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Simancas, Coloma Jorge. "Synthesis and Characterization of Zeolitic Materials Using Phosphorous Organic Structure Directing Agents." Doctoral thesis, Universitat Politècnica de València, 2021. http://hdl.handle.net/10251/171267.
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[ES] Las zeolitas son materiales cristalinos microporosos con canales y tamaños de poro de dimensiones moleculares. La estructura y composición de las zeolitas les confiere interesantes propiedades que permiten su aplicación en una amplia gama de aplicaciones industriales como adsorción, separación o catálisis. La síntesis de zeolitas es la etapa más importante para el control de la estructura y composición de las zeolitas y, por tanto, crítica para la optimización de sus propiedades.
Esta tesis se ha centrado en la síntesis de zeolitas utilizando compuestos que contienen fósforo (cationes fosfonio y aminofosfonio) como Agentes Directores de Estructura (P-ADE). El uso de compuestos fosforados influye en la cristalización y propiedades de las zeolitas obtenidas en comparación con las zeolitas obtenidas con cationes de amonio clásicos.
Los compuestos fosforados se eligieron debido a su diferente química y estabilidad con respecto a los cationes de amonio clásicos comúnmente usados en la síntesis de zeolitas. Estos aspectos se estudiaron con un estudio comparativo de diferentes cationes de amonio y fosforados.
Los compuestos de fósforo utilizados en este trabajo han dado lugar a nuevas estructuras cristalinas (ITQ-58 e ITQ-66) y han abierto nuevas vías de síntesis de zeolitas ya conocidas (RTH, IWV y DON), ampliando su gama de composiciones químicas.
La descomposición térmica de los P-ADE confinados dentro de las zeolitas da lugar a la formación de especies de fósforo extra-red que permanecen dentro de los canales y cavidades de las zeolitas. Estas especies modulan las propiedades ácidas y de adsorción de los materiales finales dependiendo de los tratamientos post-síntesis. En este trabajo se ha estudiado una ruta para la incorporación de cantidades controladas de fósforo durante la etapa de síntesis. Esto ha permitido controlar la adsorción y las propiedades ácidas en las zeolitas de poro pequeño, lo que no se puede lograr mediante metodologías de post-síntesis.[CA] Les zeolites són materials cristal·lins microporosos amb canals i mides de porus de dimensions moleculars. L'estructura i composició de les zeolites els confereix interessants propietats que permeten la seua aplicació en una àmplia gamma d'aplicacions industrials com adsorció, separació o catàlisi. La síntesi de zeolites és l'etapa més important per al control de l'estructura i composició de les zeolites i, per tant, crítica per a l'optimització de les seues propietats. Aquesta tesi s'ha centrat en la síntesi de zeolites utilitzant compostos que contenen fòsfor (cations fosfoni i aminofosfoni) com a agents directors d'estructura (P-ADE). L'ús de compostos fosforats influeix en la cristal·lització i propietats de les zeolites obtingudes en comparació amb les zeolites obtingudes amb cations d'amoni clàssics. Els compostos fosforats es van triar a causa de la seua diferent química i estabilitat pel que fa als cations d'amoni clàssics utilitzats en la síntesi de zeolites. Aquests aspectes s¿estudiaren amb un estudi comparatiu de diferents cations d'amoni i fosforats. Els compostos de fòsfor utilitzats en aquest treball han donat lloc a noves estructures cristal·lines (ITQ-58 i ITQ-66) i han obert noves vies de síntesi de zeolites ja conegudes (RTH, IWV i DO), ampliant la seua gamma de composicions químiques. La descomposició tèrmica dels P-ADE atrapats dins de les zeolites dona lloc a la for-mació d'espècies de fòsfor extra-xarxa que romanen dins dels canals i cavitats de les zeolites. Aquestes espècies modulen les propietats àcides i d'adsorció dels materials finals depenent dels tractaments post-síntesi. En aquest treball s'ha estudiat una ruta per la incorporació de quantitats controlades de fòsfor durant l'etapa de síntesi. Això ha permés controlar l'adsorció i les propietats àcides en les zeolites de porus petit, el que no es pot aconseguir mitjançant metodologies de post-síntesi.
[EN] Zeolites are microporous crystalline materials with channels and pore openings of molecular dimensions. The structure and composition of zeolites confers them interesting properties that allow their application in a wide range of industrial applications as adsorption, separation or catalysis. The synthesis of zeolites is the most important stage to control the structure and composition of zeolites, and thus, critical to optimize their properties. This thesis has been focused on the synthesis of zeolites using phosphorous containing compounds (phosphonium and aminophosphonium cations) as Organic Structure Directing Agents (P-OSDA). The use of these phosphorous compounds influence the crystallization and properties of the obtained zeolites compared to zeolites obtained with classical ammo-nium cations. Phosphorous compounds were chosen because of their different chemistry and stabil-ity properties respect to classical ammonium cations commonly used in the synthesis of zeo-lites. These aspects were studied in a comparative study with different ammonium and phosphorous cations. The phosphorous compounds used in this work have yielded new crystalline structures (ITQ-58 and ITQ-66) and opened new routes for the synthesis of already known zeolites (RTH, IWV and DON), widening their chemical composition range. The thermal decomposition of the P-OSDAs entrapped inside the zeolites yields to the formation of extra-framework phosphorus species that remain inside the channels and voids of the zeolites. These species modulate the adsorption and acid properties of the final materials depending on the post-synthesis treatments. In this work, a route for the incorporation of controlled amounts of phosphorus during the synthesis stage has been studied. This has allowed to control the adsorption and acid properties in small pores zeolites, which cannot be achieved by post-synthesis methodologies.
I wish to firstly acknowledge the Spanish Government for the necessary funding for the FPI pre-doctoral fellowship (BES-2013-062999). Also, this thesis would not have been possible without the infrastructures provided by the UPV and the CSIC staff, fused into the ITQ. Furthermore, I want to acknowledge the Microscopy Service of the UPV for their support in sample microscopy characterization
Simancas Coloma, J. (2021). Synthesis and Characterization of Zeolitic Materials Using Phosphorous Organic Structure Directing Agents [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/171267
TESIS
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Wright, P. A. "The structure of zeolites and the zeolite-sorbate complex." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372290.
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Kovo, Abdulsalami Sanni. "Development of zeolites and zeolite membranes from Ahoko Nigerian kaolin." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/development-of-zeolites-and-zeolite-membranes-from-ahoko-nigerian-kaolin(3496e1fa-ece8-4781-be3f-a27a103f4c4a).html.
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Zeolites and zeolite membranes are two important advanced chemical materials which are widely used in chemical processes. The manufacture of these materials usually involves the use of expensive chemicals. This study involves the use of Ahoko Nigerian kaolin (ANK) as precursor material for the development of zeolites and zeolite membranes. The synthesis of zeolite A, Y and ZSM-5 was successfully obtained following a sequence, collection of the raw clay from Nigeria, metakaolinization, dealumination and actual hydrothermal synthesis of the zeolites. Raw ANK was refined using sedimentation technique and about 97% kaolin was recovered from the raw sample. A novel metakaolinization technique was developed to convert kaolin into a reactive metastable phase. Amorphous metakaolin was obtained at a temperature of 600°C and exposure time of 10 min. This is a significant result because previous studies use higher temperatures and longer exposure times for the metakaolinization step. The metakaolin was used to prepare a number of different zeolites under various conditions. Highly crystalline zeolite A was obtained at an ageing time of 12 h, crystallization time of 6 h and crystallization temperature of 100oC. Zeolite Y was obtained at an ageing time of 3 h, crystallization time of 9 h and crystallization temperature of 100oC. Zeolite Y was also synthesised by using a dealuminated kaolin and highly crystallized zeolite Y with Si/Al ratio of 1.56 and BET surface area was obtained of 630 m2/g. ZSM-5 was synthesised using an ageing period of 36 h, crystallization time of 48 h and temperature of 140oC. The results obtained from zeolite powder synthesis from ANK were then used as guide to prepare supported zeolite films and membranes by a hydrothermal method. The effect of the support surface (stainless steel) was investigated using two synthesis methods namely modified in-situ and secondary (seeded) growth. Zeolite A, Y and ZSM-5 films were successfully prepared from ANK for the first time and on two modified supports, etched and oxidised. The zeolite films and membranes developed showed complete coverage on the two supports with the oxidised showing better adhesion and intergrowth. The separation performance of the three developed zeolite membrane was tested by pervaporation of water/ethanol mixture. The results of pervaporation of ethanol/water mixture showed that zeolite A membrane is highly selective towards water mainly because of hydrophilic properties occasioned by the high aluminium content. Zeolite Y membrane show a similar response when their separation performance was evaluated but with less selectivity because of reduced aluminium content. ZSM-5 showed selectivity towards ethanol because of it hydrophobicity allowing only ethanol to permeate. In all the zeolite membranes, the flux is lower in comparison to commercial zeolite membranes due mainly to the thickness of the zeolite layer. Oxidised support membranes showed better performance because of their better interaction between the oxide surface and the aluminosilicate gel. The results show that ANK can successfully be used to prepare zeolites and zeolite membrane.
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Cheung, Ocean. "Narrow-pore zeolites and zeolite-like adsorbents for CO2 separation." Doctoral thesis, Stockholms universitet, Institutionen för material- och miljökemi (MMK), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-101629.
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A range of porous solid adsorbents were synthesised and their ability to separate and capture carbon dioxide (CO2) from gas mixtures was examined. CO2 separation from flue gas – a type of exhaust gas from fossil fuel combustion that consists of CO2 mixed with mainly nitrogen and biogas (consists of CO2 mixed with mainly methane) were explicitly considered. The selected adsorbents were chosen partly due to their narrow pore sizes. Narrow pores can differentiate gas molecules of different sizes via a kinetic separation mechanism: a large gas molecule should find it more difficult to enter a narrow pore. CO2 has the smallest kinetic diameter in zeolites when compared with the other two gases in this study. Narrow pore adsorbents can therefore, show enhanced kinetic selectivity to adsorb CO2 from a gas mixture. The adsorbents tested in this study included mixed cation zeolite A, zeolite ZK-4, a range of aluminophosphates and silicoaluminophosphates, as well as two types of titanium silicates (ETS-4, CTS-1). These adsorbents were compared with one another from different aspects such as CO2 capacity, CO2 selectivity, cyclic performance, working capacity, cost of synthesis, etc. Each of the tested adsorbents has its advantages and disadvantages. Serval phosphates were identified as potentially good CO2 adsorbents, but the high cost of their synthesis must be addressed in order to develop these adsorbents for applications.At the time of the doctoral defence the following papers were unpublished and had a status as follows: Papers 4-8: Manuscripts.
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Belkhair, Sama Salem. "Antimicrobial properties of Ag zeolites and Ag zeolite containing polymers." Thesis, Manchester Metropolitan University, 2016. http://e-space.mmu.ac.uk/617118/.
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Ag zeolites have been studied in this thesis for antibacterial applications in powder form or in composite materials. The influence of the textural characteristics (crystal size and mesoporosity) of silver-exchanged FAU- and BEA-type zeolites on their antimicrobial efficacy was studied. Two pairs of zeolite X and zeolite beta with different sizes as well as a mesoporous zeolite beta were tested against Escherichia coli (E. coli) and Candida albicans (C. albicans). Reduction of crystal size resulted in a slight decrease in the killing efficacy against both microorganisms. Zeolite beta showed higher activity than zeolite X despite the lower Ag content in that sample, which was attributed to the higher concentration of silver released from zeolite beta samples to the medium. Introduction of mesoporosity had a beneficial effect on the antimicrobial efficacy. Cytotoxicity measurements using peripheral blood mononuclear cells indicated that Ag zeolite X was more toxic compared to Ag beta, particularly the nanosized sample. The influence of the form of silver (metallic or ionic) on the antimicrobial efficacy was determined using Ag-loaded EMT zeolites. The killing efficacy of pure EMT, Ag+-EMT and Ag0-EMT against E. coli was studied semi-quantitatively. The antibacterial activity increased with increasing Ag content for both types of samples (Ag+-EMT and Ag0-EMT). The Ag0-EMT samples show slightly enhanced antimicrobial efficacy compared to that of Ag+-EMT, however, the differences are not substantial and the preparation of Ag nanoparticles is not viable considering the complexity of preparation steps. A multidisciplinary approach has been applied to the preparation of antibacterial Ag zeolite/silicone elastomer composites aimed at products that satisfy a range of requirements, namely good mechanical properties after zeolite incorporation and strongly antibacterial. The composites showed strong efficacy against E. coli and Staphylococcus epidermidis (S. epidermidis). Organic functionalisation of the zeolite with organo-silanes prior blending with the matrix usefully improved composite mechanical properties and reduced colour development in Ag zeolite containing silicone elastomers. The same approach was applied for the preparation of dental acrylic resins. Antibacterial dental resin containing Ag zeolites at loadings of 0.2, 0.4, 0.7 and 2 wt.% were prepared. The composites showed strong efficacy against E. coli and no viable E. coli were detected after 5 hours of incubation. The presence of Ag zeolites within the acrylic resin resulted in resin discolouration, which was more pronounced at high Ag zeolite loadings. A sustained Ag release over long periods of time (54 days) was observed with a greater Ag release in artificial saliva compared to that in distilled water. Dental resins loaded with Ag-free zeolites followed by post-fabrication insertion of Ag by ion-exchange were prepared to overcome discolouration. The materials prepared using this approach had a similar colour to that of the original polymer as determined by the colour measurements. These composites showed strong efficacy against E. coli and no viable E. coli cells were detected after 5 hours of incubation.
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Lee, Hyunjoo Davis Mark E. Davis Mark E. "A new strategy for synthesizing zeolites and zeolite-like materials /." Diss., Pasadena, Calif. : California Institute of Technology, 2005. http://resolver.caltech.edu/CaltechETD:etd-05122005-144223.
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Huang, Wei. "Selective hydrogenation on zeolite-supported bimetallic catalysts." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 0.90 Mb., p. 76, 2005. http://proquest.umi.com/pqdlink?did=1037889271&Fmt=7&clientId=8331&RQT=309&VName=PQD.
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Uçar, Şule Yılmaz Selahattin. "Investigation Of Catalytic Activity And Selectivity Of Pd and Ni Loaded Clinoptilolite Rich Natural Zeolite For Citral Hydrogenation/." [s.l.]: [s.n.], 2002. http://library.iyte.edu.tr/tezler/master/kimyamuh/T000122.doc.
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Wang, Bo. "TOWARDS COMMERCIALIZABLE FEATURED ZEOLITES - MESOPOROUS PARTICLES, NANOPARTICLES AND BENDABLE ZEOLITE MEMBRANES." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1478609347266087.
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Lydon, Megan Elizabeth. "Properties of inorganically surface-modified zeolites and zeolite/ polyimide nanocomposite membranes." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49069.
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Mixed matrix membranes (MMMs) consisting of a polymer bulk phase and an inorganic dispersed phase have the potential to provide a more selective membrane because they incorporate the selectivity of a zeolite dispersed phase while maintaining the ease of use of a polymer membrane. A critical problem in MMM applications is control over the polymer-zeolite interface adhesion during fabrication which can detrimentally impact membrane performance. In this work, MgOxHy (1≤x≤2, 0≤y≤2) nanostructures have been grown on pure-silica MFI and aluminosilicate LTA zeolites through four surface deposition techniques: Grignard decomposition reactions, solvothermal and modified solvothermal depositions, and ion-exchange induced surface crystallization. The structural properties of the surface nanostructures produced by each of the four methods were thoroughly characterized for their morphology, crystallinity, porosity, surface area, elemental composition, and these properties were used to predict the method’s suitability for use in composite membranes. The nanostructured zeolites were used in mixed matrix membranes (MMMs) at two MMMs weight loadings. The dispersion, mechanical properties, and CO₂/CH₄ gas separation properties were measured MMMs made with each method of functionalized LTA. All functionalization methods improve adhesion with the polymer observable by microscopy, the dispersion of particles, and the elastic modulus and hardness of the membrane. Gas permeation measurements prove the quality and effectiveness of the Ion Exchange membrane for CO₂/CH₄ separation by its significant increase in selectivity over the pure polymer. Lastly, the interface between the two materials was studied by probing the interfacial polymer mobility using NMR spin-spin relaxation measurements and mechanical mapping of membrane cross sections. It was shown that the nanostructures have both steric and chemical interactions with the polymer. Mapping of the elastic modulus indicated that functionalization methods that resulted in poorer zeolite coverage also disrupted the mechanical properties of the membrane at the interface of the materials. The investigations in this thesis provide detailed structure-property relationships of surface-modified molecular sieves and nanocomposite membranes fabricated using these materials, allowing a rational approach to the design of such materials and membranes.
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Akolekar, D. B. "Sorption, diffusion and catalytic reactions on zeolites and zeolite-like materials." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 1987. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/3287.
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Tosheva, Lubomira. "Zeolite macrostructures." Licentiate thesis, Luleå tekniska universitet, 1999. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-17951.
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The preparation of zeolite macrostructures in the form of bilayered hollow tubes and microspheres is presented. The bilayered hollow ZSM-5/silicalite-1 tubes were prepared using carbon fibers as a substrate. The surface of the fibers was modified and colloidal silicalite-1 seed crystals adsorbed. The fibers were then treated with a synthesis mixture yielding ZSM-5. After separation of the fiber/zeolite composites a second treatment resulting in the crystallization of silicalite-1 was performed. Finally, the carbon fibers were removed by calcination leaving hollow tubes. Silicalite-1 micropsheres were prepared using macroporous anion exchange resins as shape directing macro-templates. Resin beads were hydrothermally treated with a synthesis solution yielding silicalite-1 resulting in the crystallization of silicalite-1 in the pores of the resin. The resin was then removed by calcination leaving self-bonded silicalite-1 micropsheres identical in shape and size to the original resin beads. The zeolite macrostructures were extensively characterized using SEM, XRD, EDS-analysis, Raman spectroscopy, nitrogen adsorption and microhardness measurements.Godkänd; 1999; 20070322 (ysko)
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Lee, Hyunjung. "DESIGN AND PHOTOCHEMICAL STUDIES OF ZEOLITE-BASED ARTIFICIAL PHOTOSYNTHETIC SYSTEMS." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1039117753.
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Gren, Wojciech. "Atomistic simulations of zeolite surfaces and the zeolite-water interfaces : towards an understanding of zeolite growth." Thesis, University of Bath, 2010. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.537774.
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Cornelius, Mero-Lee Ursula. "The role of aluminium content in the control of the morphology of fly ash based hierarchical zeolite X." University of the Western Cape, 2015. http://hdl.handle.net/11394/5232.
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>Magister Scientiae - MScCoal is the main source of electricity in South Africa, the combustion of which produces a large amount of waste (coal fly ash) annually. The large-scale generation of coal fly ash places major strain on landfills and the material is toxic in nature. The high silicon and aluminium content in fly ash makes it a suitable starting material for zeolite synthesis. Utilisation of fly ash as a starting material for zeolite synthesis alleviates an environmental burden by converting a waste product to an industrially applicable material. In this study, hierarchical zeolite X was synthesised from coal fly ash via the fusion method. The clear fused fly ash (FFA) extract (with molar composition 0.12 Al·14.6 Na·1.00 Si·163 H₂O) served as the synthesis solution for hydrothermal treatment. The influence of synthesis parameters (such as Si/Al ratio, aluminium source, hydrothermal temperature and stirring) on hierarchical zeolite X formation was studied to determine the cause behind the formation of this material. Synthesised zeolites and starting materials (Arnot coal fly ash and fused fly ash) were characterised by various analytical techniques such as XRD and SEM-EDS to determine the phase purity, morphology and elemental composition (framework Si/Al ratio) of these materials. The synthesis of hierarchical zeolite X under hydrothermal conditions was found to be highly sensitive to the aluminium content of the synthesis solution. The hierarchical morphology of zeolite X was formed preferentially in relatively aluminium-deficient (i.e. high Si/Al ratio) synthesis environments under stirred hydrothermal conditions of 90 °C for 16 hours. In the case of sodium aluminate addition, octahedral shaped zeolite X crystals were formed in relatively low Si/Al ratio synthesis environments, which was attributed to the presence of excess sodium cation content in the synthesis solution. Selected hierarchical zeolites (D2 and E2) were characterised further to gain more insight into the properties of this material. HR-TEM and FTIR revealed that hierarchical zeolite D2 and E2 exhibited the typical structural features of zeolite X. Zeolite D2 and E2 contained both micropores and mesopores and had a high BET surface area of 338-362 m²/g. These zeolites also exhibited appreciable solid acidity (0.81-1.12 mmol H/g zeolite). These properties make hierarchical zeolite X a favourable material for application in catalysis or adsorption. Overall, the formation of zeolite X with hierarchical morphology was proposed to be linked to the presence of zeolite P1 structural units in the framework of the zeolite.
National Research Foundation
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Boruntea, Cristian-Renato. "Design, synthesis and characterization of small-pore zeolites for industrial environmental applications." Doctoral thesis, Universitat Politècnica de València, 2020. http://hdl.handle.net/10251/141094.
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[ES] El Proyecto de investigación aquí descrito se estructura en dos partes. La primera parte se centra en la investigación fundamental con el objetivo de crear un protocolo para la síntesis de zeolitas. La segunda parte se refiere al diseño, síntesis y caracterización de nuevas zeolitas, particularmente utiles para aplicaciones DeNOx,, pero también podría ser útil para aplicaciones MTO.
La investigación fundamental sugiere un Nuevo modelo de preparación de zeolitas utilizando otras zeolitas como simiente. Este proceso se llama transformación zeolita-zeolita o también conversión interzeolita. El alto rendimiento obtenido, la rápida cristalización y la mejor utilización y rendimiento de los materiales de partida se han tenido en cuenta para mejorar el proceso en base a un proyecto de doctorado financiado por una empresa. Este método se ha ilustrado utilizando varias zeolitas como semilla, entre otras FAU y CHA, para la preparación de las dos zeolitas objetivo: AEI y AFX.
En la segunda parte, la investigación se centra en el diseño de nuevas zeolitas de poro medio. Se han seleccionado tres zeolitas hipotéticas de una base de datos de 933611 estructuras. Esta selección se ha realizado utilizando descriptores específicamente diseñados en base a la aplicabilidad de estas zeolitas en procesos DeNOx zeolitas. A continuación se han buscado los agentes directores de estructura (ADE) más apropiados, con la ayuda de métodos computacionales, algunos de los cuales se han sintetizado posteriormente. El uso de dichos ADE en el gel de síntesis ha permitido la obtención de una zeolita cuya topología (ERI) ha sido identificada mediante análisis por PXRD, y cuya morfología y tamaño de cristal (particularmente pequeño) la hacen muy adecuada para su uso como catalizador en algunos procesos.
El trabajo de síntesis también reveló la aparición de una nueva zeolita de alta densidad, llamada 'paracelsio-K'. Este nuevo material se ha obtenido al explorar el espacio de fases que cristalizan al utilizar 1-methyl-DABCO como ADE. La síntesis de esta zeolita tiene un especial interés porque el ADE no se incorpora en los canales de la zeolita, pero más bien influyendo en la nucleación y cristalización. La caracterización reveló que la composición del material es próxima al mineral microcline, estructuralmente cercano al paracelsio, ambos feldespatos. A diferencia de los feldespatos el paracelsio-K contiene moléculas de agua en su interior (1 molécula por cavidad) y puede describirse como el material más simple de la familia de las zeolitas que contiene cadenas del tipo 'doble-cigüeñal'. Utilizando los elementos topológicos correspondientes a esta estructura es posible generar estructuras zeolíticas ya conocidas, como GIS, APC, MER, PHI, SIV y algunas otras zeolitas hipotéticas.[CAT] El Projecte d'investigació aquí descrit s'estructura en dos parts. La primera part se centra en la investigació fonamental amb l'objectiu de crear un protocol per a la síntesis de zeolites. La segona part es refereix al disseny, síntesis i caracterització de noves zeolites, particularment útils per a aplicacions DeNOx , però també podria ser útil per a aplicacions MTO. La investigació fonamental suggereix un nou model de preparació de zeolites utilitzant altres zeolites com a llavor. Aquest procés s'anomena transformació zeolita-zeolita o també conversió interzeolita. L'alt rendiment obtingut, la ràpida cristal·lització i la millor utilització i rendiment dels materials de partida s'han tingut en compte per millorar el procés en base a un projecte de doctorat finançat per una empresa. Aquest mètode s'ha il·lustrat utilitzant diverses zeolites com a llavor, entre altres FAU i CHA, per a la preparació de les dues zeolites objectiu: AEI i AFX. A la segona part, la investigació se centra en el disseny de noves zeolites de porus mitjà. S'han seleccionat tres zeolites hipotètiques d'una base de dades de 933.611 estructures. Aquesta selecció s'ha realitzat utilitzant descriptors específicament dissenyats sobre la base de l'aplicabilitat d'aquestes zeolites en processos DeNOx zeolites. A continuació s'han buscat els agents directors d'estructura (ADE) més apropiats, amb l'ajuda de mètodes computacionals, alguns dels quals s'han sintetitzat posteriorment. L'ús d'aquests ADE al gel de síntesi ha permès l'obtenció d'una zeolita la topologia (ERI) ha estat identificada mitjançant anàlisi per PXRD, i la morfologia i mida de vidre (particularment petit) la fan molt adequada per al seu ús com a catalitzador en alguns processos. El treball de síntesi també va revelar l'aparició d'una nova zeolita d'alta densitat, anomenada 'paracelsio-K'. Aquest nou material s'ha obtingut a explorar l'espai de fases que cristal·litzen en utilitzar 1-methyl-DABCO com ADE. La síntesi d'aquesta zeolita té un especial interès perquè el ADE no s'incorpora en els canals de la zeolita, però més aviat influint en la nucleació i cristal·lització. La caracterització va revelar que la composició del material és propera al mineral microcline, estructuralment proper al paracelsio, tots dos feldspats. A diferència dels feldspats el paracelsio-K conté molècules d'aigua al seu interior (1 molècula per cavitat) i pot descriure com el material més simple de la família de les zeolites que conté cadenes del tipus 'doble-cigonyal'. Utilitzant els elements topològics corresponents a aquesta estructura és possible generar estructures zeolítiques ja conegudes, com GIS, APC, MER, PHI, SIV i algunes altres zeolites hipotètiques.
[EN] The research project described herein is structured in two parts. The first part is focused on the fundamental research with the aim of creating a toolbox for zeolite preparation. The second part deal with the design, synthesis and characterization of novel zeolites particular useful for DeNOx applications, but could be also useful for MTO applications. The fundamental research is addressing a novel approach of preparing zeolites by using other zeolites as raw materials. This process is known as zeolite-to-zeolite transformation or interzeolite conversion. The high yield obtained, fast crystallization time and the better utilization of the raw materials (e.g. parent zeolite, organic structure directing agent (OSDA)), are important benefits of interzeolite conversion technic, which answer the objectives formulated for an industrial PhD project. The method has been exemplified by using various raw materials as parent zeolites, such as FAU and CHA for the preparation of two target small pore zeolites AEI and AFX. In the second part the focus has been on the design of novel small pore zeolites. Three hypothetical frameworks have been selected by narrowing down a database containing 933611 structures. The selection has been performed by using the general descriptors for the state-of-the-art DeNOx zeolites (e.g. CHA). This was followed by finding suitable OSDAs for the selected frameworks, by using computational methods. The usage of the theoretically predicted OSDAs in synthesis gels made possible the synthesis of a novel high-silica zeolite. PXRD analysis, revealed that the zeolite has the ERI framework topology. The obtained material has a distinct particle morphology and smaller crystallites, which are key parameters for various catalytic processes. The synthesis work revealed also a novel dense zeolite, named K-paracelsian. The new material has been obtained while exploring the phase space using 1-methyl-DABCO as OSDA. The synthesis of this zeolite is especially interesting in the sense that the OSDA is not being incorporated into the zeolite channels, but rather influencing the nucleation and crystallization. Further characterization revealed a material compositionally closely related to the mineral microcline and structurally closely related to the mineral paracelsian, both of which are feldspars. In contrast to the feldspars, K-paracelsian contains intrazeolitic water corresponding to one molecule per cage and can be described as the simplest endmember of a family of dense double-crankshaft zeolite topologies. By applying the identified building principle, a number of known zeolite frameworks (e.g. GIS, APC, MER, PHI, SIV) and hypothetical zeolite topologies can be constructed.
The authors thank Haldor Topsoe A/S and Innovation Fund Denmark for financial support under the Industrial PhD programme (Case no. 1355-0174B). We thank MINECO of Spain for funding (SEV-2016- 0683 and RTI2018-101033-B-100) and ASIC-UPV for the use of computational facilities. We also thank Prof. M. M. J. Treacy for assistance with the Database of Prospective Zeolite Structures.
Boruntea, C. (2020). Design, synthesis and characterization of small-pore zeolites for industrial environmental applications [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/141094
TESIS
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Hawley, Harmonie A. "TCE removal utilizing coupled zeolite sorption and advanced oxidation." Link to electronic thesis, 2003. http://www.wpi.edu/Pubs/ETD/Available/etd-0428103-150434.
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Mosca, Alessandra. "Structured zeolite adsorbents /." Luleå : Luleå University of Technology, 2007. http://epubl.ltu.se/1402-1757/2007/47/LTU-LIC-0747-SE.pdf.
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Campos, Reales Castellanos Jose Eduardo. "Novel zeolite manufacture." Thesis, University of Birmingham, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.422716.
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Wan, Yu Shan Susanna. "Zeolite microstructured reactors." Thesis, University College London (University of London), 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.405836.
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Blair, Johanna Wendy. "Zeolite biomimetic catalysts." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388460.
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Li, Jian-Wei. "Zeolite-modified electrodes /." [S.l.] : [s.n.], 1993. http://www.ub.unibe.ch/content/bibliotheken_sammlungen/sondersammlungen/dissen_bestellformular/index_ger.html.
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Barquist, Karna Nicole Larsen Sarah C. "Synthesis and environmental adsorption applications of functionalized zeolites and iron oxide/zeolite composites." [Iowa City, Iowa] : University of Iowa, 2009. http://ir.uiowa.edu/etd/334.
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Barquist, Karna Nicole. "Synthesis and environmental adsorption applications of functionalized zeolites and iron oxide/zeolite composites." Diss., University of Iowa, 2009. https://ir.uiowa.edu/etd/334.
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Silicalite-1 crystals and hollow tube structures were synthesized and functionalized with amine and sulfur containing groups. The adsorption behavior of metal ions (Pb2+, CrO4-) in aqueous solution was investigated on nanocrystalline zeolites functionalized with amines and thiols. Nanocrystalline zeolites with a diameter of 30-50 nm and external surface areas around 100 m2/g were functionalized with 3-aminopropyltriethoxysilane (3-APTES) and 3-mercaptopropyltrimethoxysilane (3-MPTMS). The materials were characterized by 29Si magic angle spinning nuclear magnetic resonance spectroscopy and x-ray diffraction. The adsorption of metal ions from aqueous solutions of Pb (NO3)2 and Na2Cr2O7 was measured by inductively coupled plasma-atomic emission spectroscopy. The effects of various conditions such as pH and concentration were studied to optimize adsorption. Adsorption on functionalized mesoporous silica (MS) was conducted for comparison to the functionalized zeolites.
Magnetic zeolite/iron composites were prepared using nanoscale and commercial faujasite zeolites. The composites were functionalized with amine groups to facilitate chromate adsorption under acidic conditions. The materials were characterized using nitrogen adsorption, scanning electron microscopy, thermogravametric analysis, FTIR spectroscopy, and Mossbauer spectroscopy. The adsorption of chromium was evaluated using inductively coupled plasma-optical emission spectroscopy (ICP/OES) to monitor solution chromium quantitatively. The removal of the composites with a magnet was demonstrated. The materials were then evaluated for the adsorption of Cr6+ using ICP-OES to detect chromium.
Iron containing zeolite composites were prepared using nanoscale faujasite zeolites. The composites were functionalized with amine groups and Fe ions to facilitate arsenate(As V) adsorption under a variety of pH conditions. The materials were characterized using nitrogen adsorption, X-ray diffraction, thermogravametric analysis and FTIR spectroscopy, and Mossbauer spectroscopy. The adsorption of arsenic was evaluated using inductively coupled plasma-optical emission spectroscopy (ICP/OES) to monitor solution concentration quantitatively. The removal of the composites with a magnet was demonstrated. Kinetics and pH dependence of the adsorption were studied.
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Navlani-García, Miriam. "Preparation of zeolite-based catalysts and zeolite thin films for environmental applications." Doctoral thesis, Universidad de Alicante, 2014. http://hdl.handle.net/10045/46105.
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Zimmermann, Nils E. R., Timm J. Zabel, and Frerich J. Keil. "Transport into zeolite nanosheets." Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-183170.
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Alem, Nassreen. "Zeolite encapsulated metal complexes." Thesis, University of Reading, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239055.
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Yao, Jun. "Zeolite supported platinum electrocatalysts." Thesis, University of Southampton, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.396108.
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Herreros, Bruno. "Silicoglycolates in zeolite synthesis." Thesis, University of Cambridge, 1995. https://www.repository.cam.ac.uk/handle/1810/273044.
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Kassaee, Mohamad Hadi. "Internal surface modification of zeolite MFI particles and membranes for gas separation." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44906.
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Zeolites are a well-known class of crystalline oxide materials with tunable compositions and nanoporous structures, and have been used extensively in catalysis, adsorption, and ion exchange. The zeolite MFI is one of the well-studied zeolites because it has a pore size and structure suitable for separation or chemical conversion of many industrially important molecules. Modification of zeolite structures with organic groups offers a potential new way to change their properties of zeolites, beyond the manipulation of the zeolite framework structure and composition.
The main goals of this thesis research are to study the organic-modification of the MFI pore structure, and to assess the effects of such modification on the adsorption and transport properties of zeolite MFI sorbents and membranes. In this work, the internal pore structure of MFI zeolite particles and membranes has been modified by direct covalent condensation or chemical complexation of different organic molecules with the silanol defect sites existing in the MFI structure. The organic molecules used for pore modification are 1-butanol, 1-hexanol, 3-amino-1-propanol, 1-propaneamine, 1,3-diaminopropane, 2-[(2-aminoethyl)amino]ethanol, and benzenemethanol. TGA/DSC and 13C/29Si NMR characterizations indicated that the functional groups were chemically bound to the zeolite framework, and that the loading was commensurate with the concentration of internal silanol defects. Gas adsorption isotherms of CO2, CH4, and N2 on the modified zeolite materials show a range of properties different from that of the bare MFI zeolite. The MFI/3-amino-1-propanol, MFI/2-[(2-aminoethyl)amino]ethanol, and MFI/benzenemethanol materials showed the largest differences from bare MFI. These properties were qualitatively explained by the known affinity of amino- and hydroxyl groups for CO2, and of the phenyl group for CH4. The combined influence of adsorption and diffusion changes due to modification can be studied by measuring permeation of different gases on modified MFI membranes.
To study these effects, I synthesized MFI membranes with [h0h] out-of-plane orientation on α-alumina supports. The membranes were modified by the same procedures as used for MFI particles and with 1-butanol, 3-amino-1-propanol, 2-[(2-aminoethyl)amino]ethanol, and benzenemethanol. The existence of functional groups in the pores of the zeolite was confirmed by PA-FTIR measurements. Permeation measurements of H2, N2, CO2, CH4, and SF6, were performed at room temperature before and after modification. Permeation of n-butane, and i-butane were measured before and after modification with 1-butanol. For all of the studied gases, gas permeances decreased by 1-2 orders of magnitude compared to bare MFI membranes for modified membranes. This is a strong indication that the organic species in the MFI framework are interacting with or blocking the gas molecule transport through the MFI pores.
A detailed fundamental study of the CO2 adsorption mechanism in modified zeolites is necessary to gain a better understating of the adsorption and permeation behavior of such materials. Towards this end, an in situ FTIR study was performe.For the organic molecules with only one functional group (1-butanol, benzenemethanol, and 1-propaneamine), physical adsorption was found - as intuitively expected - to be the only observed mode of attachment of CO2 to the modified zeolite material. Even in the case of MFI modified with 1,3-diaminopropane, only physical adsorption is seen. This is explained by the isolated nature of the amine groups in the material, due to which only a single amine group can interact with a CO2 molecule. On the other hand, chemisorbed CO2 species are clearly observed on bare MFI, and on MFI modified with 3-amino-1-propanol or 2-[(2-aminoethyl)amino]ethanol. Specifically, these are carbonate-like species that arise from the chemisorption of CO2 to the silanol group in bare MFI and the alcohol groups of the modifying molecule. The possibility of significant contributions from external surface silanol groups in adsorbing CO2 chemisorbed species was ruled out by a comparative examination of the FTIR spectra of 10 μm and 900 nm MFI particles modified with 2-[(2-aminoethyl)amino]ethanol.
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Forner, Ricardo. "Organometalico [MnCp(CO)3] ocluido em zeolito Y." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250383.
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Orientador: Gilson Herbert Magalhães DiasTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Resumo: Esta tese teve como objetivo o estudo dos efeitos estéricos e eletrônicos dos zeólitos faujasita HY, LiY, NaY e CsY na estrutura, reatividade e comportamento térmico do organometálico [MnCp(CO)3]ocluído. As diversas formas alcalinas do zeólito Y foram preparadas por troca iônica no zeólito Na56Y comercial e os estudos das interações, do comportamento térmico e da reatividade do complexo ocluído nos zeólitos foram feitos por espectroscopia de infravermelho com transformada de Fourier (FTIR) em um sistema especialmente construído para essa finalidade. O organometálico [MnCp(CO)3] adsorvido nos zeólitos apresentou, no mínimo, cinco bandas nos espectros FTIR, que foram atribuídas a diferentes sítios de ancoramentos localizados na superfície e na supercavidade. A decomposição do convidado ocluído ocorre com velocidades maiores nos sítios de ancoramento que possuem interações cátion-carbonila mais fracas. Os espectros obtidos para a oclusão do organometálico em zeólitos parcialmente hidratados mostraram que as interações carbonilas-cátions no zeólito parcialmente hidratado são tão intensas quanto às interações do convidado no hospedeiro desidratado. Os cálculos computacionais, que simularam as interações entre o zeólito e o organometálico, forneceram informações sobre energias de interações, comprimentos e ângulos de ligação. Os espectros simulados exibiram bandas de estiramentos de carbonilas próximas às bandas dos espectros obtidos experimentalmente
Abstract: This thesis aimed to study the steric and electronic effects of faujasita zeolites HY, LiY, NaY and CsY on the structure, reactivity and thermal behavior of [MnCp(CO)3] organometallic compound occluded. Various alkaline forms of zeolite Y were prepared by ion exchange in the zeolite Na56Y. Study of the interactions, the thermal behavior and reactivity of the organometallic compound occluded in zeolites were done using FTIR spectroscopy in a system especially constructed for this purpose. The FTIR spectra of [MnCp(CO)3] compound adsorbed in zeolites displays at least 5 bands that were attributed to different anchoring sites located on the surface and in the supercages. The decomposition of the occluded guest was faster in the anchoring sites where the interactions cation-carbonyl were weaker. The occluded organometallic spectra in partially hydrated zeolites have showed the same strength for carbonyl-cation and water-cation interactions. The computational calculations, that have simulated the interactions of the organometallic with zeólito, provided information on interaction energy, lengths and angles of bonds. The simulated spectra have showed carbonyl stretching bands in similar way to experimental spectra
Doutorado
Quimica Inorganica
Doutor em Ciencias Quimicas
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Schmidt, Franz. "Hierarchische nanoporöse Materialien für eine verbesserte katalytische Leistung im MTO-Prozess." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2013. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-114962.
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In dieser Arbeit werden die Ergebnisse mehrerer verschiedener Synthesemöglichkeiten für eine Optimierung der katalytischen Leistung durch Hierarchisierung zweier Molekularsiebe vorgestellt. Dabei wurde der ZSM-5 als Vertreter der Alumosilikate und der SAPO-34 (Silizium Aluminium-phosphat) ausgewählt, da diese als entsprechende MTH-Katalysatoren bereits wirtschaftliche Bedeutung erlangt haben. Die verschiedenen Möglichkeiten, ein solches hierarchisches Netzwerk zu generieren, werden dabei in Bezug auf die katalytische Leistung der jeweiligen Katalysatoren evaluiert und bewertet.
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Murphy, Michael Stephen. "Structural modification of zeolite beta." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq23826.pdf.
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Murphy, Michael Stephen. "Structural modification of zeolite beta." Thesis, University of New Brunswick, 1996. http://hdl.handle.net/1882/511.
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Nicol, Jaqueline Mary. "Vibrational spectroscopy of zeolite complexes." Thesis, Durham University, 1985. http://etheses.dur.ac.uk/6754/.
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Using infrared spectroscopy, studies of the interaction of small molecules {e.g. CO, C(_2)H(_2), CH(_3)CHO) with zeolites have been carried out. The work has resulted in the observation of both stable chemisorbed complexes and reacting species for which time-resolved measurements have been made. The isomerization of cyclopropane on ZnNa-A has been followed using time resolved spectroscopy. From the intensity of the v(C=C) stretch of the product, propene, the kinetics of the reaction have been followed and the reaction sites identified. The rate of isomerization was found to be very much faster than that previously reported for similar systems. In a separate study the adsorbed complex formed between propene and Na-A zeolite has been investigated. On adsorption of carbon monoxide on Cu{I) containing Y zeolite, three different locations for the adsorbed CO have been observed. These experiments have been repeated for a variety of sample pretreatment conditions and the results used to explain the inconsistency in the scientific literature, where a range of v(C=0) stretching frequencies have been pre sented by different authors. In essence, it has been shown that the sample pretreatment has a marked effect on this cation distribution within the zeolite, and hence on the number and intensity of CO bands that are observed, since each site has a characteristic carbonyl stretching frequency. Copper containing Y zeolites were also investigated through the adsorption of ammonia and the reduction of the Cu(II) form by CO and NH(_3). The rationale for this work was to attempt to better understand the reduction process. A study of ethyne adsorbed on ZnNa-A has revealed two adsorption sites within the framework. At one site C(_2)H(_2) was found to be weakly n-bonding to the Na cations. The second site was identified as the Zn cations, at which the C2H2 was observed to lose hydrogen and form Zn-acetylide. The Zn-acetylide was observed to react slowly with zeolitic water to form ethanal. In separate studies ethanal was shown to be formed when C2H2 was adsorbed on Ag-A zeolite but no chemical reaction was observed on the Na-A form. Ethanal adsorbed on some ion-exchanged type A zeolites (Zn, Na, Ag) has been observed to form complexes with the charge compensating cations and framework hydroxyl groups. On zeolite ZnNa-A three species were identified; a hydrogen bonding complex formed with the framework hydroxyl groups, and two coordinating complexes formed with the charge compensating cations; (one with the Na(I) ions and one with the Zn(II) ions).In contrast two complexes were found on Ag-A (one hydrogen bonding, the other with the Ag(^+) cation) and one on Na-A, formed with the Na(I) ions. When adsorbed ethanal was heated, under vacuum, on ZnNa-A and Na-A new species were formed. These were tentatively identified as carboxylate species. A study of ethene adsorbed on ZnNa-A has been made by infrared and inelastic neutron scattering spectroscopy (INS).The IR measurements clearly showed the formation of a TT-bonded adsorption complex, by the observation of the formally inactive V2(C=C) stretching mode of ethene but no v(C-H) stretching vibrations were observed. In the INS data a number of vibrations of the adsorbed C(_2)H(_4) with respect to the surface were seen, as well as a weak broad band due to the v(C-H) stretching modes.
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Sokol, Alexey Abramovich. "Defect structures in zeolite crystals." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326272.
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Mole, Vincent Charles. "Improved zeolite builders for detergents." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/46453.
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Leung, Ka Ming. "Zeolite frameworks with β-cages." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:2e0224c8-b104-4162-966d-a39d50c14f09.
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This study focuses on five zeolites: sodalite, zeolite A, linde type N, zeolite Y, and EMC-2, with SOD, LTA, LTN, FAU, and EMT framework topologies respectively. All of these zeolites have β-cages as the framework building units. The aims are to understand the conditions which control the formation of different zeolite phases and some of the physical properties of zeolite frameworks, mainly the framework exibility, and the capacity of β-cage to accommodate guest molecules such as water and methanol. The hydrothermal and microwave syntheses of zeolite with no organic structure directing agents require precise control of synthesis conditions and form the fundamental part of this study. Reaction temperature and synthesis time control the phase purity in zeolite A synthesis. A transformation from zeolite A to sodalite is observed and is related to framework density and reaction temperatures. Microwave syntheses of sodalite show that the batch compositions and methods of preparation also affect the as-synthesised zeolite phases and a new sodalite morphology is found. By using microwaves instead of traditional hydrothermal methods, one of the most complex zeolites, linde type N zeolite, was synthesised. This is the first study to report this new method. The newly defined extrinsic exibility window is studied on more depth in this work. While the intrinsic exibility is defined by the ability of an empty framework to flex with no distortions in the primary tetrahedral building units; the extrinsic exibility window is limited by the host-guest steric interactions between the framework and the extra framework contents. In zeolite Y, the extrinsic exibility window can be limited not only under compression, but also in expansion, as the β-cage in a maximally expanded framework lack the exibility to adapt to bulky contents such as a combination of methanol and water molecules. It is also found that the β-cage in zeolite Y can only accommodate a maximum number of two water molecules and one methanol molecule. The same phenomenon is observed in sodalite under compression. In the sodium form, the framework remains within its intrinsic exibility window when fluorinert is used as pressure transmitting media, as fluorinert does not enter the zeolite pores. However, an extrinsic exibility window is observed in both the sodium and sodium bromide forms with methanol/ethanol/water mixture as pressure transmitting media. An exception is seen in EMC-2. The intrinsic and extrinsic exibility windows are identical to each other. The presence of 18-crown-6 ether molecules in the pores does not affect the exibility window. The crown ether, despite its steric bulk, does not limit the geometric exibility of the framework since the cage of the EMT framework has enough space to accommodate the crown ether molecule and can adapt to the contraction. This shows that the extrinsic exibility window of zeolite frameworks is controlled not only by the extra framework contents, but also by the framework building units.
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Rode, Edward James. "Rhodium-zeolite hydroformylation of propylene." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/71252.
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The purpose of this research was to characterize the rhodium exchanged NaX and NaY zeolites as propylene hydroformylation catalysts. Catalytic activity was measured in a differential bed reactor. Flow in situ infrared spectroscopy was used to probe the coordination chemistry of the zeolite modified rhodium carbonyls.
The catalytic activity of rhodium zeolites at atmospheric pressure and between 100-150ºC was measured. The rate of n-butyraldehyde production was approximately 5x10⁻³ moles/g-
Rh hr at 150°C. Regioselectivity was dependent upon pretreatment. Precarbonylation with carbon monoxide, drying with air, and heating with N₂ prior to hydroformylation conditions produced a straight to branched isomer ratio (n/i) of 1.9-2.3. Partial reduction with 10% H₂ in N₂ at 127°C lowered n/i to 1.3. Hydrogenation to propane was 3-10 times faster than the hydroformylation rate at 150°C.
Catalytic activity was sensitive to cation exchange conditions. Rhodium form, pH, temperature, and salt concentration altered catalyst behavior. Only RhCl₃•3H₂O preparations on NaY zeolite produced above 80ºC, a pH above 4, and a salt concentration of 0.1N NaCl were required in order to produce an active hydroformylation catalyst. Ammine complexes did not activate under any circumstances.
It was found that the degree of hydration controlled the formation of rhodium carbonyls. On NaY, the hydrated rhodium zeolite reacted with CO at 120ºC to form Rh₆(CO)₁₆. By drying the zeolite in air at 190ºC, two rhodium dicarbonyls, Rh(CO)₂(Oz)₂-NaY and Rh(CO)₂(Oz)(H₂O)-NaY, were formed. The rhodium carbonyls were reacted with n-hexyl diphenylphosphine to determine rhodium locations. Rh(CO)₂(Oz)₂-NaY was located at the surface while the other two species were located within the zeolite cages. One dicarbonyl species, Rh(CO)₂(Oz)₂-NaX, was observed on NaX. It was determined by reactions with phosphines that this species resides in the zeolite cages.
Reaction intermediates identified by FTIR under hydroformylation conditions suggested that the heterogeneous catalyst proceeds through a mechanism similar to that occurring in solution. Heterogeneous reaction orders also agreed with those reported for homogeneous hydroformylations.
Addition of dimethylphenylphosphine (DMP) to the rhodium zeolites significantly increased regioselectivity. Rates were slightly less than those from the unmodified rhodium carbonyls. However, the phosphine modified rhodium zeolites deactivated within 16 hours. Continuous exposure to DMP decreased the rate of deactivation.Ph. D.
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Shieh, Dah-Chung. "Spectroscopic studies of zeolite formation /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu148732358362193.
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Shah, Rashed. "Zeolite-Modified Fischer-Tropsch Synthesis." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/10738.
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The improvement of the gasoline selectivity and quality with the addition of HZSM-5 to the Fe-FT process is evident from literature. The catalytic performance of the combined Fe-FT/HZSM-5 system has been observed to decline with time-on-stream, attributed to the migration of alkali from the Fe-FT catalyst tothe HZSM-5 zeolite. The catalytic performance of the combined Fe-FT/HZSM-5system has, however, been observed to considerably decline with time-on-stream, aphenomenon which has been attributed to the migration of alkali from the Fe-FT catalyst to he HZSM-5 zeolite. The objective of this study is to characterize and confirm the reported performance of the Fe-FT and combined Fe-FT/HZSM-5 catalyst systems in a stirred from top internal recycle reactor under typical high temperature FT conditions.
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Kwan, Siu Ming. "Zeolite-based micro fuel cells /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?CBME%202008%20KWAN.
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Goldyn, Kamila. "Zeolite nanocrystals for biomedical applications." Thesis, Normandie, 2018. http://www.theses.fr/2018NORMC240/document.
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Les propriétés des nanozéolithes, à savoir leur grande surface, leur stabilité hydrothermale et leur nature non toxique, permettent leur utilisation dans des applications prospectives, notamment la biomédecine (capteurs, administration de médicaments et de gaz) et la microbiologie (agents antibactériens). De nombreuses recherches ont été consacrées à l’étude de nouvelles applications biomédicales utilisant des matériaux zéolithiques, toutefois leur plein potentiel n’a toujours pas été pleinement dévoilé.Il est bien connu que la résistance croissante aux traitements établis de tumeurs et d’infections bactériennes par radiothérapie et antibiotiques est un problème de première importance. Par conséquent, le développement de nouvelles stratégies thérapeutiques pour résoudre ces problèmes est très démandé.L'objectif de cette recherche de doctorat est de synthétiser et de modifier post-synthétiquement des zéolithes nanométriques pour des applications biomédicales. Cela implique l'échange d'ions de zéolithe avec divers cations pour trouver celui qui convient le mieux aux applications souhaitées : le traitement antimicrobien, la réoxygénation des tissus tumoraux et l’administration de gaz.Dans cette étude, nous rapportons: (i) l'effet de la zéolithe FAU de type nanométrique modifiée au cuivre sur les bactéries de type ESKAPE (chapitre 3), (ii) l’utilisation de nanozéolithes contenant du métal comme outil d'oxygénation et de visualisation tissulaire (chapitre 4) et enfin (iii) l'utilisation de nanozéolithes FAU comme vecteur de l'oxyde nitrique et du dioxyde de carbone pour prévenir des maladies potentiellement létales (chapitre 5)The properties of nanozeolites, namely, large surface area, hydrothermal stability and non-toxic nature, enable their utilization in forward-looking applications, including biomedicine (sensors, drug and gas delivery) and microbiology (antibacterial agents). Hence, a lot of research has been devoted to study the new biomedical applications using zeolitic materials, their full potential has still not been fully unveiled.It is well recognised that growing resistance to already established treatments of tumors and bacterial infections using radiotherapy and antibiotics is a distressing matter. Therefore, the development of new therapeutic strategies towards above issues is of great demand.The goal of this PhD research is to synthesise and post-synthetically modify nanosized zeolites for biomedical applications. This involves the ion-exchange of zeolite with various cations to find the most suitable one for desired applications in regards to antimicrobial treatment, tumour tissue reoxygenation and gas delivery.In this study, we report: (i) the effect of copper modified nanosized FAU type zeolite on ESKAPE type bacteria (Chapter 3), (ii) the metal containing nanozeolite as a tool for tissue oxygenation and visualisation using MRI (Chapter 4), and lastly (iii) the use of FAU nanozeolite as nitric oxide and carbon dioxide gas vector to prevent life threatening conditions (Chapter 5)
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Bezerra, Diogo Pereira. "ModificaÃÃo do estado da arte de adsorventes para captura de CO2 por incorporaÃÃo de amina e troca-iÃnica." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=12141.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoCO2 à o principal GÃs de Efeito Estufa (GEE), que pode causar consequÃncias indesejÃveis ao meio ambiente, como o aquecimento global. Hà muitas opÃÃes para a separaÃÃo de CO2, entre as quais a adsorÃÃo em materiais porosos à destaque neste trabalho. Carbonos ativados e zeÃlitos tÃm sido propostas como potenciais materiais adsorventes, devido à sua afinidade natural com o CO2 e para a possibilidade de adaptar as propriedades texturais e quÃmica de superfÃcie para aumentar a capacidade e seletividade em cenÃrios de captura especÃficos. Esta tese se concentra em modificar a quÃmica da superfÃcie de adsorventes convencionais, por meio de impregnaÃÃo de amina e troca-iÃnica, de modo a avaliar o efeito de tais modificaÃÃes sobre o seu desempenho de captura de CO2. A secÃÃo experimental foi dividida em trÃs estudos distintos. Inicialmente, isotermas de adsorÃÃo de CO2 foram obtidos em zeÃlito X funcionalizado com concentraÃÃes crescentes de 2-aminoetanol (Monoetanolamina, MEA). Subsequentemente, o carbono ativado, foi investigado como um suporte para a impregnaÃÃo de amina para a captura de CO2. Por Ãltimo, um estudo de troca iÃnica em zeÃlito X foi realizada a fim de investigar a influÃncia de diferentes cÃtions de compensaÃÃo na captura de CO2. Em geral, MEA impregnaÃÃo conduziu a uma deterioraÃÃo nas propriedades texturais dos adsorventes estudados, que sÃo essencialmente microporosos. Quanto maior a concentraÃÃo da soluÃÃo de impregnaÃÃo aumenta, maior à o preenchimento dos microporos por aminas. Hà evidÃncias experimentais de que parte da amina carregada liga covalentemente à estrutura zeolÃtica. A capacidade de adsorÃÃo de CO2 à sempre menor para amostras impregnadas do que para o suporte puro a 298 K, contudo em temperatura maiores, 348 K, à possÃvel observar melhorias. ZeÃlito X mantÃm textura e estrutura cristalina intacta nas amostras de troca-iÃnica. AdsorÃÃo de CO2 à reforÃada por cÃtions de compensaÃÃo menores e mais leves, como LÃtio, atingindo 4,82 mmol/g a 348 K e 1 bar. Em termos de capacidade de trabalho (entre 0,1 e 1 bar) a 298 K, o Ba em zeÃlito X tem um desempenho melhor do que os outros sÃlidos. Ele continua a ser estudado em trabalhos futuros a CO2/N2 e CO2/CH4 seletividade de tais materiais em condiÃÃes secas e Ãmidas.
CO2 à o principal GÃs de Efeito Estufa (GEE), que pode causar consequÃncias indesejÃveis ao meio ambiente, como o aquecimento global. Hà muitas opÃÃes para a separaÃÃo de CO2, entre as quais a adsorÃÃo em materiais porosos à destaque neste trabalho. Carbonos ativados e zeÃlitos tÃm sido propostas como potenciais materiais adsorventes, devido à sua afinidade natural com o CO2 e para a possibilidade de adaptar as propriedades texturais e quÃmica de superfÃcie para aumentar a capacidade e seletividade em cenÃrios de captura especÃficos. Esta tese se concentra em modificar a quÃmica da superfÃcie de adsorventes convencionais, por meio de impregnaÃÃo de amina e troca-iÃnica, de modo a avaliar o efeito de tais modificaÃÃes sobre o seu desempenho de captura de CO2. A secÃÃo experimental foi dividida em trÃs estudos distintos. Inicialmente, isotermas de adsorÃÃo de CO2 foram obtidos em zeÃlito X funcionalizado com concentraÃÃes crescentes de 2-aminoetanol (Monoetanolamina, MEA). Subsequentemente, o carbono ativado, foi investigado como um suporte para a impregnaÃÃo de amina para a captura de CO2. Por Ãltimo, um estudo de troca iÃnica em zeÃlito X foi realizada a fim de investigar a influÃncia de diferentes cÃtions de compensaÃÃo na captura de CO2. Em geral, MEA impregnaÃÃo conduziu a uma deterioraÃÃo nas propriedades texturais dos adsorventes estudados, que sÃo essencialmente microporosos. Quanto maior a concentraÃÃo da soluÃÃo de impregnaÃÃo aumenta, maior à o preenchimento dos microporos por aminas. Hà evidÃncias experimentais de que parte da amina carregada liga covalentemente à estrutura zeolÃtica. A capacidade de adsorÃÃo de CO2 à sempre menor para amostras impregnadas do que para o suporte puro a 298 K, contudo em temperatura maiores, 348 K, à possÃvel observar melhorias. ZeÃlito X mantÃm textura e estrutura cristalina intacta nas amostras de troca-iÃnica. AdsorÃÃo de CO2 à reforÃada por cÃtions de compensaÃÃo menores e mais leves, como LÃtio, atingindo 4,82 mmol/g a 348 K e 1 bar. Em termos de capacidade de trabalho (entre 0,1 e 1 bar) a 298 K, o Ba em zeÃlito X tem um desempenho melhor do que os outros sÃlidos. Ele continua a ser estudado em trabalhos futuros a CO2/N2 e CO2/CH4 seletividade de tais materiais em condiÃÃes secas e Ãmidas.
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Folifac, Leo. "Performance of zeolite ZSM-5 synthesised from South African fly ash in the conversion of methanol to hydrocarbons." Thesis, Cape Peninsula University of Technology, 2018. http://hdl.handle.net/20.500.11838/2751.
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Thesis (Master of Engineering in Chemical Engineering)--Cape Peninsula University of Technology, 2018.Zeolites have found applications as heterogeneous or solid catalyst in the petrochemical and refining industries. Zeolite ZSM-5 in particular is a highly siliceous solid catalyst with a porous network that consists of medium pore structure (pore openings 5-5.5 A). The solid catalyst (ZSM-5) is well known for its high temperature stability and strong acidity, which makes it an established catalyst used for different petrochemical processes such as Methanol-To-Gasoline (MTG), isomerisation, disproportionation, and cracking. Unlike in the past, the synthesis of zeolite ZSM-5 from other sources that contains silica (Si) and alumina (Al) with the addition of a template (TPBr) as a structure-directing agent is eminent. Its synthesis can be achievable from coal fly ash that is a waste material and a cheap source of Si and Al. Coal fly ash is a waste material that is produced during the combustion of coal to generate electricity. The elemental composition of coal fly ash consists of mostly SiO2 and Al2O3 together with other significant and trace elements. Zeolite ZSM-5 catalyst synthesised from coal fly ash by previous authors required an excessive amount of additional source of silica even though the XRD spectra still show the presence of quartz and mullite phase in the final products. These phases prevented the use of fly ash (solid) as a precursor to synthesise zeolite ZSM-5 products. However, the synthesis of high purity zeolite ZSM-5 products by extracting silica and alumina from South African fly ash and then using it with small amounts of fumed silica was investigated This aim was achieved by fusing fly ash (FA) with sodium hydroxide (NaOH) under hydrothermal condition set at 550 oC for 1 hour 30 minutes. The quartz and mullite phase observed by previous authors was digested by the fusion process. Thereafter, the treatment of fused fly ash filtrate (FFAF) with concentrated H2SO4 (98-99%), precipitated silica and removed Al that therefore increased the Si/Al ratio from 1.97 in fly ash (FA) to 9.5 in the silica extract (named fused fly ash extract). This route was designed to improve the quality of the final products and reduced the amount of fumed silica added to the synthesis mixture prior to hydrothermal synthesis. In this line of investigation, the process of adding fumed silica to the hydrothermal gel was optimised. H-FF1 with a Si/Al ratio of 9.5 was synthesised using the silica extract without the addition of fumed silica. Its XRD, SEM and relative crystallinity results proved that H-FF1 was inactive and hence was not further characterised and utilised in the conversion of methanol to hydrocarbons (MTH). Purer phase zeolite ZSM-5 products (H-FF2 and H-FF3) that were synthesised from silica extract with the addition of small amounts of fumed silica were characterised and successfully used in the methanol to hydrocarbons (MTH) reaction. The synthesised ZSM-5 products had different Si/Al ratio, different morphology, crystal size, BET surface area, and relative crystallinity as well as different trends in the MTH reaction. It was also observed that H-FF2 and H-FF3 (pure phase) solid catalyst deactivated faster than the commercial H-ZSM-5 in the MTH reaction. However, the MTH conversion over H-FF2 competed with that of the commercial H-ZSM-5 within 3 hours of time on stream (TOS) but later deactivated at a faster rate. This was caused by the large crystal size and reduced BET surface area of H-FF2 when compared to the commercial H-ZSM-5. However, H-FF2 performed better than H-FF3 on stream (MTH reaction) due to its smaller crystal size and higher BET. This study has successfully utilised a route that synthesised high purity zeolite ZSM-5 products from the South African fused fly ash extract (FFAE) with the addition of small amounts of fumed silica. The properties of the synthesised zeolite ZSM-5 products (H-FF2 and H-FF3) were similar to that of the commercial H-ZSM-5 as well as active in the MTH reaction. This promoted the utilisation of a waste material (coal fly ash) to synthesise highly siliceous zeolite ZSM-5 products that avoided the presence of mineral phases from fly ash in the final products.
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Kiesow, Ina. "Herstellung und Charakterisierung von Kompositmembranen aus seitlich von einer Polymermatrix eingefassten Zeolithpartikeln." Doctoral thesis, Universitätsbibliothek Chemnitz, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-84896.
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Für die hochselektive technische Trennung von Stoffen hält die Natur eine optimale Lösung namens Zeolithe bereit. In dieser Arbeit wurden Zeolith 4A in Form von Partikeln und wenig permeables Polymer in einer Membran kombiniert. Die Partikel lagen dabei in einer Monolage vor und wurden lediglich seitlich vom Polymer eingefasst, sodass sie beide Oberflächen der Polymerschicht durchbrachen. Diese Einbettung zu so genannten Zeolithkompositmembranen erlaubt einen Stofftransport ausschließlich durch die hochselektiven Zeolithpartikel. Die Herstellung und Charakterisierung der Zeolithkompositmembranen stehen im Mittelpunkt der vorliegenden Arbeit. Für die Membranherstellung kam das Prinzip der partikelassistierten Benetzung einer Wasseroberfläche zum Einsatz. Hierfür wurden die Zeolithpartikel beschichtet und anschließend das unverändert zugängliche Porensystem mittels Thermogravimetrie in Wasseradsorptions-Desorptionsmessungen nachgewiesen. Aus beschichteten Partikeln und passendem Monomer konnten schichtdickenoptimierte Zeolithkompositmembranen hergestellt werden. Es wurde eine Permeabilität P für Wasserdampf von 49 barrer festgestellt, während die Gase Stickstoff und Sauerstoff keinen Transportnachweis zuließen (P < 0,03 barrer). Daraus ergeben sich Selektivitäten von über 1600. Die Durchlässigkeit für Wasser beweist ein offenes Porensystem, die Impermeabilität für Stickstoff und Sauerstoff deutet auf eine sehr geringe Defektdichte hin, was beste Voraussetzungen für Trennmembranen darstellt. Das Herstellungsprinzip soll als Vorlage für die Präparation maßgeschneiderter Kompositmembranen mit wählbarer Porengröße dienen. Vergleiche zu konventionellen Zeolithmembranen belegen, dass die partikelassistierte Benetzung die Methode der Wahl ist, partikelförmiges hochselektives Material optimal einzubetten, ohne die begehrten Permeationseigenschaften zu beeinträchtigenAn optimal material for highly selective separation processes can be found in zeolites. We prepared composite membranes composed of zeolite 4A particles and a polymer of low permeability. The particles formed a dense monolayer which were embedded into the polymer sheet in such a way that each particle prenetrates both the top and the bottom surface of the sheet. Only this embedding offffers a transport through the highly selective particles exclusively. This work focusses on these so called zeolite composite membranes, on their preparation and characterization. The preparation of the membranes was done via particle assisted wetting on a water surface. Therefore the zeolite particles were coated by a suitable silane agent and a blocking of the pore openings by the coating process was disproved by water adsorption-desorption measurements via TGA. Using the coated particles and a suitable monomer composite membranes could be formed and the optimum thickness was found. The membranes were permeable for water vapor (permeability P = 49 barrer), but impermeable for nitrogen and oxygene (P < 0,03 barrer (detection limit)). This results in a selectivity of above 1600. The permeability for water indicates that the molecules are transported through the zeolite channels. The impermeability for nitrogene and oxygene indicates a very low amount of defects. Furthermore the composite nature of the membrane reduces brittleness thus rendering it a promising candidate for separation technology with tailoring the pore size
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Hernandez, Tamargo Carlos Ernesto. "Computational study of layered zeolite MFI and titanium-substituted zeolite LTA and their applications in catalysis." Thesis, University College London (University of London), 2017. http://discovery.ucl.ac.uk/1573330/.
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In this thesis, we have examined the layered morphology of zeolite MFI and the titanium substitution of zeolite LTA by using a combination of density functional theory and interatomic potential-based calculations. Layered MFI zeolite allows a straightforward hierarchization of the pore system which accelerates mass transfer and increases its lifetime as a catalyst. We have performed a theoretical study of the structural features of the pure-silica and aluminium-substituted MFI nanosheets. We have analysed the effects of aluminium substitution on the vibrational properties of silanols as well as the features of protons as counter-ions. The formation of the two-dimensional system did not lead to appreciable distortions within the framework, whilst dehydration of aluminium-substituted silanols is both kinetic and thermodynamically favoured. In addition, we have analysed the strength of Brønsted acid (BA) sites located at the internal and external surfaces of zeolite MFI by adsorbing trimethylphosphine oxide (TMPO) as a probe molecule and correlating structural information to experimental 31P NMR data. We have been able to provide a possible explanation to the variable strength of the BA sites probed by TMPO by considering the basicity of the centres sharing the acid proton. In addition, we have examined the possible role of the Lewis acid sites located at the external surface of zeolite MFI to catalyse the tautomerization of phenolic-type compounds. The tautomerization has been conceived as a three-step process involving two protons transfers between the molecule and the zeolite, and the rotation of a dihedral angle. The energy barrier of each step is lower than 55 kJ/mol, suggesting that this transformation is easily accessible under standard reaction conditions. Finally, we have studied the structural, electronic and mechanical properties of the pure-silica zeolite LTA, as well as the single and double titanium-substituted material. The energetics of the titanium distribution within the zeolite framework suggest that the inclusion of a second titanium atom with configurations Ti-(Si)0-Ti, Ti-(Si)1-Ti and Ti-(Si)2-Ti is more favourable than the mono-substitution. The energetics of the dissociation of water on these Lewis acid sites indicate that this process is only favoured when two titanium atoms form a two-membered ring (2MR) sharing both hydroxy groups, Ti-(OH)2-Ti, showing that the presence of water may tune the distribution of titanium atoms within the framework of zeolite LTA.
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White, Jeremy Clayton. "Sensing, Separations and Artificial Photosynthetic Assemblies Based on the Architechture of Zeolite Y and Zeolite L." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1237641440.
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Najfach, Aaron Jacob. "EFFECT OF MANGANESE AND ZEOLITE COMPOSITION ON ZEOLITE-SUPPORTED NICKEL CATALYSTS FOR DRY REFORMING OF METHANE." Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami1501673873019245.
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White, Jeremy C. "Sensing, separations and artificial photosynthetic assemblies based on the architecture of zeolite Y and zeolite L." Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1237641440.
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