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1
Tahier, Tayyibah. "Crystal engineering of mixed-ligand metal-organic frameworks." Master's thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/22913.
Full textAbstract:
Research of solid state complexes has grown and developed exponentially over the past few years in terms of supramolecular chemistry and crystal engineering. The synthesis and characterisation of metal organic frameworks (MOFs) have attracted widespread attention owing to their potential in various applications. This includes gas sorption, which could aid in alleviating serious environmental issues such as global warming by sequestrating greenhouse gases. Advances in the design of these materials using the mixed ligand approach add to variation in structures and thus provide a further means of tailoring of properties. A novel two dimensional, mixed ligand MOF has been synthesised based on 1,3,5 benzenetricarboxylic acid, 4,4' bipyridine N,N' dioxide and zinc sulfate with the formula [Zn3(BTC)(4,4' bpdo)(OH)(SO4)(H2O)3]n·n(H2O)2.33 (1). The 2D layers of 1 arrange in a polar fashion with adjacent layers forming isolated cavities. Variable temperature powder X ray diffraction (VT PXRD) analysis showed that the crystallinity of the compound was retained and the crystalline phase remained unchanged as the temperature was increased. Variable temperature single crystal X ray diffraction (VT SCXRD) analysis of 1 revealed that the dehydration and rehydration processes occur via single crystal to single crystal transformations. Water vapour sorption experiments showed a type I isotherm, typical of microporous materials. A two dimensional, interpenetrated, mixed ligand MOF has been synthesised based on 5 nitro 1,3 benzenedicarboxylic acid, 1,2 bis(4 pyridyl)ethane and cadmium nitrate with the formula [Cd(bpe)1.5nbdc]·DMF (2). VT PXRD analysis shows subtle differences in the compound as the temperature is increased. VT SCXRD experiments show that the most notable change in the structure occurs at 373 K. These changes include the removal of the guest molecule and a change in the crystal system, along with changes in the orientation of the pyridyl ring of the organic ligand. Carbon dioxide sorption experiments at 195 K showed a type IV isotherm, which is usually associated with mesoporous materials. Both 1 and 2 were synthesised using the solvothermal method and fully characterised using X ray diffraction studies (SCXRD, PXRD, VT SCXRD and VT PXRD), thermal analysis (thermogravimetric, differential scanning calorimetry, hot stage microscopy), elemental analysis and FT IR spectroscopy. The porosity of the compounds was tested using carbon dioxide (273 K and 193 K), nitrogen, water vapour and liquid sorption experiments.
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Gcwensa, Nolwazi. "Porosity studies of isoreticular mixed-ligand metal-organic frameworks." Master's thesis, Faculty of Science, 2019. http://hdl.handle.net/11427/31385.
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The syntheses of four novel mixed-ligand metal-organic frameworks (MOFs) are reported. Isoreticular, Zn(II)-based mixed-ligand MOFs with formulae [Zn(μ2-ia)(μ2-bpe)]n·nDMF (1) and [Zn(μ2-mia)(μ2- bpe)]n·nDMF (2), where ia = isophthalate, mia = 5-methoxyisophthalate, bpe = 1,2-bis(4-pyridyl)ethane and DMF = N,N’-dimethylformamide were synthesised and characterised. Both compounds 1 and 2 exhibit sql, 2-periodic, 2D net coordination layers. Catenation of neighbouring frameworks form 2-fold interpenetrated bilayers which are interdigitated resulting in channel voids containing DMF. Experimental void calculations indicate 2′ has larger void space per unit cell than 1′; however, experimentally, 1′ showed higher water vapour and carbon dioxide 195 K sorption as well as significant hysteresis upon desorption of carbon dioxide 195 K. This hysteresis behaviour of 1′ is interchanged with 2′ for water vapour sorption at 298 K. Sorption isotherm inflection points indicate that structural changes occur, and empirical evidence point to weak bilayer···bilayer interactions in 1′ which allow the separation of the bilayers as well as the limiting effect on structural changes of the methoxy group present in 2′. Isoreticular mixed-ligand Cd(II)-based MOFs with formulae [Cd(μ2-mia)(μ2-bpe)1.5]n·n(DMF)0.5n(H2O)0.5 (3) and [Cd(μ2-nia)(μ2-bpee)1.5]n·nDMF (4), where nia = 5-nitroisophthalate and bpee = 1,2-bis(4-pyridyl)ethylene were also synthesised and characterised. Both compounds 3 and 4 exhibit sql, 2-periodic, 3D net coordination layers with disorder around a single bpe or bpee ligand. These structures are compared to published structure [Cd(bpee)1.5(nbdc)]n·nDMF (JECRAN) which is isoreticular to both MOFs. Activation of 4 and JECRAN occurs via single-crystal-to-single-crystal transformations. Potential and actual void space calculations indicate that 4′ has a larger void space than 3′ and JECROB. Liquid sorption experiments revealed that 3′ and 4′ showed affinities for different solvents. Although carbon dioxide 195 K sorption for 4′ is initially higher than for JECROB, structural changes, indicated by sorption isotherm inflection points, allow JECROB to adsorb more carbon dioxide than 4′
3
Mitchell, Laura. "Metal organic frameworks as Lewis acid catalysts." Thesis, University of St Andrews, 2014. http://hdl.handle.net/10023/6392.
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Lewis acids are widely used in the pharmaceutical industry, generally homogeneously, to perform reactions such as C-C or C=N bond formation and acetalisation. Typically, metal salts such as those of Ti, Fe and especially Sc are used, the last typically as the triflate. Metal organic frameworks (MOFs) containing such metals should act as heterogeneous, removable and reusable catalysts for similar reactions if they can be prepared in stable forms and with large, open pores and metal cation sites that can be rendered coordinatively unsaturated. Families of novel MOFs with different structure types and cations have therefore been prepared and their activity has been examined in carbonyl ene C-C bond forming reactions, Friedel-Crafts-Michael additions and in imine formation reactions. Their activities have been compared with those of the well-known HKUST-1(Cu), MIL-100(Fe) and MIL-101(Cr) solids examined as catalysts previously. In particular, divalent transition metal bisphosphonates and dicarboxylates with pore sizes from 10 – 20 Å and scandium carboxylates (MIL-68(Sc), MIL-88D(Sc), MIL-100(Sc), MIL-101(Sc)) have been tested. Synthetic procedures were optimised according to commercial constraints for the known MOFs STA-12(Ni) and MIL-100(Sc). While good activities are observed for Ni-based MOFs and in a number of the scandium-based solids, MIL-100(Sc) is by far the best Lewis acid catalyst for a range of reactions. In particular, MIL-100(Sc) is very active even when used without pre-dehydration, is readily recyclable with minor loss of activity and shows fully heterogeneous activity. It outperforms both MIL-100(Fe) and MIL-101(Cr), each commonly reported as versatile catalysts in the literature. Careful synthesis of bulky substrates shows that the activity is derived from reactions within the internal pore system. Furthermore, MIL-100(Sc) is able to perform tandem reactions - such as dehydration followed by carbonyl ene reaction - in which the Lewis acid sites catalyse two steps. The Lewis acidic sites of the excellent Lewis acid catalyst MIL-100(Sc) has been examined in detail by in situ IR using adsorption of CO and CD₃CN as probe molecules and compared with other MIL-100 materials. The work has been extended to the examination of MOFs containing two different metals, by substitutional approaches within the metal nodes (e.g. Sc-Al, Sc-Fe, Sc-Cr, Sc-Ni, Sc-Co within the trimeric M₃O(O₂C-)₆ nodes of MIL-100). In addition, series of Sc-Fe MIL-100 materials have been prepared that contain α-Fe₂O₃ nanoparticles in the pores of the structure. These composites show higher specific catalytic activity for Lewis acid catalysis than MIL-100(Sc), even though some scandium has been replaced with iron: the origin of this behaviour is discussed. MIL-100(Sc/Fe) has also been explored as a bifunctional catalyst in tandem Friedel-Crafts-oxidation reactions. MIL-100(Sc₆₀/Fe₄₀) was found to give exceptionally high conversions in the Friedel-Crafts-oxidation tandem reaction of 2-methyl indole and ethyl trifluoropyruvate to form a ketone, outperforming the many other materials tested and giving the best balance of the two different types of catalytic sites required to catalyse the reaction. MIL-100(Sc) has also been prepared containing 50% of mono-fluorinated trimesate ligands in the framework for the first time. This fluorinated MIL-100(Sc) has been post-synthetically modified by addition of a di-phenylphosphino group as confirmed by solid state NMR. This can act as a starting point for the future generation of MOF-supported metal phosphine catalysts.
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Nayak, Nayan Nagesh. "Development of mixed matrix membranes with metal - organic framework and ionic liquids for biogas upgrading." Master's thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10419.
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Dissertation presented to Faculdade de Ciências e Tecnologia, Universidade Nova
de Lisboa for obtaining the master degree in
Membrane EngineeringThe EM3E Master is an Education Programme supported by the European Commission, the European Membrane Society (EMS), the European Membrane House (EMH), and a large international network of industrial companies, research centers and universities
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Doheny, Patrick William. "Elucidation of the Properties of Electroactive Metal-Organic Framework Materials via a Combined Experimental and Computational Approach." Thesis, The University of Sydney, 2019. https://hdl.handle.net/2123/21894.
Full textAbstract:
The work presented in this dissertation details a systematic study of the fundamental and applied properties of electroactive metal-organic framework (MOF) materials from first design principles utilising a combined structural, electrochemical, spectroelectrochemical and computational approach. The structure-property relationships arising from the incorporation of organic-based electroactive ligands, specifically topology-driven through-space charge transfer and radical delocalisation, into a series of 3-dimensional MOF materials were investigated from both a fundamental and applied perspective. Chapter 3 details the fundamental study of a previously unreported method of charge transfer in MOF materials focused on through-space intervalence charge transfer (IVCT). Two novel ligands, BPPTzTz and BPPFTzTz, incorporating the electron accepting thiazolo[5,4-d]thiazole (TzTz) moiety were synthesised and extensively characterised. The structure-property relationships within these materials enabled the access of a topology characterised by close proximity of cofacially stacked TzTz ligands. Reduction of the TzTz ligands of these frameworks led to the formation of a mixed-valence material exhibiting unusual IVCT properties that could be accessed in situ electrochemically or ex situ via chemical reduction. The mixed-valence properties demonstrated by these materials were extensively characterised by using a variety of electrochemical, spectroelectrochemical and computation techniques to derive a mechanism by which this through-space IVCT operates. Radical anion spin delocalisation and its effects on spin state switching is the focus of Chapter 4 concerning the synthesis of an Fe2+ spin crossover (SCO) Hofmann material incorporating the redox-active DPTzTz ligand. An extensive structural, electrochemical, spectroelectrochemical and computational study was carried out on this framework in addition to studies of its magnetic properties. The structure was found to exhibit an abrupt, single-step SCO transition from high spin (HS) to low spin (LS) Fe2+ upon cooling. The structural changes upon desolvation of the de novo structure was extensively characterised using single crystal X-ray diffraction which revealed a series of irreversible structural phase transitions. The SCO properties of the desolvated material were characterised by an incomplete, single-step transition with hysteresis widths comparable with the highest reported in three-dimensional Hofmann materials. The framework was found to successfully retain the electrochemical properties of the discrete DPTzTz ligand upon self-assembly and using chemical reduction, the SCO properties of the material were successfully modified relative to the neutral parent phase. The results of this study demonstrated the successful application of a previously unreported method of modifying the magnetic properties of a solid state SCO material. An applied study of an electroactive MOF targeting gas sorption applications is the focus of Chapter 5, detailing a topological analogue of the well-known MOF-74 material incorporating the electron accepting DSNDI ligand. The neutral parent phase was characterised using a variety of electrochemical, spectroelectrochemcial and computational methods which demonstrated a porous MOF stable to both electrochemical and chemical reduction. The gas sorption properties of this framework, which contained open metal sites upon activation, were investigated with respect to H2, CH4 and CO2. Chemical reduction of this material yielded a material containing ligand-based radical anions and Li+ counterions; the sorption properties were successfully retained, however a significant enhancement of the CO2 isosteric heat of adsorption was observed. The enhanced CO2 binding enthalpy of ~45.0 kJ/mol was comparable to the highest performing member of the parent MOF-74 series and was found to be a promising candidate as a CO2 sorbent material. Fundamental studies of this material were also carried out with respect to its ability to form donor-acceptor (D-A) units within the solid state structure. A series of six electron donating molecules were infiltrated into the structure upon which donor-acceptor pairs were successfully established. The resulting D-A MOFs were characterised ex situ using UV-Vis-NIR and EPR spectroscopies which confirmed the presence of radical species and D-A charge transfer within the structure. DFT calculations were performed to further elucidate the nature of these D-A interactions with the degree of partial charge transfer also examined via these methods. The successful formation of donor-acceptor complexes in the framework structure demonstrated a strategy by which the conductive and sorption properties of the material might be modified by careful choice and energy level matching of guest electron donor with the electron accepting DSNDI ligands of the bulk framework. This work has demonstrated a series of multifunctional MOF materials with novel properties accessible by virtue of their intrinsic redox capabilities. Insight into the electronic properties of MOF materials and their corresponding structure-property relationships has been achieved with exciting results demonstrated. The fundamental investigations here serve as an invaluable platform for the development of future multifunctional electroactive MOF materials targeting commercial and industrial applications.
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Shahid, Salman. "Polymer-Metal Organic Frameworks (MOFs) Mixed Matrix Membranes For Gas Separation Applications." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS141/document.
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Le comportement plastifiant de polymères purs a été bien étudié dans la littérature. Toutefois, il n'y a eu que peu d'études concernant les membranes à matrices mixtes (MMM). Dans le chapitre 2 de cette thèse, le comportement plastifiant de MMM préparés à partir de nanoparticules mésoporeuses Fe(BTC) et du polymère Matrimid® est étudié avec un gaz pur ou en mélange. Les réseaux métaux-organiques (MOF) sous forme particulaires ont présenté une relativement bonne compatibilité avec le polymère. L'incorporation de Fe(BTC) dans du Matrimid® a permis d'augmenter la perméabilité et la sélectivité des membranes. Pour de faibles pressions de 5 bars, les MMM ont une perméabilité au CO2 de 60% plus grande ainsi qu'une sélectivité de 29% plus grande à comparer à la sélectivité idéale de membranes Matrimid®. Il a été observé que la présence de particules Fe(BTC) retardait l'effet plastifiant vers de plus grandes pressions. De plus, cette pression augmente avec le taux de MOF au sein du matériau. Ce retard est attribué à la mobilité réduite des chaînes polymères dans l'entourage des particules Fe(BTC). Egalement, pour des concentrations en MOF plus élevées, les membranes présentent une sélectivité plus ou moins constante sur toute la gamme de pression étudiée. Le chapitre 3 présente ensuite la préparation et le caractère plastifiant des MMMs basées sur trois types de MOFs (MIL-53(Al) (MOF « repirant »), ZIF-8 (MOF « flexible ») and Cu3(BTC)2 (MOF « rigide »)) dispersés dans le Matrimid®. Les performances en gaz pur ou en mélange ont été étudiées en fonction de la quantité de MOF introduite. Parmi les trois systèmes MOF-MMM, les membranes avec le Cu3(BTC)2 ont présenté la plus haute sélectivité alors que les membranes avec du ZIF-8 ont montré une plus grande perméabilité. Ces améliorations sont essentiellement le fait de la structure cristalline du MOF et de son interaction avec les molécules de CO2. Le chapitre 4 décrit la préparation de membranes à base de mélange Matrimid® polyimide (PI)/polysulfone (PSF) contenant des particules de ZIF-8 pour la séparation gazeuse à haute pression. Un mélange optimisé avec un rapport PI/PSF de 3:1 a été utilisé pour une étude sur la stabilité et la performance de ces MMMs incorporant différentes concentration de ZIF-8. PI et PSF étant miscibles, une bonne compatibilité avec les particules de ZIF-8 est observée. Les MMMs PI/PSF-ZIF-8 ont démontré une amélioration significative de la perméabilité en CO2 lors de l'augmentation de la concentration en ZIF-8, ce qui a été attribué à une augmentation modérée de la capacité de sorption et à une diffusion plus rapide au travers des particules de ZIF-8. Lors des mesures en gaz purs, les membranes PI/PSF (3:1) ont présenté une plastification vers 18 bars alors que l'introduction de ZIF-8 repousse cette valeur à 25 bars. En mélange de gaz, les MMMs PI/PSF-ZIF-8 ont abouti à une suppression de la plastification comme l'a confirmé une mesure constante de la perméabilité et de la sélectivité du CH4, et cet effet est plus accentué avec l'augmentation de la concentration en ZIF-8. Les résultats en séparation des gaz avec les MMMs PI/PSF-ZIF-8 montrent une performance supérieure à celle du Matrimid® ce qui laisse augurer un élargissement du spectre d'application de ces membranes, particulièrement pour la séparation du CO2 à haute pression. Dans le chapitre 5, une nouvelle voie de préparation des MMMs via la fusion contrôlée de particules a été introduite. La modification du Matrimid® par du 1-(3-aminopropyl)-imidazole a permis d'améliorer considérablement la compatibilité avec les particules de ZIF-8. Il a ainsi été possible de préparer des MMMs contenant 30% de MOF sans perte de sélectivité. En augmentant la concentration en ZIF-8, les MMMs ont de meilleures performances dans la séparation de mélange CO2/CH4 à comparer au polymère initial. La perméabilité a augmenté de plus de 200% avec une augmentation de 65% de sélectivité pour le mélange CO2/CH4The plasticization behavior of pure polymers is well studied in literature. However, there are only few studies on the plasticization behavior of mixed matrix membranes. In Chapter 2 of this thesis, pure and mixed gas plasticization behavior of MMMs prepared from mesoporous Fe(BTC) nanoparticles and the polymer Matrimid® is investigated. All experiments were carried with solution casted dense membranes. Mesoporous Fe(BTC) MOF particles showed reasonably good compatibility with the polymer. Incorporation of Fe(BTC) in Matrimid® resulted in membranes with increased permeability and selectivity. At low pressures of 5 bar the MMMs showed an increase of 60 % in CO2 permeability and a corresponding increase of 29 % in ideal selectivity over pure Matrimid® membranes. It was observed that the presence of Fe(BTC) particles increases the plasticization pressure of Matrimid® based MMMs. Furthermore, this pressure increases more with increasing MOF loading. This delay in plasticization is attributed to the reduced mobility of the polymer chains in the vicinity of the Fe(BTC) particles. Also, at higher Fe(BTC) loadings, the membranes showed more or less constant selectivity over the whole pressure range investigated. Chapter 3 subsequently presented the preparation and plasticization behavior of MMMs based on three distinctively different MOFs (MIL-53(Al) (breathing MOF), ZIF-8 (flexible MOF) and Cu3(BTC)2 (rigid MOF)) dispersed in Matrimid®. The ideal and mixed gas performance of the prepared MMMs was determined and the effect of MOF structure on the plasticization behavior of MMMs was investigated. Among the three MOF-MMMs, membranes based on Cu3(BTC)2 showed highest selectivity while ZIF-8 based membranes showed highest permeability. The respective increase in performance of the MMMs is very much dependent on the MOF crystal structure and its interactions with CO2 molecules. Chapter 4 described the preparation of Matrimid® polyimide (PI)/polysulfone (PSF)-blend membranes containing ZIF-8 particles for high pressure gas separation. An optimized PI/PSF blend ratio (3:1) was used and performance and stability of PI/PSF mixed matrix membranes filled with different concentrations of ZIF-8 were investigated. PI and PSF were miscible and provided good compatibility with the ZIF-8 particles, even at high loadings. The PI/PSF-ZIF-8 MMMs showed significant enhancement in CO2 permeability with increased ZIF-8 loading, which was attributed to a moderate increase in sorption capacity and faster diffusion through the ZIF-8 particles. In pure gas measurements, pure PI/PSF blend (3:1) membranes showed a plasticization pressure of ~18 bar while the ZIF-8 MMMs showed a higher plasticization pressures of ~25 bar. Mixed gas measurements of PI/PSF-ZIF-8 MMMs showed suppression of plasticization as confirmed by a constant mixed gas CH4 permeability and a nearly constant selectivity with pressure but the effect was stronger at high ZIF-8 loadings. Gas separation results of the prepared PI/PSF-ZIF-8 MMMs show an increased commercial viability of Matrimid® based membranes and broadened their applicability, especially for high-pressure CO2 gas separations. In Chapter 5, a novel route for the preparation of mixed matrix membranes via a particle fusion approach was introduced. Surface modification of the polymer with 1-(3-aminopropyl)-imidazole led to an excellent ZIF-8-Matrimid® interfacial compatibility. It was possible to successfully prepare MMMs with MOF loadings as high as 30 wt.% without any non-selective defects. Upon increasing the ZIF-8 loading, MMMs showed significantly better performance in the separation of CO2/CH4 mixtures as compared to the native polymer. The CO2 permeability increased up to 200 % combined with a 65 % increase in CO2/CH4 selectivity, compared to the native Matrimid®. Chapter 6 finally discussed the conclusions and directions for future research based on the findings presented in this thesis
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Benzaqui, Marvin. "Synthesis of Metal-Organic Framework nanoparticles and mixed-matrix membrane preparation for gas separation and CO2 capture." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLV075/document.
Full textAbstract:
La séparation CO2/N2 et H2/CO2 permet de limiter le rejet de CO2 dans l’atmosphère issu des gaz industriels et les membranes présentent de nombreux avantages tant sur le plan économique que pratique. Les membranes polymère sont faciles à mettre en forme mais un compromis entre perméabilité et sélectivité doit généralement être trouvé : pour améliorer les performances, des membranes à matrice mixte (MMM) incorporant des MOFs (matériaux hybrides poreux cristallisés) dispersés dans la phase polymère ont été proposées. A la différence des matériaux poreux inorganiques, les MOFs ont une meilleure compatibilité avec la matrice polymère du fait de leur caractère hybride organiqueinorganique. Dans le cadre de cette thèse, des polycarboxylates de Fe3+ et Al3+ poreux, stables à l’eau, et possédant de bonnes propriétés d’adsorption sélective du CO2 ont été synthétisés en milieu aqueux et mis à l’échelle de quelques grammes. Deux nouveaux polycarboxylates de Fe3+ poreux fonctionnalisés par des fonctions -COOH libres ont été obtenus à température ambiante. Pour l’un d’entre eux, la structure a été déterminée par diffraction des rayons X. Une deuxième partie de la thèse a été consacrée à la synthèse de nanoparticules de MOFs avec un bon rendement. Une partie importante de ce travail a porté sur le contrôle de la taille et la morphologie des nanoparticules de MIL-96(Al). Ce travail a conduit à la préparation de MMMs à base de MIL-96(Al) dont les performances sont supérieures à la membrane pure polymère pour la séparation CO2/N2. La dernière partie de ce travail de thèse a porté sur l’étude physico-chimique de la compatibilité entre le ZIF-8 et deux polymères (PVA et PIM-1). Ce travail a consisté à effectuer une caractérisation complète de solutions colloïdales MOFs/polymère en couplant plusieurs techniques (DLS, TEM, SAXS). Cette étude a montré que la compatibilité MOF/polymère est très dépendante de la chimie de surface des MOFs et des propriétés physico-chimiques du polymère (rigidité, caractère hydrophile/hydrophobe…)CO2 capture and storage (CCS) is of high economical and societal interest. CO2/N2 andH2/CO2 separations are able to limit atmospheric CO2 emissions produced by industrial exhausts andmembranes present numerous economical and practical advantages. Polymer membranes are easy toprocess and possess interesting mechanical properties. However, there is a trade-off to make betweenpermeability and selectivity. Mixed-matrix membranes (MMM) based on MOFs (porous crystallinehybrid materials) have been proposed to boost the performances of polymer membranes for CO2capture. In comparison to other inorganic porous materials, one may expect that the compatibilitybetween MOFs and polymers is enhanced due to the hybrid character of MOFs.In this work, porous water stable polycarboxylate MOFs based on Fe3+ and Al3+ with promisingproperties for CO2 adsorption were synthesized for large-scale production using water as the mainsolvent. Two new porous polycarboxylate Fe3+ MOF bearing free -COOH groups in the frameworkwere obtained at room temperature as nanoparticles. The crystallographic structure of one of thesematerials was determined by single crystal X-ray diffraction. A second part of the thesis was devotedto the synthesis of MOFs nanoparticles with good yield. We focused our attention on the control of thediameter and morphology of MIL-96(Al) nanoparticles. This study led to the preparation of MMMsbased on MIL-96(Al) with promising properties for CO2/N2 separation. Finally, the compatibilitybetween MOF particles and polymers was studied for two systems (ZIF-8/PIM-1 and ZIF-8/PVOH),showing the influence of the surface chemistry of MOFs and the physico-chemical properties ofpolymer on the matching between MOFs and polymers
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Khdhayyer, Muhanned. "Mixed matrix membranes comprising metal organic frameworks and high free volume polymers for gas separations." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/mixed-matrix-membranes-comprising-metal-organic-frameworks-and-high-free-volume-polymers-for-gas-separations(172f6a4f-a531-44ae-979c-bbbd170f33db).html.
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This research aimed to develop new composite membranes using a polymer of intrinsic microporosity (PIM-1) and metal organic frameworks (MOFs) for use in gas separations. PIM-1 was successfully synthesised using the high temperature method (40 min, 160 oC) and the resulting polymer was cast into membranes. PIM-1 membranes were chemically modified by reacting hexamethylenediamine (HMDA) with the nitrile group of PIM-1 to form HMDA-modified PIM-1 membranes. Surfaces of PIM-1 membranes were also modified by basic hydrolysis to form amide-modified PIM-1 membranes. These polymer materials were characterized by different techniques (GPC, NMR, ATR-IR, TGA, Elemental analysis and nitrogen sorption analysis). In addition, eight MOF materials [MIL-101(Cr), ED-g-MIL-101(Cr), TEPA-g-MIL-101(Cr), MIL-101(Cr)-NH2, MIL-101(Al)-NH2, UiO-66(Zr), UiO-66-NH2 and UiO-66(COOH)2] were successfully synthesized. They were chosen due to having high surface areas and large porosity. These MOF compounds were characterized using PXRD, SEM, TGA, and low pressure N2.Successful PIM-1/MOF MMMs were fabricated utilising PIM-1 and the MOFs outlined above with various loadings. The highest MOF loading achieved was 28.6 wt. %, apart from MIL-101(Cr)-NH2, for which it was 23.1 wt. %, and MIL-101(Al)-NH2, for which it was 19.8 wt. %. The morphology of MMMs was characterized by scanning electron microscopy (SEM), proving the dispersion of MOF fillers. Novel PIM-1 supported MOF membranes were successfully prepared by depositing ZIF-8 and HKUST-1 layers on the surfaces of unmodified and modified PIM-1 membranes. These materials were characterized using PXRD, SEM, ATR-IR and SEM-EDX. Gas permeation properties of the MOF/PIM-1 MMMs and PIM-1 supported MOF membranes were determined using a time lag method. Most MMMs tested showed an increase in the permeability and stable selectivity as the MOF amount was increased. However, this was not true for MIL-101(Al)-NH2, where the permeability and selectivity decreased. In contrast, PIM-1 supported ZIF-8 and HKUST-1 membranes caused a sharp decrease in the permeability and increase in the selectivity.
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Mutti, Marcello. "Crystal engineering of mixed-ligand metal-organic frameworks based on simple carboxylate and bipyridyl ligands." Master's thesis, University of Cape Town, 2018. http://hdl.handle.net/11427/29726.
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Over the last few decades research in supramolecular chemistry and crystal engineering have seen an exponential growth. The synthesis of metal-organic frameworks (MOFs) has attracted much interest worldwide due to the possibility of obtaining a large variety of structures with a wide range of applications in fields pertaining to storage, separation and catalysis. This work focuses on the crystal engineering of MOFs based on mixed ligands which may ultimately be used in the gas storage of pollutants, greenhouse gases or fuel. Two novel 2D mixed-ligand MOFs, both based on manganese, 4,4’-bipyridine and 1,3,5- benzenetricarboxylic acid, have been prepared and fully characterized. The employment of dimethylformamide or dimethylacetamide, as the solvent, results in two isostructural MOFs. Another novel MOF, similar in structure to the previous two, with 5-nitroisophthalic acid instead of 1,3,5-benzenetricarboxylic acid has been also prepared and characterized. This MOF has the same metal and ligand combination as, and is largely isostructural to, a literature example, but differs in method of preparation and solvent content. These Mnbased MOFs have potential voids in the structure making them candidates for gas sorption experiments. A novel 2D mixed-ligand MOF based on cobalt, 4,4’-bipyridine and 5-nitroisophthalic acid has been synthesized and fully characterized. Its structure is the same of another MOF, based on manganese, present in this work and like its manganese analogue it exhibits potential void spaces in the framework that make it a candidate for gas sorption experiments. Finally, a novel 2D MOF based on 1,3,5-benzenetricarboxylic acid and cadmium bromide has been synthesized and fully characterized. Dehydration and rehydration studies performed by combining powder X-ray diffraction with thermogravimetric analysis show that it can lose coordinated water, that comes from the reaction solvent, upon heating, and reabsorb water from the atmosphere, ultimately regaining its original structure. All MOFs were synthesized via the solvothermal method and characterized with X-ray diffraction (single crystal and powder) and thermal analyses (hot stage microscopy, differential scanning calorimetry and thermogravimetric analysis).
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Adams, Ryan Thomas. "High molecular sieve loading mixed matrix membranes for gas separations." Diss., Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/39470.
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Traditional gas separation technologies are thermally-driven and can have adverse environmental and economic impacts. Gas separation membrane processes are not thermally-driven and have low capital and operational costs which make them attractive alternatives to traditional technologies. Polymers are easily processed into large, defect-free membrane modules which have made polymeric membranes the industrial standard; however, polymers show separation efficiency-productivity trade-offs and are often not thermally or chemically robust. Molecular sieves, such as zeolites, have gas separation properties that exceed polymeric materials and are more thermally and chemically robust. Unfortunately, formation of large, defect-free molecular sieve membranes is not economically feasible. Mixed matrix membranes (MMMs) combine the ease of processing polymeric materials with the superior transport properties of molecular sieves by dispersing molecular sieve particles in polymer matrices to enhance the performance of the polymers.
MMMs with high molecular sieve loadings were made using polyvinyl acetate (PVAc) and various molecular sieves. Successful formation of these MMMs required substantial modifications to low loading MMM formation techniques. The gas separation properties of these MMMs show significant improvements over PVAc properties, especially for high pressure mixed carbon dioxide-methane feeds that are of great industrial relevance.
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Motegi, Hirofumi. "Synthesis and Characterization of Crystalline Coordination Networks Constructed From Neutral Imidazole Containing Ligand and Rigid Aromatic Carboxylate." Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/77201.
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The work is focused on the investigation of synthesis and structure of crystalline coordination networks by combining first a row transition metal ion with one anionic and one neutral bridging ligand. In the field of crystalline coordination networks, the goal is to synthesize porous 3D crystalline coordination networks with molecular sized cavities. The materials are characterized by XRD and TGA. It is important to understand the structural topologies to develop practical applications, such as gas storage, gas separation, and catalysis.
The bi- and tetra- dentate flexible imidazole ligands, 9,10-bis(imidazol-1-ylmethyl)anthracene (Chapter 2) and 1, 2, 4, 5-tetrakis(imidazol-1ylmethyl)benzene (Chapter 3), are synthesized and used as linkers to construct 1D, 2D, and 3D crystalline coordination networks with cobalt(II) or zinc(II) cations and H3BTC anions under solvothermal conditions.
Two 1D chain networks, [M(HBTC²⁻)(C₂₂H₁₈N₄)(H₂O)₂]•H₂O, are constructed from M(Zn(II) or Co(II)), H₃BTC, and 9,10-bis(imidazol-1-ylmethyl)anthracene (Compound 2.1 and 2.2). These two 1D zigzag chains are linked into infinite 2D sheets by inter-chain π•••π stacking and hydrogen bonding. ⁺
Two 2D and one 3D cobalt(II) coordination networks are constructed from the tetradentate imidazole ligand and H3BTC. Compound 3.1 has a 2D corrugated sheet structure that is linked by inter-layer π•••π stacking and hydrogen bonding. Compound 3.2 has a 2D sheet structure. These sheets are interconnected by hydrogen bonds at the free acid group of the HBTC²⁻ ligand. Compound 3.3 forms a two fold interpenetrated 3D network structure. Void spaces in the structure are filled with six water molecules.
Six 3D cobalt (II) coordination networks are constructed with bidentate rigid imidazole containing neutral ligands, 1,4-bis(imidazol-1-yl)benzene(L1), 1,4-bis(imidazol-1-yl)naphthalene(L2), and 9,10-bis(imidazol-1-yl)anthracene(L3), and H₂BDC or H₃BTC anion (Chapter 4). In 4.1-4.3, L1-L3 affects on degree of interpenetrations constructed with H₂BDC ligand. In 4.1 and 4.2 are interpenetrating 3D networks with no accessible void space. In 4.3, void spaces of 3D networks are filled with 2D sheets. Compounds 4.4-4.6 are prepared by different concentrations of starting materials and different solvents. In 4.4-4.6, L3 serves as a pillar building block to construct 3D networks by applying with H₃BTC ligand. The solvent exchange experiment for 4.4 is further discussed.Ph. D.
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Bushell, Alexandra. "Mixed matrix membranes of a polymer of intrinsic microporosity with crystalline porous solids." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/mixed-matrix-membranes-of-a-polymer-of-intrinsic-microporosity-with-crystalline-porous-solids(6166d350-d969-49bc-8108-1c9afcaaa2f9).html.
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This work explores the fabrication and permeability testing of mixed matrix membranes (MMM) utilising a polymer of intrinsic microporosity (PIM-1) and various fillers. PIM-1 has been chosen for this work due to its high apparent surface area and high sorption of gases. PIM-1 also is a good candidate for gas sorption applications due to the film forming properties of the polymer. The fillers utilised in this work are Metal Organic Frameworks (MOFs) and organic cages, which have been chosen due to the gas sorption properties they exhibit. The MOFs used are micro and nanoparticles of Zeolitic Imidazole Framework-8 (ZIF-8), copper based MOF HKUST-1 and chromium based MOF MIL-101. Micro particles of magnesium based MOF Mg-MOF-74 were also looked at as well as cage 3, nano cage 3 and reduced cage 3. Comparable surface areas of the MOFs compared to those quoted in the literature have been obtained. Successful PIM-1/Filler MMMs were synthesised utilising PIM-1 and the fillers outlined above with various loadings of filler. The highest loading achieved was with a 10:6.4 PIM-1/nanoZIF-8 ratio. All MMMs apart from PIM-1/Mg-MOF-74 MMM were homogenous on a macroscale with scanning electron microscopy proving the dispersion of fillers. Gas transport properties of the MMMs were determined using predominantly a time lag method. PIM-1/ZIF-8 MMMs were also tested using a chromatographic method and using a gas sorption experiment. A range of gases were tested including CO2, N2, CH4, O2, He and H2. Ideal selectivities were also calculated with focus on the gas pairs O2/N2, CO2/CH4 and CO2/N2.When comparing the two permeability methods using the PIM-1/nanoZIF-8 MMM, lower permeability results were found from the time lag method. This was concluded to be due to the aging effect brought about by the vacuum used in the time lag method. The chromatographic method produced positive results with high selectivities, breaking Robeson’s upper bound, for the gas pair O2/N2. All other fillers tested showed an increase in permeability and stable selectivity with an increase in the amount of filler. MIL-101 and Cage 3 were the most successful fillers with high permeabilities of 35600 and 37400 Barrer respectively, encroaching on that of PTMSP. Mg-MOF-74 and reduced cage 3 MMM however, had a detrimental effect on the permeability. Aging data was also investigated which showed that for the majority of MMM the permeability followed the trend of PIM-1. microHKUST-1 and cage 3 of 10:3 loading were shown to give promising results with 10000 and 14300 Barrer respectively compared to 7200 Barrer for PIM-1. Although a loss in permeability is seen, it is still above that of PIM-1 at the same point of aging. These results give a positive indication that MMMs have the potential to provide resistance against aging, a major problem in using high free volume polymers in industrial applications.
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Kozachuk, Olesia [Verfasser], Roland A. [Gutachter] Fischer, and Martin [Gutachter] Muhler. "Advanced functional materials based on metal-organic frameworks : elaboration of redox-active & mixed-component "defekt engineered" MOFs / Olesia Kozachuk ; Gutachter: Roland A. Fischer, Martin Muhler ; Fakultät für Chemie und Biochemie." Bochum : Ruhr-Universität Bochum, 2014. http://d-nb.info/1231542330/34.
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Yildiz, Ceylan [Verfasser], and W. [Akademischer Betreuer] Kleist. "Post-synthetic modification of mixed-linker metal-organic frameworks for the design of heterogeneous single-site catalyst materials and their application in liquid phase oxidation reactions / Ceylan Yildiz ; Betreuer: W. Kleist." Karlsruhe : KIT-Bibliothek, 2020. http://d-nb.info/1209199149/34.
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Jackson, Patricia A. "Mixed-metal organometallic clusters." Thesis, University of Cambridge, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304280.
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Yadnum, Sudarat. "Tailoring complex heterogeneous metal-organic framework structures." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0299/document.
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Dans cette thèse, de nouvelles stratégies pour la préparation de matériaux de type Metal-Organic-Frameworks (MOF) ont été étudiés et développés. L’électrodeposition bipolaire indirecte (IBED) a été utilisé pour préparer ZIF-8 et HKUST-1 sur des substrats métalliques de façon simple et avec une sélectivité spatiale. Ce concept devrait pouvoir être généralisée pour la synthèse de nombreux autres composés MOF, permettant ainsi une synthèse pas chère et verte, conduisant à de nouvelles générations de composites de type Janus basés sur des MOFs. En outre, des électrodes avec une structure hiérarchique macro-/ microporeux de HKUST-1 ont été préparées par une technique de dissolution-dépôt électrochimique. L'approche de synthèse mis au point est très pratique en ce qui concerne la durée des expériences, et ouvre diverses applications pour les MOFs. Enfin des nanoparticules de métaux nobles sur un substrat à base de MIL-101 ont été préparées comme la dernière partie de l'étude expérimentale par dépôt colloïdal. Ce concept peut être généralisé pour la synthèse d'autres composites nanoparticules métalliques / MOF, et pourrait améliorer l'activité catalytique des MOFs. En dehors de l'étude expérimentale, afin de comprendre mieux la catalyse de matériaux MOF, le comportement catalytique de Cu (II) dans le MOF-505 a été théoriquement étudié pour la réaction d'aldolisation Mukayiama par la théorie de densité fonctionnelle et comparé à celui d'un autre catalyseur, Cu-ZSM-5. En outre, le comportement catalytique d'amas homo- et hétéro-bimétalliques, qui sont des complexes métalliques qui représentent les agrégats métalliques dans les MOFs, a également été étudié théoriquement pour la réaction de cycloaddition de dioxyde de carbone et des oxydes d'éthylèneIn this thesis, new strategies for the preparation of Metal 0rganic Frameworks (MOF) materials with designed structures were studied and developed. Indirect bipolar electrodeposition (IBED) was used to prepare ZIF-8 and HKUST-1 on metal substrates in a straightforward and site-selective way. This concept is expected to be able to be generalized for the synthesis of many other MOF compounds, thus allowing a cheap and green synthesis, leading to new generations of MOF-based Janus-type composites. Furthermore, rationally designed hierarchical macro-/microporous HKUST-1 electrodes were prepared via an electrochemical dissolution-deposition technique. The developed synthesis approach is very practical in terms of the time consumption, and opens up MOFs for various applications. Finally, MIL-101-supported noble metal nanoparticles were prepared as the last part of the experimental studies via a simple colloidal deposition technique. This concept might be generalized for the synthesis of other metal nanoparticle/MOF composites, and might improve the catalytic activity of MOFs. Apart from the experimental study, in order to gain a deeper insight into the catalysis of MOF materials, the catalytic behavior of Cu(II) in the paddle-wheel unit of MOF-505 was theoretically investigated for the Mukaiyama aldol reaction via the density functional theory and compared to that of another catalyst, Cu-ZSM-5 zeolite. Besides, the catalytic behavior of homo-metallic clusters and hetero-bimetallic clusters, that are the metal complexes representing the metal clusters in MOFs, were also theoretically investigated for the cycloaddition reaction of carbon dioxide and ethylene oxides
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Srour, Rafif K. "Metal-surface reactions in mixed aqueous organic solvents." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3582.
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Thesis (Ph. D.)--West Virginia University, 2004.Title from document title page. Document formatted into pages; contains xix, 140 p. : ill. Includes abstract. Includes bibliographical references (p. 133-140).
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Veitch, Charles D. "The preparation of polycrystalline mixed-metal oxide phases from metal-organic precursors." Thesis, Glasgow Caledonian University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335019.
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Yan, Yong. "Metal-organic polyhedral framework materials for hydrogen storage." Thesis, University of Nottingham, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.555387.
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This thesis describes the design, synthesis and characterisation of a series of novel metal-organic frameworks constructed from Cu(II) paddlewheels and polydentate aromatic carboxylate ligands. Gas sorption applications of these porous materials have been studied, with an emphasis on hydrogen storage. The effects of cage wall functionalisation within the frameworks, internal BET surface areas and pore volumes, and open Cu(II) sites on H2 adsorption by these materials are investigated. Chapter 1 introduces the current status of H2 storage in metal-organic framework materials. Extended metal-organic structures exhibiting large surface areas and high total pore volumes are favourable for H2 storage at high pressures and cryogenic temperatures. The strategy of utilising metal-organic polyhedra as secondary building blocks in the assembly of highly porous frameworks with high structural stability is discussed. Chapter 2 describes the synthesis of a highly porous (3,24)-connected metal-organic polyhedral framework (denoted NOTT-112) constructed from a nanosized hexacarboxylate linker and {CU2(COO)4} paddlewheels. The framework of NOT- 112 is composed of three types of metal-organic polyhedral cages: cuboctahedra, truncated tetrahedra and truncated octahedra. Desolvated NOTT-112 shows a very large apparent surface area of 3800 m2 g-l (BET) and high H2 storage capacity of 7.07 wt% (excess) at 35 bar at 77 K (total H2 uptake of 10.0 wt% at 77 bar and 77 K), making it one of the best materials for H2 storage at cryogenic temperatures and high pressures. In Chapter 3, neutron powder diffraction (NPD) studies on D2 (deuterium)-loaded NOTT-1l2 give the insight into the mechanism of H2 adsorption in this polyhedral MOF with coordinatively unsaturated Cu(II) sites. NPD experiments reveal that the exposed Cu(II) sites within the smallest cuboctahedral cages in NOTT-112 are the first and strongest binding sites for D2 in this material giving an overall discrimination between the two types of exposed Cu(II) sites within one {CU2} paddlewheel unit. Thus, NPD studies provide, for the first time, direct structural evidence demonstrating that a specific geometrical arrangement of exposed Cu(II) sites, in this case within a [Cu24(isophthalate)24] cuboctahedral cage, strengthens the interactions between D2 molecules and open metal sites. In the second part of this chapter, partially deuterated MOF NOTT-112-d13 was synthesised for inelastic neutron scattering experiments. In Chapter 4, four isostructural metal-organic polyhedral cage based frameworks (denoted NOTT-l13, NOTT-114, NOTT-115 and NOTT-118) with (3,24)-connected topology have been synthesised by combining hexacarboxylate isophthalate linkers with {CU2(COO)4} paddlewheels. All four frameworks have the same cub octahedral cage structure constructed from 24 isophthalates from the ligands and 12 {CU2(COO)4} paddlewheel moieties. The frameworks differ only in the functionality of the central core of the hexacarboxylate ligands with phenyl, trimethylphenyl, phenyl amine and triphenylamine moieties in NOTT-118, NOTT-113, NOTT-114 and NOTT-115, respectively. The desolvated framework materials shows high BET surface areas of 3265, 2970, 3424 and 3394 m2 g-l for NOTT-118, NOTT-l13, NOTT-114 and NOTT-115, respectively. Desolvated NOTT-l13 and NOTT-114 show high total H2 adsorption capacities of 6.7 wt% and 6.8 wt% at 77 K and 60 bar, respectively. Desolvated NO TT -118 and NOTT -115 have significantly higher total H2 uptakes of 8.0 wt% and 7.5 wt% under the same conditions, respectively. Analysis of the heats of adsorption (QsD for H2 reveals that with a triphenylamine moiety in the cage wall, desolvated NOTT-115 shows the highest value of Qs/ for these four materials indicating that functionalisation of the cage walls with more aromatic rings can enhance the H2/framework interactions. In contrast, measurement of Qs/ reveals that the amine substituted tris-alkynylbenzene core used in NOTT-114 gives a notably lower H2/framework binding energy. NOTT-112 to NOTT-115 also show high CH4 adsorption capacities (104-124 cm\STP) cm -3) at 20 bar and room temperature. The amine-functionalised NOTT-114 exhibits strong CO2-framework interaction and high CO2 storage capacity of 22.9 mmol g-1 at 20 bar and 298 K. Chapter 5 describes the linker expansion strategy used in construction of highly porous MOFs. Ultrahigh porosity can be achieved by expansion of the C3-symmetric hexacarboxylate linkers in the polyhedral frameworks. Two isostructural noninterpenetrated (3,24)-connected frameworks NOTT-116 and NOTT-119 have been synthesised based on elongated poly-aromatic hexacarboxylate linkers. Both frameworks of NO TT -116 and NOTT -119 consist of mesoporous cages with diameters up to ~ 3 nm. These two mesoporous materials show good thermal stability and can be fully desolvated without framework collapse by traditional activation method (heating the samples under vacuum). Desolvated NOTT -116 exhibits a significantly high BET surface area (4664 m2 g-I) and a high H2 adsorption capacity (saturated excess H2 uptake of 6.4 wt% at 77 K; total uptake of 9.2 wt% at 77 K and 50 bar). NO TT -119 shows a lower specific surface area of 4118 m2 g -I and a lower saturated excess H2 uptake of 5.6 wt% at 77 K, but a larger pore volume of 2.32 cm3 g-l, leading to a high total H2 uptake capacity of 9.2 wt% at 77 K and 60 bar. Another Cu(II) based MOF NOTT-120 constructed from a hexacarboxylate linker as large as 3.0 nm shows ultrahigh porosity with ultrahigh total pore volume of 2.81 cm3 g-l. Chapter 6 summarizes the H2 storage properties of the (3,24)-connected frameworks and draws an overall conclusions from this study.
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Hu, Moqing. "Design, synthesis and Applications of Metal Organic Framework." Digital WPI, 2011. https://digitalcommons.wpi.edu/etd-theses/964.
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"Porous materials have been a focus of researchers for their applications as molecular storage, molecular sensing, catalysis, asymmetric synthesis and host materials. Metal-organic frameworks (MOFs) represent a promising new class of porous crystalline solids because they exhibit large pore volumes, high surface areas, permanent porosity, high thermal stability, and feature open channels with tunable dimensions and topology. We are currently investigating the design, synthesis, and structures of a new family of MOFs derived from transition metals complexes of 4-(imidazole-1-yl)benzoic acids. Here we present our effort in continuing design and synthesis MOFs composed of 4-(imidazole-1-yl)benzoic acids to expand our knowledge about 4-(imidazole-1-yl)benzoic acid MOF family. A series of ligands are synthesized and Cu MOF-3N, 4, 5 and Cd MOF-3 were synthesized, structure determination found out metal-ligand complex follows our proposal, while Cu MOF-4,5 exhibit porous framework structure via absolute structure determination. Sorption behavior is a key focus in MOF application because the great potential applications MOF bears. Here we carry out a fundamental study about MOF texture and selectivity on MOF-5 and Cd MOF-2. Non-polar polyaromatic hydrocarbons such as naphthalene, phenanthrene, and pyrene, polar molecules such as 2-naphthol, ibuprofen were selected to test our hypothesis that sorption is influenced by the degree of tight fitting, and guest-host interaction such as van der waals and hydrogen bonding. By determining Langmuir isotherms of selected guest molecules, we are able to demonstrate our hypothesis that tighter the fit of the guest molecule and the pores, the higher the amount it would sorb. The sorption difference of non-polar and polar molecules suggest hydrogen bonding is not involved in guest sorption and the dominating force of sorption is hydrophobic interaction. Polymorphism is an interesting phenomenon that bears great value in pharmaceutical industry. Here we report the first case for MOF to serve as a heterogeneous surface that induced nucleation of indomethacin. It is also a first report of this polymorph form of indomethacin. PXRD, DSC, TGA, NMR are conducted as our initial investigation effort. This polymorph exhibits exceptionally thermal stability and low solubility, indicating an unusual tight binding between indomethacin and ethanol solvate. "
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Schneemann, Andreas, Volodymyr Bon, Inke Schwedler, Irena Senkovska, Stefan Kaskel, and Roland A. Fischer. "Flexible metal–organic frameworks." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-149990.
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Advances in flexible and functional metal–organic frameworks (MOFs), also called soft porous crystals, are reviewed by covering the literature of the five years period 2009–2013 with reference to the early pertinent work since the late 1990s. Flexible MOFs combine the crystalline order of the underlying coordination network with cooperative structural transformability. These materials can respond to physical and chemical stimuli of various kinds in a tunable fashion by molecular design, which does not exist for other known solid-state materials. Among the fascinating properties are so-called breathing and swelling phenomena as a function of host–guest interactions. Phase transitions are triggered by guest adsorption/desorption, photochemical, thermal, and mechanical stimuli. Other important flexible properties of MOFs, such as linker rotation and sub-net sliding, which are not necessarily accompanied by crystallographic phase transitions, are briefly mentioned as well. Emphasis is given on reviewing the recent progress in application of in situ characterization techniques and the results of theoretical approaches to characterize and understand the breathing mechanisms and phase transitions. The flexible MOF systems, which are discussed, are categorized by the type of metal-nodes involved and how their coordination chemistry with the linker molecules controls the framework dynamics. Aspects of tailoring the flexible and responsive properties by the mixed component solid-solution concept are included, and as well examples of possible applications of flexible metal–organic frameworks for separation, catalysis, sensing, and biomedicine.
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Stults, Katrina A. "Metal-organic framework-metal oxide composites for toxic gas adsorption and sensing." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/51836.
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Metal organic frameworks (MOFs) and metal oxide-MOF composites were investigated for adsorption and oxidation of carbon monoxide. Metal oxides were successfully included in MOFs via both impregnation and encapsulation. UiO-66, a zirconium-based MOF, was impregnated with magnesium or cobalt oxide. Cobalt oxide in UiO-66 increases the room temperature CO capacity and shows increased adsorption at 65°C due to strong cobalt-CO interactions. Titania and magnetic nanoparticles were encapsulated in HKUST-1, a copper-based MOF. Including titania in HKUST-1 lowers the CO oxidation onset temperature by over 100°C compared with HKUST-1, and the composite reaches complete conversion by 250°C. HKUST-1 with magnetic nanoparticles shows enhanced structural stability and increased room temperature adsorption of CO and hexane. MOF-74, an isostructural family with coordinatively unsaturated metal centers of cobalt, magnesium, nickel, or zinc, was investigated for the metal center’s impact on stability and adsorption. Pre-treatment conditions to optimize accessibility were found that maximize solvent removal while retaining structural integrity. The impact of air exposure on equilibrium CO capacity was investigated, and these predictions were compared to dynamic conditions, separating CO from nitrogen or air at room temperature. The cobalt analog loses only 25% of its CO capacity with air exposure, retaining higher capacity than the other analogs under ideal conditions. Unlike cobalt, the magnesium analog does not follow the predicted trends with air exposure, having higher dynamic capacities with pre-exposed samples. Under all dynamic conditions, the nickel analog oxidized a portion of the carbon monoxide feed.
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Cessford, Naomi Faye. "Simulation of the synthesis of metal-organic framework materials." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/17610.
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The objective of this work was to develop a molecular simulation method with the capacity to represent the synthesis of metal-organic framework (MOF) structures to the extent of being able to accurately predict the MOF structures that form under specified reaction conditions. MOFs are a class of porous, crystalline solids composed of metal-ion vertices coordinated by organic linker molecules. MOFs are created in a self-assembly process in which the building blocks (reactants) retain their integrity. Under different experimental synthesis conditions, a particular combination of building blocks can react to form differing MOF structures. The structure of MOFs confers a large degree of tunability, allowing almost limitless potential for the materials to be designed with the capacity to fulfil the requirements of a specific application. Consequently, MOFs have shown promise for a variety of applications including gas storage, separation and catalysis. Thus, the ability to accurately predict the MOF formed by specifying reaction parameters such as temperature, pH and the concentrations of reactants has great potential because, upon identification of a promising hypothetical structure for a particular application, the synthesis conditions ascertained via the simulation method could be used as the basis for the determination of an experimental synthesis procedure. In addition, a simulation method with the capacity to predict MOF structures affords the opportunity to gain a fundamental understanding of the influence of the experimental synthesis conditions on the structures formed, so as to enable progress towards the rational design of MOFs. In this work, the experimental synthesis of MOFs via self-assembly is modelled using a kinetic Monte Carlo approach. Ideally, simulation of the self-assembly of the building blocks would be modelled atomistically with all atoms in the reactant and solvent molecules represented explicitly. However, due to the prohibitive computational requirements of such a simulation, in this work a “potential-of-mean-force” (PMF) approach was used to represent the solvent implicitly by encompassing the solvent-mediated behaviour in the interactions between building blocks, thereby reducing the computational cost. The PMF approach to the implicit representation of the solvent involved the utilisation of effective pairwise interactions between the constituents of the reactant species. Following extensive testing to ensure that the explicit-solvent behaviour of the reactants could be replicated using the PMF method, this approach allowed computationally efficient implicit-solvent simulations of the synthesis of MOF materials to be performed. Thorough assessment of a method developed to simulate the synthesis of MOFs required investigation of a system which, under different reaction conditions, forms differing structures. In this respect, the cobalt succinates represent an unparalleled test because under different reaction temperatures, reactant concentrations, pH and reaction time, seven different phases have been identified. Furthermore, the parameters within which the different phases form have been clearly delineated experimentally. The method developed has been employed, under the appropriate reaction conditions, to simulate the synthesis of two of the seven identified phases of the cobalt succinates. Whilst still subject to computational limitations, the MOF-synthesis simulation method yields structures characteristic of those expected experimentally under corresponding reaction conditions.
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Moh, Pak Yan. "Crystal growth of the metal-organic framework ZIF-8." Thesis, University of Manchester, 2012. https://www.research.manchester.ac.uk/portal/en/theses/crystal-growth-of-the-metalorganic-framework-zif8(03e7bf63-dc66-48f7-9786-86b98caaf6eb).html.
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The crystal growth of nanoporous materials is different from most other classes of material in that their framework architectures contain periodic arrangement of pores or voids in which there is no direct bonding between adjacent units of the framework. This poses a variety of questions as to how such parts of framework develop during the crystallization process, atomistically and energetically. Here we use the nanoporous metal-organic framework, ZIF-8 as a prototypical material to obtain a basic understanding of the growth of a nanoporous material. The crystals of ZIF-8 produced in the N,N-dimethylformamide solvent [ZIF-8(DMF)] and methanol-co-N,N-dimethylformamide solvent [ZIF-8(MeOH)] are both rhombic dodecahedron in shape with a much smaller crystal size in the latter. In the study of the kinetics of ZIF-8(DMF) crystallization, we get a good agreement in the values of activation energies using both Avrami-Erofe’ev-Hancock-Sharp and Gualtieri’s models, i.e. about 120 kJ mol-1 for nucleation, and 95 kJ mol-1 for crystal growth process. The study of kinetics of ZIF-8 surface growth, by in situ AFM, with ZIF-8(DMF) as seed crystal that are grown in the methanolic growth solution we see faster rate in the <100> directions than the <110> directions, with the most probable activation energy of about 80 kJ mol-1 in both directions. This is the first example of in situ AFM being used to obtain activation energy for a surface growth in MOF. We also reveal here that growth process of ZIF-8 occurs through the nucleation and spreading of successive metastable unenclosed sub-steps to eventually form stable terrace steps of the enclosed framework structure in which this process is reliant on the presence of nonframework species to connect the framework species that have voids between them. The experiments also enable identification of some of the fundamental units in the growth process and the stable crystal surface plane. Further, the spreading of terraces at high supersaturation condition (early state) is fairly isotropic as is seen through the formation of almost-rounded terraces on the surface of ZIF-8. The growth direction becomes clear as the supersaturation condition nears to equilibrium (later stage) by the formation of rhombohedral terraces with pointy ends growing along the <100>, and <110> directions and straight edges growing perpendicular to the <111> direction. Formation of this rhombohedral morphology is explained by a coarse grain approach similar to that used in the Kossel model by making assumptions that the sodalite cage is the growth unit and attachment of one sodalite cage in each growth direction is the rate determining step for the formation of a new row of sodalite cages in each direction. Finally, based on the profiles of growth spirals formed from screw dislocations on the ZIF-8 surface obtained from the ex situ AFM images and ICE theory, plausible screw dislocations with Burgers’ vector of 1/2 <111> and <100>, but not <110>, are deduced. Some of the findings in this work will be applicable to numerous nanoporous materials, and the work in general will support efforts to synthesize and design new framework materials and to control the crystal properties of these materials.
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Trieu, Thuong X. "Syntheses and Characterizations of New Metal-Organic Framework Materials." Thesis, California State University, Long Beach, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10973986.
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Metal–organic frameworks are a rapidly expanding family of crystalline porous materials and have shown great promise to address various challenges such as gas storage and separation due to their well-defined pore size and unprecedented tunability in both composition and pore geometry. Here, we have synthesized and structurally characterized a number of new metal- organic framework materials and studied the effects of ligands and metal types on the construction and properties of metal–organic frameworks. To probe the effects of functional groups on ligands, two zinc-based three-dimensional frameworks have been synthesized. They consist of zinc-triazolate layers pillared by dicarboxylates with different functional groups. In addition, a very unusual magnesium metal-organic framework material has been made. It consists of novel magnesium acetate chains crosslinked by 1,4-benzenedicarboxylate into a three-dimensional framework with large channels. The phase purity and structures of these materials have been determined by powder and single-crystal X-ray diffraction. Their thermal stability and sorption a properties for gas molecules such as N 2, H2, and CO2 have also been studied.
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Campbell, James. "The development of hybrid polymer-metal organic framework membranes for organic solvent nanofiltration." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/33219.
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The most common membranes used for organic solvent nanofiltration (OSN) are integrally skinned asymmetric membranes formed via the immersion precipitation phase inversion process. These membranes are flexible, durable and easy to produce. However control of the porous properties of these membranes is not possible on a molecular level. Integrally skinned asymmetric membranes always exhibit signs of a pore size distribution, which leads to rejections not being optimum. Metal organic frameworks (MOFs) were added to polymeric OSN membranes in an attempt to improve the control over porous properties and separation properties above those achievable using integrally skinned asymmetric polymer membranes. MOFs are crystalline materials with regular porous structures. MOFs have been used for gas separation purposes. This thesis describes the fabrication of hybrid polymer/MOF membranes for OSN applications. MMM fabrication is the tradition approach to create a hybrid polymer/MOF membrane, and contains discrete particles of MOF in a continuous polymer phase. The advantage of MMMs is that they are easy to produce; however, due to the discrete nature of the MOF in the membrane; the permeation of molecules through the membrane is not completely controlled by the MOF. MMMs were shown to have little difference in performance to polymer nanofiltration membranes for OSN. In order for the MOF to exhibit more control over the permeation properties of membranes, in-situ growth (ISG) membranes were developed, whereby MOF material is grown within the pre-existing pores of polymer membranes. Using the MOF HKUST-1 and ultrafiltration polyimide supports ISG membranes were produced and were shown to outperform MMMs in terms of both solute retention and flux decline. Energy-dispersive X-ray spectroscopy (EDX) was used to reveal the distribution of HKUST-1 throughout ISG membranes, which was found to be even across the surface and throughout the cross-section, showing that a continuous phase of MOF had been grown.
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Gao, Min. "Carbon dioxide absorption in metal organic frameworks." Thesis, Queen Mary, University of London, 2015. http://qmro.qmul.ac.uk/xmlui/handle/123456789/23195.
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With the emission of carbon dioxide (CO2) becoming an international worry due its role in climate change, solutions such as CO2 capture and storage technologies are needed to decrease the emissions. The main proportion of CO2 gas emissions is from fossil fuel combustion in a range of industries, including power generation. To develop the CO2 capture system for these operations, new materials are needed for CO2 capture. Metal-organic framework (MOF) materials have porous crystal structures containing organic molecules (organic ligands) linked to each other by metalcontaining nodes. The large internal surface area can be exploited for the adsorption of small gas molecules, and for this reason MOFs may be ideal candidate materials for CO2 capture and gas separations. Thousands of MOF materials have been reported, with different combinations of the ligands and metals and with the capability of forming many different network topologies. Experimentally it is very difficult to study the gas absorption dynamics, interaction and gas adsorption capacity for the large number of materials. This problem can be solved by simulations. The aim of the thesis is to develop a systematic simulation method to screen the MOF properties and CO2 adsorption capacity and interaction dynamics at different environment. The molecular dynamics (MD) method with parameterised force fields was used to study the interactions between CO2 molecules and one class of the MOFs, zeolitic imidizolate frameworks (ZIFs) with zinc as the metal cation. To develop the model, the atom charges have been developed by using the distributed multipole analysis (DMA) method based on ab initio DFT calculations for molecules and clusters. The intermolecular forces were developed by fitting against the MP2 calculations of small clusters of the metal cations and molecular ligands. In order to evaluate the models I simulated the gas-liquid coexistence curve of CO2 and showed that it is consistent with experiments. I also simulated the pure ZIF structures on changing both temperature and pressure, demonstrating the stabilities of the structures but also showing the existence of displacive phase transitions. I have used this approach to successfully study CO2 absorption in a number of ZIFs (from ZIF-zni, ZIF-2, ZIF-4, ZIF-8 and ZIF-10) using MD. The gas absorption capacity and dynamics have been investigated under 25 bar and 30 bar, 200 , showing a promising uptake of CO2. The results have shown that CO2 capacity is mainly determined by the pore sizes and pore surfaces, in which a higher capacity is associated with a higher pore surface. The intermolecular distance of CO2 inside the pores and channels have been investigated in the saturation state. It has been shown that the distance is approximately 4 Å. The attraction force is from the interaction between CO2 and the imidazolate ligands. In addition, the systematic studies of the saturated ZIF system gave the minimum diameters for CO2 adsorption which is approximately 4.4 Å. This interaction has caused the gate opening effects, with the imidazolate ligands being pushed to be parallel to the CO2 molecules and opening up to allow more gas molecules go through the channels that connect the pore structures. This gate opening effect also explains the phase transition in ZIF-10 caused by CO2 molecules in our simulation, and can be applied to predict phase transitions in other materials with similar structure such as ZIF-7 and ZIF-8. The dynamics have also shown that the gas diffusion velocity is determined by the pore structure as well and by the accumulated layers of CO2 on the surface prior to being pushed in toward the centre of the material layer by layer. The de-absorption processes have also been studied in these materials by decreasing the pressure from 25 bar to 1 bar under at same temperature. The results indicate that the de-absorption is a reverse process of absorption. The structure of ZIF-10 went through a phase transition induced by CO2 recovered after the guest molecules had been released. The de-absorption can be accelerated by increasing the temperature.
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Marsden, C. "The synthesis and reactivity of di- and polynuclear mixed metal complexes." Thesis, University of Bristol, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.356224.
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Shoaee, Maryam. "Crystal growth and properties of a copper metal organic framework." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.489541.
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The work presented in this thesis, aims to investigate the growth mechanism of the metal organic framework (MOP), HKUST-1, during the nucleation and the crystal growth periods. This was attempted in two stages, first detailed ex-situ and in-situ studies of the said MOP using atomic force microscopy (APM), followed by the in-situ investigation of the speciation processes in HKUST-1 utilising mass spectrometry (MS) and electron spin resonance (ESR).
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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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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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Padmanaban, Mohan, Philipp Müller, Christian Lieder, Kristina Gedrich, Ronny Grünker, Volodymyr Bon, Irena Senkovska, et al. "Application of a chiral metal–organic framework in enantioselective separation." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-138682.
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A modular approach for the synthesis of highly ordered porous and chiral auxiliary (Evans auxiliary) decorated metal–organic frameworks is developed. Our synthesis strategy, which uses known porous structures as model materials for incorporation of chirality via linker modification, can provide access to a wide range of porous materials suitable for enantioselective separation and catalysis. Chiral analogues of UMCM-1 have been synthesized and investigated for the enantioseparation of chiral compounds in the liquid phase and first promising results are reportedDieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich
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Grünker, Ronny, Volodymyr Bon, Philipp Müller, Ulrich Stoeck, Simon Krause, Uwe Mueller, Irena Senkovska, and Stefan Kaskel. "A new metal–organic framework with ultra-high surface area." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-149154.
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A new mesoporous MOF, Zn4O(bpdc)(btctb)4/3 (DUT-32), containing linear ditopic (bpdc2−; 4,4′-biphenylenedicarboxylic acid) and tritopic (btctb3−; 4,4′,4′′-[benzene-1,3,5-triyltris(carbonylimino)]tris-benzoate) linkers, was synthesised. The highly porous solid has a total pore volume of 3.16 cm3 g−1 and a specific BET surface area of 6411 m2 g−1, adding this compound to the top ten porous materials with the highest BET surface area.
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Worrall, Stephen. "Anodic deposition of metal-organic framework coatings for electrochemical applications." Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/anodic-deposition-of-metalorganic-framework-coatings-for-electrochemical-applications(89a9a8b8-161d-428c-896c-4d0acbb72f4c).html.
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The electrochemical growth of metal-organic framework (MOF) coatings, utilising the anodic dissolution method, has been investigated as a means of preparing MOF coated electrodes for various electrochemical applications. A mechanistic understanding of the formation of the electrode coatings has been further developed. This understanding has been utilised to expand the scope of this technique; to allow for the electrochemical formation of Zn and Co zeoliticimidazolate framework (ZIF) coatings which was hitherto not believed to bepossible. Electrodes coated with Co and Zn ZIFs via this methodology were assessed for their capacitive behaviour and the Co ZIFs exhibited the highest, pure MOF areal capacitance values reported to date. This was attributed to the method of coating formation, which provides well adhered coatings of MOF particles integrated into the electrode surface providing a good electrical connection between the coating and the electrode. Incorporation of GO, via electrophoretic deposition during the coating growth, is shown to improve this capacitance still further. Thecorresponding Zn ZIFs exhibited resistances orders of magnitude higher than their Co analogues; modelling can explain this behaviour with the Co analogue of a given ZIF calculated to have a greater metal contribution to its LUMO leading to a more delocalised electronic structure. Electrodes coated with the Cu MOF HKUST-1 have enabled for the first time the use of MOFs as a template for the electrodeposition of anisotropic metal nanostructures. Such MOF encapsulated metal nanostructures are demonstrated to have applications in surface enhanced Raman spectroscopy (SERS). In addition the same MOF has been discovered to display a redox based hysteresis which allows for the rewritable storage of small amounts of electrically accessible data.
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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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Padmanaban, Mohan, Philipp Müller, Christian Lieder, Kristina Gedrich, Ronny Grünker, Volodymyr Bon, Irena Senkovska, et al. "Application of a chiral metal–organic framework in enantioselective separation." Royal Society of Chemistry, 2011. https://tud.qucosa.de/id/qucosa%3A27771.
Full textAbstract:
A modular approach for the synthesis of highly ordered porous and chiral auxiliary (Evans auxiliary) decorated metal–organic frameworks is developed. Our synthesis strategy, which uses known porous structures as model materials for incorporation of chirality via linker modification, can provide access to a wide range of porous materials suitable for enantioselective separation and catalysis. Chiral analogues of UMCM-1 have been synthesized and investigated for the enantioseparation of chiral compounds in the liquid phase and first promising results are reported.Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.
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Li, Dongfang. "Copper-based Metal-Organic-Framework for Electrochemical Carbon Dioxide Reduction." Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/29915.
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Copper has generated variable studies and applications in electrochemical CO2 reduction reaction (CO2RR) due to its difference in product diversity compared with other transition metals. Metal-Organic Frameworks (MOFs) as high-porosity structures have huge potential in many fields, such as energy storage and conversion, UiO-67 is widely used, especially in scenarios where thermal stability and alkaline environments are required. Here this project will induct Cu@UiO-67 and Cu@UiO-bpy could be electrochemical catalysts for CO2RR under alkaline conditions. It investigated the factor of reacting with different copper sources and their reaction durations, and the components of these two-catalyst ink were considered as variables to be studied. Post-synthesis method was employed to construct the guest-encapsulated MOF structure. At the optimum mass ratio of Cu@UiO-67/Cu@UiO-bpy: carbon black 4:1 the Faradaic efficiency of C2+ products were 53.35% and 65.12%, respectively, which was achieved under a large current density of 500 mA/cm2 in the flow cell.
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Lin, Shaoyang. "Functionalized Metal-Organic Frameworks for Water Oxidation Catalysis." Diss., Virginia Tech, 2019. http://hdl.handle.net/10919/99907.
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Increasing energy demand will not only aggravate global warming, but also cause fossil fuels shortage in the near future. Solar energy is an infinite green energy resource that can potentially satisfy our energy usage. By utilizing solar energy to drive reactions like water splitting, solar fuels system are able to produce valuable energy resource. Catalysts for water oxidation are the essential component of water splitting cells which have been intensively studied. As a solid state porous crystalline material with synthetic tunability, Metal-organic framework (MOF) is a promising platform for water oxidation catalysis due to its outstanding properties. Herein, we aimed to develop molecular catalysts incorporated MOF for water oxidation and study the reaction mechanism.
Chapter 1 introduces the background of water oxidation and previous research on ruthenium nuclear water oxidation catalysts (WOCs). The reaction mechanism of binuclear and mononuclear ruthenium WOCs was briefly summarized. Opportunities for the design and the synthesis of MOF based WOCs were then discussed. Lastly, studies about MOF based WOCs were categorized based on the difference of the WOCs active site location in frameworks.
Water oxidation catalyst [Ru(dcbpy)(tpy)OH2]2+ (RuTB) was incorporated into UiO-67 MOF (resulting materials denoted as RuTB-UiO-67) for chemical water oxidation in Chapter 2. Differences of catalytic reaction behavior between homogeneous RuTB and RuTB incorporated in MOF were examined. Based on MOF particle size dependent catalysis reaction experiments, in-MOF reactivity was anticipated to be primarily arose from redox hopping between RuTB active sites in the framework.
In Chapter 3, RuTB-UiO-67 MOF thin films grown on conducting FTO substrate (RuTB-UiO-67/FTO) were synthesized to test their catalytic activity of electrochemical water oxidation. Electrochemical behavior of RuTB-UiO-67/FTO was found to be consistent with homogeneous RuTB by various electrochemistry study and in-situ X-ray absorption spectroscopy characterization. Scan-rate-dependent voltammetry study demonstrated the homogeneous distribution of electrochemical active sites throughout the MOF thin film. Diffusion controlled redox hopping was attributed to be the main charge transfer pathway during catalysis.
In order to pursue photo-induced water splitting system, we further our study by investigating MOF based photoelectrochemical catalysis in Chapter 4. Photoelectrochemical alcohol oxidation was chosen as the preliminary-stage study towards the more challenging goal, photoelectrochemical water oxidation. Electron transfer processes of the photosensitizer ([Ru(bpy)2(dcbpy)]2+) and the catalyst (RuTB) doped UiO-67 MOF were investigated with transient absorption spectroscopy analysis.
Finally, the role of redox hopping in electrocatalysis by MOF was reviewed in Chapter 5. Pathways of charge transfer in electroactive MOF were first summarized. Redox hopping in MOF was then compared with previous studies on redox active polymer thin films. Lastly, factors that will affect the rate of redox hopping of MOF electrocatalyst were discussed.Doctor of Philosophy
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Ding, Bowen. "Localised Charge Transfer in Metal-Organic Frameworks for Catalysis." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/19852.
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In natural photosynthetic systems localised charge transfer (CT) interactions are employed to prolong photoexcited charge separated states, facilitating conversion to chemical energy. This thesis explores localised CT in redox-active Metal-Organic Frameworks (MOFs) for applications in electrocatalysis and photoelectrocatalysis. Two design strategies are adopted, the first of which incorporates cofacial dimeric units of the photo- and redox-active N,Nʹ-di(4-pyridyl)-1,4,5,8-naphthalenediimide (DPNDI) ligand into a Cd(II) MOF. Crystallographic characterisation of the structural flexibility in this MOF was achieved and linked to an enhanced capability for the MOF to stabilise photoexcited and radical states through localised Intervalence CT interactions. The ability of the material to stabilise the NDI photoexcited radical monoanion state (redox potential -2.1 V vs. SCE) was capitalised on to reduce a discrete organometallic Re(I) based CO2 electrocatalyst to its catalytically active form. Photoelectrocatalytic conversion of CO2 to CO was confirmed at modest reduction potentials of -1.2 V vs. Ag/Ag+. The second approach adopted in this project was the incorporation of the Ni bisdithiolene redox-active unit into a Zn(II) MOF, in the form of the [Ni(pedt)2]- metalloligand (where pedt represents 1-(pyridine-4-yl)ethylene-1,2-dithiolate). The combination of Zn(II) nodes and carboxylate co-ligand coordination resulted in effective electronic isolation of each [Ni(pedt)2]- ligand. The Ni bisdithiolene MOF was successfully applied as a heterogeneous proton reduction electrocatalyst under acidic conditions of 90 mM CH3COOH in 0.1 M [n-Bu4N]PF6/MeCN electrolyte. Tafel analysis of the electrocatalytic behaviour of both the ligand in solution and the MOF demonstrated similarities in catalytic mechanism, evidencing the conservation of molecular electrocatalytic behaviour.
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Ashoka, Sahadevan Suchithra. "Anilate-based molecular building blocks for metal-organic frameworks and molecular conductors Conducting Anilate-Based Mixed-Valence Fe(II)Fe(III) Coordination Polymer: Small-Polaron Hopping Model for Oxalate-Type Fe(II)Fe(III) 2D Networks Nanosheets of Two-Dimensional Neutral Coordination Polymers Based on Near-Infrared-Emitting Lanthanides and a Chlorocyananilate Ligand." Thesis, Angers, 2019. http://bu.univ-angers.fr/Contact.
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Ce travail porte sur la synthèse et la caractérisation de matériaux moléculaires fonctionnels basés sur la molécule anilate et présentant des propriétés de conductivité, de magnétisme et de luminescence. Les anilates sont des dérivés de la 2,5-dihydroxy-1,4-benzoquinone substitués en positions 3 et 6 par une variété d’éléments (H, F, Cl, Br, I, CN, etc). Parmi eux, le seul composé hétérosubstitué ClCNAn2- a été choisi pour préparer une nouvelle famille de polymères de coordination bidimensionnels (PC 2D) avec des métaux de transition ou des ions lanthanides : i) un PC à valence mixte FeIIFeIII, de formule [TAG][FeIIFeIII(ClCNAn)3], contient pour la première fois le cation triaminoguanidinium dans un réseau de coordination.ii) Des PC basés sur le ligand ClCNAn2- et des ions lanthanides émettant dans le proche infrarouge (YbIII, NdIII, ErIII). Ces composés ont été exfoliés en monocouches, et des études de photoluminescence ont été menées à la fois sur les cristaux et les monocouches. iii) Une famille de PC hétéroleptiques basés sur des ions lanthanides et sur deux types de ligands pontants, le ligand ClCNAn2- et des ligands de type carboxylates (DOBDC et F4-BDC). iv) Une famille de PC basés sur des ions DyIII ont été préparés afin d’étudier leur propriétés magnétiques. v) Finalement, la capacité des ligands anilates à se combiner à des conducteurs moléculaires basés sur le BEDT-TTF a été démontrée à travers la synthèse et l’électrocristallisation de semiconducteurs organiques et de conducteurs magnétiques hybrides avec l’anion [Fe(ClCNAn)3]3-This work reports on the design, synthesis and characterization of novel anilate-based functional molecular materials showing luminescent, magnetic and/or conducting properties. The family of anilate ligands comprises several derivatives obtained by introducing various substituents (H, F, Cl, Br, I, CN, etc.) at the 3 and 6 positions of the common 2,5-dihydroxy-1,4-benzoquinone framework. Among the anilate ligands, the only known heterosubstituted anilate with Cl/CN substituents at the 3,6 positions, ClCNAn2-, have been selected for preparing a novel family of 2D layered coordination polymers (2D CP) with both 3d metal ions and 4f lanthanide ions, through a general and straightforward synthetic strategy. i) Mixed-valence FeIIFeIII 2D CP, formulated as [TAG][FeIIFeIII(ClCNAn)3], containing, the tris(amino)-guanidinium (TAG) cation for the first time in such 2D networks has been synthesized and thoroughly characterized. ii) 2D CPs based on NIR-emitting lanthanides (YbIII, NdIII, ErIII) and the ClCNAn2- ligand, have been prepared and characterized. These layered compounds were exfoliated to nanosheets, by sonication-assisted solution synthesis. Time-resolved photoluminescence studies performed on both the bulk and nanosheets are also highlighted. iii) Novel family of heteroleptic 2D CPs based on NIR-emitting lanthanides and mixed ligands (ClCNAn2- and carboxylate ligands (DOBDC and F4-BDC)), were prepared and characterized. vi) Novel family of 2D CPs based on DyIII and ClCNAn2- were prepared in order to investigate their magnetic properties. v) Furthermore, the ability of anilate ligands to work as components of BEDT-TTF- based molecular conductors have been demonstrated through the synthesis, via electrocrystallization technique. vi) П-d hybrid multifunctional paramagnetic molecular conductors BEDT-TTF and [Fe(ClCNAn)3]3-) were also studied
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Ferrandon, Magali. "Mixed metal oxide - noble metal catalysts for total oxidation of volatile organic compounds and carbon monoxide." Doctoral thesis, Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3156.
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Renouf, Catherine Louise. "Coordinatively unsaturated metal organic frameworks for olefin separations." Thesis, University of St Andrews, 2013. http://hdl.handle.net/10023/3686.
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The research presented in this thesis aims to assess the capacity of metal organic frameworks with open metal sites for the separation of olefin mixtures. Chapter 1 provides a background to the field, including industrial separation techniques, metal organic frameworks and their applications and the current state-of-the- art for olefin separation. Chapter 3 describes the experimental techniques used in this research. Ethylene and propylene adsorption and desorption isotherms on Ni-CPO-27 and HKUST-1 at a range of temperatures are presented and compared in Chapter 4, and used to calculate isosteric heats of adsorption at varying coverages using the virial method. These pure component isotherms are used in Chapter 5 to predict selectivities for the separation of binary mixtures using ideal adsorbed solution theory. Temperature programmed desorption is used in Chapter 5 to calculate the enthalpy of desorption using Redhead's method and the heating rate variation method, and the two results are compared. The results presented in Chapters 4 and 5 conclude that propylene/ethylene separation is possible using adsorption onto metal organic frameworks with open metal sites. A new in situ environmental gas cell for single crystal X-ray diffraction is developed in Chapter 6, and the challenges encountered during this development process are discussed. The dehydration of one framework, Co-CPO-27, is studied in detail using the environmental gas cell. A dehydrated structure of HKUST-1, obtained using the gas cell, is presented for the first time. Crystal structures for the complete dehydration-adsorption-delivery cycle for biologically active NO on Co-CPO-27 are presented in Chapter 7, showing the utility of the in situ gas cell for prolonged experiments in multiple different gaseous environments. The crystal structure of NO-loaded Co-CPO-27 improves upon the models suggested in the literature, and the treatment of the dual occupancy of the open metal sites by water and NO is discussed in depth. A crystal structure of CO-loaded Co-CPO-27 is obtained for the first time, and crystal structures of Co-CPO-27 in ethylene and propylene environments are presented.
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Keskin, Seda. "Accelerating development of metal organic framework membranes using atomically detailed simulations." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31679.
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Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2010.Committee Chair: Sholl, David S.; Committee Member: Chance, Ronald R.; Committee Member: Jang, Seung Soon; Committee Member: Koros, William J.; Committee Member: Nair, Sankar. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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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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Putkham, Apipong. "Synthesis, characterisation and gas absorption studies for metal organic framework materials." Thesis, University of Newcastle Upon Tyne, 2010. http://hdl.handle.net/10443/909.
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Recently, porous metal organic framework materials (MOFs) have attracted considerable attention due to the wide range of possible applications of the materials in 1) gas storage, purification and separation; 2) as catalysts and catalyst supports; and 3) for adsorption of environmentally unfriendly species. This study has involved the synthesis, characterisation and determination of the adsorption/desorption characteristics of functionalised porous metal organic framework materials. The overall objective was to increase understanding of the role of surface functional groups and framework flexibility in determining the adsorption characteristics of gases and vapours and assess the possible applications of these materials for gas storage and separation. Adsorption of hydrogen, nitrogen, oxygen and argon were studied in order to investigate the possible applications of metal organic framework NEW-1 in gas storage and air separation. In case of the air separation, adsorption characteristics of O2, N2, and Ar on metal organic framework NEW-1, mixed-zinc/copper organic framework (M’MOF-1) and a carbon based molecular sieve (CMS-40) were compared. The crucial factors such as molecular size and shape in relation to pore structure in determining the adsorption characteristics on materials were investigated. Selected kinetic models i.e. stretched exponential model (SE), double stretched exponential model (DSE) were used to determine the kinetic adsorption parameters. Also, the isosteric enthalpies of gases adsorption at zero surface coverage were determined. The results show that very narrow pores are required in metal organic frameworks to achieve kinetic selectivity similar to CMS-40.
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Bendiksen, Bård A., Eddy W. Hansen, and Harald Walderhaug. "NMR studies of benzene mobility in metal-organic framework UiO-67." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-182918.
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Sua, Andy. "Using Metal-Organic Framework Film as a Drug-Eluting Stent Coating." Thesis, California State University, Long Beach, 2019. http://pqdtopen.proquest.com/#viewpdf?dispub=10975741.
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Metal-organic frameworks have a wide range of applications including gas separation, gas capture, catalysis and drug delivery. Due to the in-stent thrombosis of the current drug-eluting stents we propose replacing the toxic polymer with a more biodegradable MOF thin film consisting of MIL-88b. The MIL-88b thin film was formed on functionalized gold through a direct crystallization method and was confirmed using x-ray diffraction (XRD) and Fourier- transform infrared spectroscopy (FTIR). Possible ibuprofen encapsulation and elution was confirmed through FTIR and UV-VIS spectroscopy. The MIL-88b thin film was also formed on medical grade stainless steel to mimic conditions of the current DES. The surface area, using N2 gas isotherm at 770K, of MIL-88b and MIL-53 was compared to validate the favorable porosity for drug delivery application.
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Martin, Kathleen E. (Kathleen Ewing). "Selective ethylene dimerization by a nickel-exchanged metal-organic framework catalyst." Thesis, Massachusetts Institute of Technology, 2016. http://hdl.handle.net/1721.1/107570.
Full textAbstract:
Thesis: S.M., Massachusetts Institute of Technology, Department of Chemistry, 2016.Cataloged from PDF version of thesis. Vita.
Includes bibliographical references (pages 31-32).
Short linear [alpha]-olefins such as 1-butene are valuable commodity chemicals due to their use as comonomers in linear low-density polyethylene. Presently only homogeneous systems are used to catalyze ethylene dimerization in industry, causing many to suffer from quick deactivation and poor selectivity. The metal-organic framework (MOF) CPF-5 Mn₅(TBA)₃(HCOO)₃(OH)(H₂O₂)2]]₄·6DMF where TBA = 4-(l H-tetrazol-5-yl)benzoic acid provides an ideal structural template for the development of a heterogeneous catalyst for ethylene dimerization. Ni exchanged CPF-5 (Ni-CPF-5) treated with diethylaluminum chloride had a maximum turnover frequency of 23,000 mole ethylene per mole Ni per hour, and a maximum selectivity for 1-butene of 80% under optimized conditions. Ethylene pressure strongly influenced the activity and selectivity of Ni-CPF-5. Though the observed activity behavior is similar, the selectivity trends diverged significantly from previously reported MOF dimerization catalysts.
by Kathleen E. Martin.
S.M.
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Munn, Alexis S. "Synthesis and characterisation of metal-organic framework materials with carboxylate ligands." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/58606/.
Full textAbstract:
The adsorption of various guest molecules by the flexible 1,4-benzenedicarboxylate metal-organic framework (MOF), MIL-53, has been followed using in situ diffraction techniques. This crystalline MOF displays a structural expansion upon the adsorption of guest molecules, evident by a change in unit cell parameters, which allows adsorption to be followed using diffraction techniques. Adsorption studies were performed with the Fe(III) form of MIL-53 using both liquidand gas-phase guest molecules. The results from in situ X-ray diffraction (XRD) studies show that small aliphatic-alcohols give rise to a two-step expansion whereas branchedalcohols and larger aromatic molecules result in only a one-step expansion. The solvent used for liquid phase studies was shown to affect guest adsorption; benzothiophene and benzothiazole were adsorbed more quickly from a solution of heptane than from a solution of isopropanol. Gas phase studies were used to investigate the effect of occluded water molecules inside the pores of the framework upon the adsorption of methanol. A combination of XRD, thermogravimetry and inelastic neutron scattering studies were used to show that methanol does not displace water when hydrated MIL- 53(Fe) is used as an adsorbent. Two equivalents of methanol can be packed inside the pores of the framework, irrespective of the adsorbent being hydrated or dehydrated. Eight linker-modified MIL-53(Al) materials were supplied by research partners and in situ XRD studies were performed to reveal the effect of the modifications upon the adsorption of gas-phase molecules. The results show that the linkers change the behaviour of the material towards certain guest molecules and the most dramatic effect was seen when the benzene ring of the linker was replaced by cyclohexane. A series of cobalt (II) MOFs synthesised with carboxylate and pyridine-N-oxide linkers is presented. The effect of functionalising the pyridine ring upon the topology of the resulting framework was studied. Resonance and steric effects were found to influence the structure of the final product. One of the new materials has the potential to be used as an adsorbent due to a 3D porous structure.
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Bendiksen, Bård A., Eddy W. Hansen, and Harald Walderhaug. "NMR studies of benzene mobility in metal-organic framework UiO-67." Diffusion fundamentals 20 (2013) 43, S. 1, 2013. https://ul.qucosa.de/id/qucosa%3A13612.
Full text