Pd@MIL-101–NH2(Cr) was studied. In the final part, the introduction of transition-metal complexes into MOFs through different synthesis routes has been described. A ruthenium complex was grafted onto an aluminium MOF, MOF-253, and an iridium metallolinker was introduced into a zirconium MOF, UiO-68–2CH3. These materials were used as catalysts for alcohol oxidation and allylic alcohol isomerization, respectively.At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 2: Manuscript. Paper 5: Manuscript.
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Stoeck, Ulrich, Irena Senkoska, Volodymyr Bon, Simon Krause, and Stefan Kaskel. "Assembly of metal–organic polyhedra into highly porous frameworks for ethene delivery." Royal Society of Chemistry, 2015. https://tud.qucosa.de/id/qucosa%3A36046.
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Two new mesoporous metal–organic frameworks (DUT-75 and DUT-76) with exceptional ethene uptake were obtained using carbazole dicarboxylate based metal–organic polyhedra as supermolecular building blocks. The compounds have a total pore volume of 1.84 and 3.25 cm³ gˉ¹ and a specific BET surface area of 4081 and 6344 m² gˉ¹, respectively, and high gas uptake at room temperature and high pressure.
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Banerjee, Tanushree. "Impact of Nickel Doping on Hydrogen Storage in Porous Metal-Organic Frameworks." VCU Scholars Compass, 2010. http://scholarscompass.vcu.edu/etd/2265.
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A supply of clean, carbon neutral and sustainable energy is the most scientific and technical challenge that humanity is facing in the 21st century. Though there is enough fossil fuels available for a few centuries, their use would increase the level of CO2 in the atmosphere. This would lead to global warming and may pose serious threats such as rising of sea level, change in hydrological cycle, etc. Hence there is a need for an alternative source of fuel that is clean and sustainable. Among the many resources considered as an alternative power source, hydrogen is considered one of the most promising candidates. To use hydrogen commercially, appropriate hydrogen storage system is required. Various options to store hydrogen for onboard use include gaseous form in high-pressure tanks, liquid form in cryogenic conditions, solid form in chemical or metal hydrides, or by physisorption of hydrogen on porous materials. One of the emerging porous materials are metal-organic frameworks (MOFs) which provide several advantages over zeolites and carbon materials because the MOFs can be designed to possess variable pore size, dimensions, and metrics. In general, MOFs adsorb hydrogen through weak interactions such as London dispersion and electrostatic potential which lead to low binding enthalpies in the range of 4 to 10 kJ/mol. As a result, cryogenic conditions are required to store sufficient amounts of hydrogen inside MOFs. Up to date several MOFs have been designed and tested for hydrogen storage at variable temperature and pressure levels. The overall results thus far suggest that the use of MOFs for hydrogen storage without chemical and electronic modifications such as doping with electropositive metals or incorporating low density elements such as boron in the MOFs backbone will not yield practical storage media. Such modifications are required to meet gravimetric and volumetric constraints. With these considerations in mind, we have selected a Cr-based MOF (MIL-101; Cr(F,OH)-(H2O)2O[(O2C)-C6H4-(CO2)]3•nH2O (n ≈ 25)) to investigate the impact of nickel inclusion inside the pores of MIL-101 on its performance in hydrogen storage. MIL-101 has a very high Langmuir surface area (5900 m2/g) and two types of mesoporous cavities (2.7 and 3.4 nm) and exhibits exceptional chemical and thermal stabilities. Without any modifications, MIL-101 can store hydrogen reversibly with adsorption enthalpy of 10 kJ/mol which is the highest ever reported among MOFs. At 298 K and 86 bar, MIL-101 can store only 0.36 wt% of hydrogen. Further improvement of hydrogen storage to 5.5 wt% at 40 bar was achieved only at low temperatures (77.3 K). As reported in the literature, hydrogen storage could be improved by doping metals such as Pt. Doping is known to improve hydrogen storage by spillover mechanism and Kubas interaction. Hence we proposed that doping MIL-101 with a relatively light metal possessing large electron density could improve hydrogen adsorption. Preferential Ni doping of the MIL-101’s large cavities which usually do not contribute to hydrogen uptake is believed to improve hydrogen uptake by increasing the potential surface in those cavities. We have used incipient wetness impregnation method to dope MIL-101 with Ni nanoparticles (NPs) and investigated their effect on hydrogen uptake at 77.3 K and 298 K, at 1 bar. In addition, the impact of metal doping on the surface area and pore size distribution of the parent MIL-101 was addressed. Metal content and NPs size was investigated by ICP and TEM, respectively. Furthermore, crystallinity of the resulting doped samples was confirmed by Powder X-ray Diffraction (PXRD) technique. The results of our studies on the successful doping with Ni NPs and their impact on hydrogen adsorption are discussed.
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Kim, Chi Won. "Synthesis of Porous Coordination Polymers for Controlled Nitric Oxide Release." 京都大学 (Kyoto University), 2016. http://hdl.handle.net/2433/204585.
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Baldwin, Luke Adam. "Synthesis of Dehydrobenzoannulene-Based Covalent Organic Frameworks." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1491561788473597.
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Iyer, Amrita. "A Framework for Air Dispersion Modeling – A Hypothetical Case of Port Operations." ScholarWorks@UNO, 2014. http://scholarworks.uno.edu/td/1813.
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One of the primary modes for pollutants to reach the human body is through their release into the atmosphere and dispersion in the nearby areas. This makes air emissions one of the important components of an environmental assessment. They are frequently of interest to the people living in the vicinity of the site. The analysis carried out in this research provides a framework for atmospheric dispersion modeling of air pollutants using AERMOD, the United States Environmental Protection Agency (US EPA) approved regulatory model, for modeling port related emissions. There are various sources of emissions from the ports, however for this study, emissions from roadways, small equipment, and marine related sources are considered. AERMOD was used to estimate ambient pollutant concentrations of selective criteria pollutants such as NOx, SO2, CO and PM10 from a hypothetical port.
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Rayder, Thomas M. "Modulation of Catalyst@MOF Host-Guest Composites in Pursuit of Synthetic Artificial Enzymes:." Thesis, Boston College, 2020. http://hdl.handle.net/2345/bc-ir:108930.
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Thesis advisor: Jeffery A. ByersThesis advisor: Chia-Kuang (Frank) Tsung
Biological systems have evolved over time to favor structures beneficial for the efficient transformation of simple feedstocks to sophisticated products. In particular, enzymes have evolved such that cooperative and geometrically controlled interactions between active sites and substrates enhance catalytic activity and selectivity. Separation of these active sites from other incompatible catalytic components allows for chemical transformation in a stepwise fashion, circumventing the inherent limitations to performing reactions in a single step. This dissertation describes the use of porous crystalline materials called metal-organic frameworks (MOFs) as hosts to mimic the component separation and precise active site control observed in nature. The first phase of these efforts explores the use of dissociative “aperture-opening” linker exchange pathways in a MOF to encapsulate transition metal complexes for carbon dioxide hydrogenation to formate. This strategy is then used to separate two incompatible complexes and perform the cascade conversion of carbon dioxide to methanol, resulting in unique and previously unobserved network autocatalytic behavior. Finally, the modularity of the MOF host is leveraged to install beneficial functionality in close proximity to the encapsulated transition metal complex, leading to activity exceeding that of any reported homogeneous system for carbon dioxide reduction. The insights gained through these studies can inform the development of composites for other reactions, allowing for access to new and unique reaction manifolds
Thesis (PhD) — Boston College, 2020
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Batisai, Eustina. "Synthesis and sorption studies of porous metal-organic hosts." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/79803.
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Thesis (PhD)--Stellenbosch University, 2013.ENGLISH ABSTRACT: The first part of this study describes the synthesis of new porous materials from basic building blocks. Five structurally related ligands namely: N,N'-bis(3-pyridylmethyl)-naphthalene diimide (L1), N,N'-bis(4-pyridylmethyl)-naphthalene diimide (L2), N,N'-bis(4-pyridylmethyl)- pyromellitic diimide (L3), N,N'-bis(3-pyridylmethyl)-pyromellitic diimide (L4) and 2-(pyridin-4- ylmethyl)-benzene tricarboxylic anhydride (L5) were synthesised. Ligands L1 and L2 were reacted with metal nitrates and carboxylates as co-ligands in a systematic manner with a view to obtaining potentially porous 3–D coordination polymers. Ten structurally diverse coordination polymers were obtained and they were characterised by single-crystal X-ray diffraction, powder X-ray diffraction and thermogravimetric analysis. Four of these compounds absorb moderate amounts of CO2 and, in addition, show sorption selectivity towards CO2 over N2. The reaction of L3 and L4 with transition metal halides yielded two 1–D chains, while the reaction of L5 with transition metal nitrates yielded seven coordination polymers of which four are 2–D and three are 1–D. Of the 2–D structures three are isostructural. The second part of this work describes a variable pressure study of a flexible metal-organic framework [Zn2(BDC)2(BPY)] (BPY = 4,4 -bipyridine and BDC = 1,4-benzene dicarboxylic acid). [Zn2(BDC)2(BPY)] is one of the few examples of a flexible metal-organic framework that undergoes phase transformations in response to gas pressure. The high pressure sorption recorded for this metal-organic framework displays two inflection steps in the pressure range 0 to 30 bar, possibly indicating two phase transformations. The gas-loaded structures for each phase transformation were determined by means of single-crystal X-ray diffraction. High-pressure differential scanning calorimetry was also carried out on the system in order to determine accurate gate-opening pressures, as well as the energies involved with each phase transformation. The results correlate with those obtained from single-crystal X-ray diffraction and high-pressure sorption. The final section reports the mechanochemical synthesis of two Werner complexes [NiCl2(4- PhPy)4] (1), [CoCl2(4-PhPy)4] (2) and their corresponding solid solution [Ni0.5Co0.5Cl2(4-PhPy)4] (3) (PhPy = phenyl pyridine). The solid solution could only be formed by mechanochemical synthesis and not by conventional solution crystallisation methods. The solid solution exhibits sorption properties that differ from those of the pure compounds.
AFRIKAANSE OPSOMMING: Die eerste deel van hierdie studie beskryf die sintese van nuwe poreuse stowwe uit basiese boublokke. Vyf struktureel verwante ligande naamlik: N,N'-bis(3-piridielmetiel)-naftaleen diimied (L1), N,N'-bis(4-piridielmetiel)-naftaleen diimied (L2), N,N'-bis(4-piridielmetiel)- piromellitien diimied (L3), N,N'-bis(3-piridielmetiel)-piromellitien diimied (L4) en 2-(piridiel-4- ielmetiel)benseen trianhidried (L5) is gesintetiseer. Ligande L1 en L2 is gereageer met metaal nitrate en karboksielsure as mede-ligande in 'n sistematiese wyse met 'n oog op die verkryging van potensieel poreuse 3–D koördinasie polimere. Tien struktureel diverse koördinasie polimere is verkry en hulle is gekarakteriseer deur enkel-kristal X-straal-diffraksie, poeier X-straal diffraksie en termo-analise (thermal analysis). Vier van hierdie verbindings het matige hoeveelhede CO2 geabsorbeer en, bykomend, wys sorpsie selektiwiteit van CO2 oor N2. Die reaksie van L3 en L4 met oorgangsmetaalhaliede het twee 1–D kettings gevorm, terwyl die reaksie van L5 met oorgangsmetaal nitrate sewe koördinasie polimere opgelewer het, waarvan vier 2–D en drie 1–D polimere is. Van die 2–D polimere het drie vergelykbare strukture. Die tweede deel van hierdie werk beskryf 'n veranderlike druk studie van 'n buigsame metaalorganiese raamwerk [Zn2(BDC)2(BPY)] (BPY = 4,4-bipiridien en BDC = 1,4-benseen dikarboksielsuur). [Zn2(BDC)2(BPY)] is een van die min voorbeelde van 'n buigsame metaalorganiese raamwerk wat fase transformasies (phase transformations) ondergaan in respons op ‘n verandering in gas druk. Die hoë-druk sorpsie aangeteken vir hierdie metaal-organiese raamwerk vertoon twee infleksie stappe in die gebestudeerde druk gebied (0 tot 30 bar), wat moontlik op twee fase transformasies dui. Die gas-gelaaide strukture vir elke fase transformasie is bepaal deur middel van enkel-kristal X-straal-diffraksie. Hoë-druk differensiële skandeer kalorimetrie (differential scanning calorimetry) is ook uitgevoer op die stelsel ten einde dié akkurate hekopenings druk, sowel as die energie betrokke by elke fase transformasie te bepaal. Die resultate stem ooreen met dié verkry vanaf enkel-kristal X-straal diffraksie en hoë-druk sorpsie. Die finale afdeling bespreek die meganochemiese sintese van twee Werner komplekse [NiCl2(4-PhPy)4] (1) en [COCl2(4-PhPy)4] (2) en hul ooreenstemmende vaste oplossing (solid solution) [Ni0.5Co0.5Cl2(4-PhPy)4] (3). Die vaste oplossing kan slegs gevorm word deur meganochemiese sintese en nie deur konvensionele oplossing kristallisasie metodes. Die vaste oplossing vertoon sorpsie eienskappe wat verskil van dié van die suiwer verbindings.
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Liu, Xin. "Syntheses, Structures and Properties of Metal-Organic Frameworks." TopSCHOLAR®, 2015. http://digitalcommons.wku.edu/theses/1499.
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Mercury is one of the most serious heavy metal pollution sources that threaten people’s health. For decades, people have developed many technologies and materials to capture mercury from flue gas of coal-fired plant. Currently, the most effective material for mercury absorption is powdered activated carbon, which shows increased efficiency when modified with halogen functional groups such as bromine. Metal-organic frameworks (MOFs) have potential applications in mercury capture due to their fantastic properties such as high porosity and high thermal stability. More important, their pore sizes and topology structures can be controlled through choosing different organic ligands in the syntheses. However, their mercury removal properties have not been studied so far. In this project, mercury absorption properties of selected known porous MOFs were studied, and the syntheses of new porous MOFs with functional groups for mercury absorption were investigated. Three known porous MOFs for mercury sorption properties were investigated. One of these MOFs, compound 3 shows a total efficiency greater than 90% in laboratory scale tests. Moreover, three new MOFs: [Cu(Br2BDC)2](HTEA)2 ， [Co2(BrBDC)(HCOO)2(DMF)2] and Zn2(BrBDC)(Trz)2•3H2O, (BrBDC = 2,5- dibromoterepthalicate, DMF =dimethylformamide, TEA = trimethylamine, Trz=1,2,4-triazole) were synthesized successfully. The first two compounds have two-dimensional structures, while the last compound contains three-dimensional channels with opening over 4.7 Å.
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McPherson, Matthew Joseph. "Control of water and toxic gas adsorption in metal-organic frameworks." Thesis, University of St Andrews, 2016. http://hdl.handle.net/10023/16489.
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The research presented in this thesis aims to determine the effectiveness of the uptake of toxic gases by several MOFs for future use in gas-mask cartridges, and to attempt to compensate for any deficiencies they show in “real-world” conditions. The main findings of this thesis confirm that MOFs are suitable candidates for the use in respirator cartridge materials and provide high capacity for adsorption of toxic gases like ammonia and STAM-1 in particular showed an impressive improvement in humid conditions, which normally decrease the performance of MOFs made from the same materials, such as HKUST-1. STAM-1's improved performance in humid conditions is attributed to the structural shift it displays upon dehydration and rehydration and this was shown to be the case in a structural analogue, CuEtOip, which was synthesised in the author's research group. This analogue was analysed using a combination of single crystal XRD and solid state MAS-NMR, both of which showed the structural change occurring and displays similar gas sorption behaviours, suggesting that this mechanism is the source of STAM-1's improved performance in humid conditions. This thesis also examines the “Armoured MOF” process and investigates the transferability of the process of deposition of mesoporous silica onto MOFs with vastly different properties and synthetic methods compared to those published in the original publication. Alongside this, attempts to protect MOFs using mesoporous silicates were investigated for their viability.
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Morabito, Joseph. "Kinetic Methods for Understanding Linker Exchange in Metal-Organic Frameworks." Thesis, Boston College, 2017. http://hdl.handle.net/2345/bc-ir:107593.
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Thesis advisor: Chia-Kuang (Frank) TsungExchange reactions have enabled a new level of control in the rational, stepwise preparation of metal-organic framework (MOF) materials. However, their full potential is limited by a lack of understanding of the molecular mechanisms by which they occur. This dissertation describes our efforts to understand this important class of reactions in two parts. The first reports our use of a linker exchange process to encapsulate guest molecules larger than the limiting pore aperture of the MOF. The concept is demonstrated, along with evidence for guest encapsulation and its relation to a dissociative linker exchange process. The second part describes our development of the first quantitative kinetic method for studying MOF linker exchange reactions and our application of this method to understand the solvent dependence of the reaction of ZIF-8 with imidazole. This project involved the collection of the largest set of rate data available on any MOF linker exchange reaction. The combination of this dataset with small molecule encapsulation experiments allowed us to formulate a mechanistic model that could account for all the observed kinetic and structural data. By comparison with the kinetic behavior of complexes in solution, we were able to fit the kinetic behavior of ZIF-8 into the broader family of coordination compounds. Aside from the specific use that our kinetic data may have in predicting the reactivity of ZIF linker exchange, we hope that the conceptual bridges made between MOFs and related metal−organic compounds can help reveal underlying patterns in behavior and advance the field
Thesis (PhD) — Boston College, 2017
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry
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Fujiwara, Yu-ichi. "Synthesis and Formation Mechanism of Carbon Materials from Porous Coordination Polymers." Kyoto University, 2018. http://hdl.handle.net/2433/232058.
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Gonzalez-Santiago, Berenice. "Synthesis and properties of scandium carboxylate metal-organic frameworks." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/6904.
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This work investigated the synthesis, characterisation and properties of known and novel scandium carboxylate Metal-organic Frameworks (MOFs). The first part reports the performance of these Sc-MOFs as Lewis acid catalysts. The porous MOF scandium trimesate MIL-100(Sc) and the scandium terephthalates such as MIL-101(Sc), MIL-88B(Sc) and MIL-68(Sc) (prepared as the Sc-analogue for the first time), and scandium biphenyldicarboxylate MIL-88D(Sc) were prepared and tested as Lewis acid catalysts. Chromium MIL-101 and MIL-100 and scandium-exchanged zeolites were prepared for comparison. Moreover, successful encapsulation of the phosphotungstate polyoxometalates (POMs) in the cavities of MIL-101(Sc) enhanced the stability of this material. These scandium and chromium MOFs, POM-MOF composites and scandium-exchanged zeolite were tested as heterogeneous catalysts in the carbonyl ene reaction between α-methyl styrene and ethyl trifluoropyruvate. This showed that MIL-100(Sc) was the best catalyst for this reaction, achieving a conversion of 99% to the desired product. The stabilized MIL-101(Sc) was also very active, but less selective for this reaction. Acetalisation of acetaldehyde was also studied, and in this reaction the isoreticular MOFs MIL-88(B) and MIL-88D(Sc) were the most active and selective catalysts. For this reaction, the activity of MIL-100(Sc) was low, which was attributed to reduce pore size and blockage. Functionalisation of the range of scandium terephthalates such as MIL-101(Sc), MIL-88B(Sc), MIL-68(Sc), Sc₂BDC₃,and MIL-53(Sc) particularly with –NH₂ groups, made up the second main part of this research. Solvothermal synthesis were performed at lower temperatures and using mixed solvents to synthesize these amino-terephthalate MOFs, often for the first time, and their adsorption properties were studied, particularly for the adsorption of CO₂. The synthesis of pure Sc₂(NH₂-BDC)₃ and Sc₂(Br-BDC)₃ was achieved for first time by a solvothermal route, lower temperatures, and mixed solvents. This approach yielded large crystals suitable for single crystal diffraction and microcrystal IR spectroscopy. Post-synthetic modification (PSM) of Sc₂(NH₂-BDC)₃ was explored by incorporation of NO₂-groups into the framework by solvent-assisted ligand exchange. The adsorption properties of functionalised and post-modified materials were compared with those of Sc₂BDC₃ and Sc₂(NO₂-BDC)₃ for methanol and hydrocarbons This study demonstrated that Sc₂BDC₃ and Sc₂(NH₂-BDC)₃ give the higher uptakes while the –Br and –NO₂ forms display shape selectivity for n-alkanes over iso-alkanes. Amino-functionalised MIL-53(Sc) was prepared for the first time using a mixed ligand approach, so that 10-20% of a second functionalised terephthalate ligand (NO₂, Br, -(OH)₂) was required for successful single phase synthesis in addition to amino-terephthalic acid. The materials were characterised using PXRD, TGA and gas adsorption, which confirms the samples show a range of behaviour for CO₂ adsorption. Notably, the `breathing´ behaviour is strongly dependent on the type of functionalisation. Finally, the exploratory synthesis of novel scandium MOFs, using isophthalic acid (IA) and its amino and nitro- derivatives, 2,5-furandicarboxylate (FDA) and the porphyrin tetra(carboxyphenyl)porphyrin (TCPP) as linkers was carried out and six novel materials were synthesized, three of which gave crystals large enough for their structure to be determined by single crystal diffraction. Further characterisation was carried out by PXRD, TGA and solid-state NMR. Some of these materials have been shown to be porous to CO₂ and N₂.
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Ji, Youngran. "Metal Organic Frameworks (MOFs) and Porous Organic Polymers (POPs) for Heterogeneous Asymmetric Catalysis." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/5868.
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The administration of enantiopure drugs brings advantages such as improved efficacy, more predictable pharmacokinetics and reduced toxicity from the point of view of the pharmaceutical area.[1] For this reason, a tremendous amount of supply and demand for enantiomeric pure compounds has been shown not only in market, but industry and academia.[2-4] According to the industry publication Genetic Engineering and Biotechnology News (GEN) in 2014, 22 billion dollars were accounted for enantiopure form of drugs such as Sovaldi® (Sofosbuvir), Crestor® (Rosuvastatin), and Advair® (fluticasone/salmeterol).
The fact that one enantiomer can be pharmacologically effective whereas the other enantiomer can be inactive or display non-desirable activity, chiral resolution and asymmetric synthesis research has broken out in recent years to obtain one desired stereoisomer. Enormous amounts of well-organized and rationalized research results for higher enantiomeric selectivity and efficiency has been reported with diverse chiral ligands and transition metals in academia.[5-10] However novelty-driven results from academic area does not meet the requirement in industry field for the practical issue, especially tedious separation process that require high cost and effort. In addition, methodologies developed with privileged chiral ligands and transition metal complexes leave a concern like undesired residue of trace amount of toxic metals in the products.
In this dissertation, two types of heterogeneous asymmetric catalyst were investigated to find the alternative that accommodates industrial requirement to obtain enantiomeric pure compounds and novelty-driven academic demands. Firstly, constructions of rationally designed metal organic frameworks (MOFs) using chiral BINOL-derived phosphoric acid ligands were achieved. Overall, catalytic reactions with ocMOFs showed lower enatioselectivity than their homogeneous counterparts, but one of the MOFs, ocMOF-1, was found to exhibit improved enantioselectivity than its homogeneous counterpart in the context of transfer hydrogenation reaction of benzoxazine. Lower enatioselectivity with ocMOFs was rationalized by the chiral environment change by the formation of frameworks in a computational study.
In addition, self-supported heterogenization of chiral BINOL-phosphoric acid was achieved by the Yamamoto coupling reaction, and by using catalytically active ocPOP-1 having nanoscopic channels, enantioselectivity was obtained up to 48% in transfer hydrogenation of N-PMP ketimine. Although extension of substituent groups at 3, 3' positions was expected to bring enhanced steric hindrance and to influence to enantioselectivity positively, lack of spatially well-defined interactions induced by this chiral environment change might have lowered the enantiomeric selectivity of the catalytic reaction using ocPOP-1 than its counterpart.
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Wharmby, Michael T. "Synthesis of porous metal phosphonate frameworks for applications in gas separation and storage." Thesis, University of St Andrews, 2012. http://hdl.handle.net/10023/3450.
Full textAbstract:
Porous metal phosphonate framework materials were synthesised by solvothermal reaction of bis(α-aminomethylenephosphonic acid) ligands with divalent and trivalent metal cations. The syntheses and characterisation by NMR and, where possible, single crystal X-ray diffraction of seven bisphosphonic acid ligands, including N,N′-piperazinebis(methylenephosphonic acid) (H₄L), its racemic and enantiopure (R) 2-methyl (H₄L′ and R-H₄L′) and 2,5-dimethyl (H₄L′′) derivatives, and N,N′-4,4′-bipiperidinebis(methylenephosphonic acid) (H₄LL) are reported. Syntheses of the known phase Y₂(LH₂)₃·5H₂O and the new phases, STA-13(Y) (St Andrews microporous material No. 13) and Y₂(R-L′H₂)₃·4H₂O, from reactions of Y(AcO)₃ with H₄L, H₄L′ and R-H₄L′ respectively are reported. The as-prepared and dehydrated structures of each phase have been determined from either laboratory or synchrotron powder X-ray diffraction data. Reaction of Y(AcO)₃ and H₄L′′ is shown to form a phase with a different structure. The features determining which structure crystallises are discussed. Syntheses of other rare-earth forms of STA-13 (Sc³⁺, Gd³⁺–Yb³⁺) and the porosity of each phase to N₂ are reported. STA-13(Y) is the most porous form with loadings of ∼3 mmol g⁻¹ and ∼4 mmol g⁻¹ for N₂ and CO₂ respectively. MIL-91(Fe) was synthesised for the first time from reactions of Fe³⁺ cations with H₄L. Its structure was confirmed by Rietveld refinement, but it was not porous. The first syntheses of [Fe₄L₁.₅(AcO)₁.₅(OH,H₂O)₃]·0.5NH₄5.5H₂O (L= L or L′) are reported, from reactions of H₄L or H₄L′ in the presence of an excess of Fe³⁺ cations. The phase is related to a previously reported Co phase. The synthesis of divalent metal bisphosphonate STA-12(Mg) (Mg₂(H₂O)₂L·5.6H₂O) was reported for the first time and its structure determined from single crystal X-ray diffraction. The dehydration behaviour of this material was compared with the known forms of STA-12. STA-12(Mg) is porous to both N₂ (∼5.5 mmol g⁻¹) and CO₂ (~ 8.5 mmol g⁻¹). Reaction of H₄LL with Co²⁺ and Ni²⁺ gave two materials isoreticular with STA-12, labelled STA-16(Co) and STA-16(Ni). The structures of both materials were solved from synchrotron powder X-ray diffraction data. On dehydration, STA-16(Co) undergoes a reversible structural transition to an unknown structure. By contrast, STA-16(Ni) retains the same symmetry in the dehydrated form and its structure was determined from synchrotron powder X-ray diffraction data. Both materials are porous to N₂, with an uptake of up to 22.2 mmol g⁻¹, and CO₂ with maximum loading of 21.7 mmol g⁻¹. NLDFT analysis of N₂ adsorption data confirm the crystallographically determined pore radii. Syntheses of other frameworks with divalent cations and initial reactions of H₄LL with trivalent cations are also reported.
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Schwartz, Heidi Annemarie [Verfasser]. "Metal-Organic Frameworks as Crystalline Porous Hosts for Photoactive Molecules / Heidi Annemarie Schwartz." München : Verlag Dr. Hut, 2018. http://d-nb.info/1168534356/34.
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Wiersum, Andrew. "Developing a strategy to evaluate the potential of new porous materials for the separation of gases by adsorption." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4817/document.
Full textAbstract:
Les Metal-Organic Framework (MOF) sont des adsorbants très prometteurs pour la séparation des gaz. Formés de centres métalliques reliés par des ligands organiques, ces matériaux présentent une structure organisée avec des pores de taille contrôlée ainsi que des surfaces et des volumes poreux très élevées. La possibilité de faire varier à la fois le centre métallique et le ligand organique donne aux MOFs une très grande diversité qu'on ne retrouve pas chez les zéolithes et les charbons actifs.L'objectif de cette étude a été d'évaluer le potentiel des MOFs en tant qu'adsorbants pour quatre procédés de séparation de gaz. En raison du grand nombre de MOFs disponibles, il a été nécessaire d'élaborer une stratégie pour identifier les matériaux les plus prometteurs dans chaque cas. Cette méthodologie comprend quatre étapes : une étape de criblage, une étape expérimentale, une étape de calcul et une étape d'évaluation.Pour l'étape de criblage, un nouvel appareil dit « à haut débit » a été développé pour mesurer des isothermes approximatives. Ensuite, un certain nombre de matériaux ont été retenus pour faire une étude plus approfondie de leurs propriétés d'adsorption. Des isothermes très précises ont été mesurées par gravimétrie tandis que les enthalpies d'adsorption ont été obtenues par microcalorimétrie. Dans l'étape de calcul, le modèle IAST a été utilisée pour prédire les sélectivités à partir des données en gaz pur. Enfin, les adsorbants ont été classés à l'aide d'un nouveau paramètre de sélection qui regroupe la sélectivité, la capacité efficace et l'enthalpie d'adsorption, où l'importance de chacun des paramètres peut être ajustée en fonction des besoins du procédéMetal-Organic Frameworks (MOFs) are seen to be one of the most promising classes of adsorbents for gas separations. Consisting of metal clusters connected by organic linkers to form a fully crystalline network, these materials have record breaking surface areas and pore volumes as well as a wide variety of pore structures and sizes. This, coupled with the possibility to use virtually any transition metal as well as functionalized linkers, gives MOFs the chemical and physical versatility often lacking in traditional adsorbents such as zeolites and activated carbons.The purpose of this study was to evaluate the potential of MOFs as adsorbents for four gas separations of interest to the petrochemical industry. Because of the diversity and number of MOFs available, a methodology was needed to help identify the most promising materials in each case. The proposed methodology comprises four stages: a screening step, an experimental step, a computational step and finally an evaluation step. For the first stage, a high-throughput setup was developed to measure rough adsorption isotherms. A number of materials were then selected for a more thorough investigation of their adsorption properties. Highly accurate isotherms were measured gravimetrically while precise adsorption enthalpies were obtained by microcalorimetry. Step three involved predicting the co-adsorption behaviour from the pure gas isotherms using the Ideal Adsorbed Solution Theory. Finally, the adsorbents were ranked based on a new selection parameter regrouping selectivity, working capacity and adsorption enthalpy where the importance of each term can be adjusted depending on the requirements of the process
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Dawson, Daniel M. "Combined theoretical and experimental investigations of porous crystalline materials." Thesis, University of St Andrews, 2014. http://hdl.handle.net/10023/7053.
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This thesis combines solid-state nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction (XRD), chemical synthesis, isotopic enrichment and density-functional theory (DFT) calculations to provide insight into a number of microporous materials. The first class of materials studied is metal-organic frameworks (MOFs), where the presence of paramagnetic ions has a range of effects on the ¹³C NMR spectra, depending on the nature of the ligand-metal interactions. For the Cu²⁺-based MOFs, HKUST-1 and STAM-1, the assignment of the NMR spectra is non-intuitive, and unambiguous assignment requires specific ¹³C labelling of the organic linker species. It is shown that ¹³C NMR spectra of these two MOFs could act as a sensitive probe of the nature of “guest” molecules bound to the Cu²⁺. The second class of materials is aluminophosphates (AlPOs). It is shown that, using a series of relatively simple linear relationships with the crystal structure, the NMR parameters calculated by DFT (with calculation times of several hours) can be predicted, often with experimentally-useful accuracy, in a matter of seconds using the DIStortion analysis COde (DISCO), which is introduced here. The ambient hydration of the AlPO, JDF-2, to AlPO-53(A) is shown to occur slowly, with incomplete hydration after ~3 months. The resulting AlPO-53(A) is disordered and some possible models for this disorder are investigated by DFT. The final class of materials is gallophosphates (GaPOs), particularly GaPO-34 and related materials. The two as-prepared forms of GaPO-34 are characterised by solid-state NMR, and their calcination investigated by TGA and in-situ powder XRD. An unusual dehydrofluorinated intermediate phase is isolated and characterised for the first time by solid-state NMR. The fully calcined material is shown to be stable under anhydrous conditions, but hydrates rapidly in air. The hydrated material is stable under ambient conditions, but collapses upon heating. Partial dehydration without collapse is achieved by gentle heating or room-temperature evacuation. The impurity phases, GaPO₄ berlinite and GaPO-X are investigated by solid-state NMR and, while the structure of GaPO-X remains unknown, much structural information is obtained.
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Young, Allison Patricia. "Using Lattice Engineering and Porous Materials Gating to Control Activity and Stability in Heterogeneous Catalysis." Thesis, Boston College, 2018. http://hdl.handle.net/2345/bc-ir:108207.
Full textAbstract:
Thesis advisor: Chia-Kuang TsungHeterogeneous catalysis is a critical field for chemical industry processes, energy applications, and transportation, to name a few. In all avenues, control over the activity and selectivity towards specific products are of extreme importance. Generally, two separate methods can be utilized for controlling the active surface areas; a below and above the surface approach. In this dissertation, both approaches will be addressed, first starting with controlling the active sites from a below approach and moving towards control through sieving and gating effects above the surface. For the first part half, the control of the product selectivity is controlled by finely tuning the atomic structures of nanoparticle catalysts, mainly Au-Pd, Pd-Ni-Pt, and Pd Ni3Pt octahedral and cubic nanoparticle catalysts. Through these shaped core-shell, occasionally referred to as core@shell, particles the shape is maintained in order to expose and study certain crystal facets in order to obtain a more open or closed series of active sites. With the core shell particles, the interior core particle (Au and Pd) is used for the overall shape but also to expansively/compressively strain the outer shell layer. By straining the surface, the surface electronic structure is altered, by raising or lowering the d-band structure, allowing for reactants to adsorb more or less strongly as well as adsorb on different surface sites. For the below the surface projects, the synthesized nanoparticle catalyst are used for electrochemical oxidation reactions, such as ethanol and methanol oxidation, in order to study the effect of the core and shell layers on initial activity, metal migration during cycling, as well as particle stability and activity using different crystal structures. In particular, the use of core shell, alloyed, and intermetallic (ordered alloys) particles are studied in more detail. In the second half of this dissertation, control of the selectivity will be explored from the top down approach; in particular the use of metal organic framework (MOF) will be utilized. MOF, with its inherent size selective properties due to caging effects from the chosen linkers and nodes, is used to coat the surface of catalysts for gas, liquid, and electrochemical catalysis. By using nanoparticle catalyst, the use of MOF, more explicitly the robust zirconium based UiO-66, as a crystalline capping agent is first explored. By incorporating both the nanoparticle and UiO-66 amino functionalized precursors in the synthesis, the nanoparticles are formed first and followed by coating in UiO-66-NH2, where the amino group acts as an anchor, completely coating the particles. The full coating is tested through size selective alkene hydrogenations with the NP surface further tested by liquid phase selective aldehyde hydrogenations; the UiO-66-NH2 pores help to guide the reactant molecule in a particular orientation for the carbonyl to interact rather than the unsaturated C=C bond. This approach is taken for more complex hybrid structures for electrochemical proton exchange membrane fuel cell (PEMFC) conditions. Through the gating effects, the UiO-66 blocks the Pt surface active sites from poisonous sulfonate groups off of the ionomer membrane while simultaneously preventing aggregation and leaching of Pt atoms during electrochemical working conditions
Thesis (PhD) — Boston College, 2018
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry