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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
231

A GAN BASED DUAL ACTIVE BRIDGE CONVERTER TO INTERFACE ENERGY STORAGE SYSTEMS WITH PHOTOVOLTAIC PANELS

Hassan , Hassan Athab 04 December 2017 (has links)
No description available.
232

Design and Control of an Isolated Battery-Driven Grid Interface with Three-Phase Dual-Active-Bridge Converter

Deqiang, Wang 22 June 2018 (has links)
Battery energy storage system (BESS) is promising to be implemented in residential applications for supporting PV integration, load shifting, and backup power purposes. For this application, 48V second-life battery draws more and more attentions for their cost-effectiveness, safe voltage level, reliability, and potential large market. This thesis proposes the comprehensive control and design of an isolated battery-driven grid interface (IBDGI) with the dual-active-bridge (DAB) converter for residential applications with 48V battery pack. The three-phase DAB converter is a promising candidate as the front-end DC/DC converter in the two-stage IBDGI due to its high efficiency, high power density, and low capacitance requirement. An effective design strategy for the three-phase DAB converter is proposed based on the zero-voltage-switching (ZVS) zone and back-ow power to achieve high efficiency for a wide operating voltage range and different load conditions. Based on the power loss model, an easily-implemented variable switching frequency operating method is proposed to further increase the efficiency at light load conditions. The dead-time effect is observed in the three-phase DAB converter. To avoid the dead-time effect and better understand the phenomena, a comprehensive analysis is proposed. All the cases of the dead-time effect in the three-phase DAB converter are analyzed in terms of the buck, boost, and matching states. The expressions of the transmission power, constraint conditions, and key time of the dead-time effect are derived for each state. The operation waveforms of the dead-time effect are also presented. The hybrid capacitor bank composed by the LC resonant lter with electrolytic capacitor and lm capacitor is utilized for the DC bus of the IBGDI. The electrolytic capacitors work as passive decoupling purpose while the lm capacitor is responsible for high switching harmonic ltering. Moreover, a current sharing method between the hybrid capacitor bank is proposed to extend the electrolytic capacitor's life. The LCL single-phase inverter is applied for the downstream of the IBDGI. A step-by-step design procedure of the LCL lter with passive damping is proposed for the 120V/240V dual grid-tied and standalone modes. The PR controllers are also designed for the LCL inverter for standalone and grid-tied modes. At the system level, a novel second harmonic current (SHC) reduction strategy is proposed for the IBDGI with the three-phase DAB converter by adding a load current feedforward (LCFF) path to the DAB voltage closed-loop controller. This method will suppress the SHC without modi cations of the original controller's bandwidth, which make it easy to be implemented. The small-signal model of the three-phase DAB converter is provided and veri ed by the step response. The parameter sensitivity analysis for the LCFF method is proposed to show that the SHC is well suppressed within ±20% parameter error. The proposed converter and control methods are veri ed by simulation and experimental results. / Thesis / Doctor of Philosophy (PhD)
233

Radiation induced graft copolymerization in wood

Werezak, G.N. 05 1900 (has links)
1. Investigations of styrene polymerized in wood using ionizing radiation as the chain initiator indicate that property improvements are of the same order as for thermally initiated polymerization. 2. Free radicals have been detected in irradiated cellulose, Dioxane lignin, Spruce Periodate lignin and Beaun’s “Isolated Native Lignin” as well as in wood subjected to radiation. Consequently, wood radical identification is not possible. 3. Analysis of radical concentrations and decay suggest the presence of one or more decaying radical species in irradiated wood. The persistent maximum in radical concentration found corresponds to one or two unique radical sites per molecule; possibly the terminal hydroxyl group. 4. Results suggest that in the grafting reaction the initiation is a direct radical-monomer couple and does not involve decomposing peroxides. / Thesis / Master of Engineering (ME)
234

The Effects of Amino Acids and Mitogen Activated Protein Kinase (MAPK) Inhibitors on Fluid Secretion and Ion Transport by Isolated Malpighian Tubules of Rhodnius Prolixus and Drosophila Melanogaster

Hazel, Matthew 09 1900 (has links)
Insect haemolynph typically contains very high levels of free amino acids 50 1 00 times that which is normal for mammalian plasma. This study examines the modulatory effects of amino acids on fluid secretion and ion transport by isolated MTs of Rhodnius prolixus and Drosophila melanogaster. The results show that the secretion rates of isolated Malpighian tubules of both Rhodnius and Drosophila are modulated by the presence of specific amino acids in the bathing saline. Some amino acids are stimulatory, some are inhibitory and others have little or no effect. Glutamine appears to be particularly important as a stimulant of fluid secretion. As well, secreted fluid pH and Na +concentration increase and K+ concentration decreases in response to glutamine. Amino acids do not appear to be important as metabolite. in Rhodnius tubules, nor do they act to draw significant amounts of water into the lumen by osmosis. Significant stimulation of fluid secretion can be achieved by physiological levels of particular amino acids, whereas those amino acids that inhibit fluid secretion only do so at concentrations much above those at which they occur naturally in the haemolymph. Amino acids are known to be compatible osmolytes and may be acting to maintain cell homeostasis and thus to sustain fluid secretion. The passive movement of amino acids may result in cell volume changes, and some form of osmosensor is may be coupled to activation of specific kinases to produce the observed increases in fluid secretion. The effects of several kinase inhibitors were therefore examined. The glutamine dependent increase in MT fluid secretion is blocked by two inhibitors of the stress activated protein kinase (SAPK) pathway, SP600125 and dicumoral. Inhibitors of other kinases (PKA, PKC, PKG, PI-3, p38, ERK and MEK), did not block glutamine's effects on fluid secretion rate. Alterations in cytoskeletal structure appear not to be required because cytoskeletal disrupting agents did not block the glutamine dependent inc~ease in fluid secretion, nor was the increase dependent upon protein synthesis. Results of this study are the first to suggest a role for the SAPK pathway in the control of fluid secretion rates by insect Malpighian tubules. / Thesis / Master of Science (MS)
235

Yttrium, Gadolinium, and Lutetium Based Endohedral Metallofullerenes: From Synthesis to Application

Zhang, Jianyuan 03 February 2014 (has links)
Endohedral metalofullerenes (EMFs) have emerged as an important class of nanomaterials with vast promise in applications of molecular devices and nanomedicines. This dissertation addresses the EMF research span from synthesis to application, with an emphasis of work on trimetallic nitride template (TNT) EMF and carbide clusterfullerenes (CCFs). As a general introduction, chapter 1 reviews the main literature in TNT EMF studies. Also key works in CCF area are highlighted to show the common feature and uniqueness of this class of EMF in comparison with other EMFs. In the last part of the chapter a list of milestone progress in EMF area has been summarized. Chapter 2 is devoted to the synthetic work on EMFs. Especially, for isotopic modification, the trial and actual EMF syntheses in efforts to introduce 13C, 89Y and 177Lu are described. The next three chapters address the structural characterization of EMFs. Chapter 3 focuses on structural studies of CCFs. With detailed interpretation of 13C NMR and DFT computational results for selected members of the Y2C2@C2n family, the influence of fullerene cage on the size and shape of the yttrium carbide cluster (Y2C2)4+ is investigated. It has also been established that the carbide cluster prefers a linear shape in sufficiently large fullerene cages but adopts a compressed butterfly shape in smaller cages where space is constrained. Chapter 4 presents a systemic examination of dipole moments in TNT EMFs. The first 13C NMR study of M3N@C2(22010)-C78 is achieved on Y3N@C2(22010)-C78. In addition, dipole moments of the M3N@C2n (n=39-44) family are probed by interpretation of chromatographic retention behavior, DFT computational results and single-crystal data. It has been found that TNT EMFs with pentalene motifs exhibit enhanced dipole moments due to the cluster-cage interplay. Chapter 5 provides full characterization of the M2C2@C1(51383)-C84 (M=Y, Gd) molecule, which contains the first example of an asymmetric fullerene cage with fused pentagons. Furthermore, it is suggested that the C1(51383)-C84 cage is capable of a cascade of rearrangements into high symmetry and stable fullerene cages via well-established mechanistic steps, namely, extrusion of C2 units from pentalene or indene motifs and Stone-Wales transformations. As an important intermediate in the formation of high symmetry fullerene cages, the C1(51383)-C84 represents a missing link that implies the "top-down" fullerene formation mechanism. Chapter 6 describes the endeavor to functionalize two exotic EMFs, the room-temperature radical heterometallofullerene Gd2@C79N, and the egg-shaped TNT EMF Gd3N@C84. The reactivity of Gd2@C79N is directly compared to Y2@C79N, Gd3N@C80 and Sc3N@C80 in two reactions and the paramagnetic Gd2@C79N is proven to be very inert toward many known common fullerene cage reactions. Eventually both EMFs have been successfully functionalized via the Bingel reaction, and the derivatives are characterized with HPLC and mass-spectrometry. Chapter 7 compares the effective magnetic moment of Gd3N@C80 and Gd3N@C84, together with the previously reported Gd@C82. The magnetic moment has a second-order contribution to the T1 relaxivity and thereby is an important factor to evaluate an EMF's value in application as MRI contrast agents. Furthermore the influence of cluster motion to magnetic behavior in TNT EMF is discussed. / Ph. D.
236

Synchronous-Conduction-Mode Tapped-Inductor Buck Converter for Low-Power, High-Density Application

Yeh, Chih-Shen 06 November 2017 (has links)
General-purpose step-down converter is essential in electronic system for processing energy from high-voltage rail to low-voltage circuits. The applications can be found at the auxiliary supplies in automobile, industrial and communication systems. Buck converter is a common circuit topology to fulfill step-down conversion, especially in low-power application since it is well-studied and straightforward. However, it suffers from low duty cycle under high step-down condition, and typically operates in continuous conduction mode (CCM) that generates large switching loss. On the other hand, as an extension of the buck converter, tapped-inductor (TI) buck converter has larger duty cycle while maintaining the structural simplicity. Therefore, the main objective of this thesis is to explore the potential of TI buck converter as a wide conversion range, high power density and high efficiency topology for low power application. To achieve high efficiency at switching frequency of MHz-level, synchronous conduction mode (SCM) is applied for turn-on losses elimination. The operation principle and power stage design of SCM TI buck is first introduced. The design of high switching frequency coupled inductor is emphasized since its size plays a critical role in power density. Loss breakdown is also provided to perform a comprehensive topological study. Secondly, detailed zero-voltage-switching (ZVS) condition of SCM TI buck is derived so that the converter does not experience redundant circulating energy. The experimental results of 15-W SCM TI buck converter prototypes are provided with 90.7% of peak power stage efficiency. The size of coupled inductor is down to 116 mm3. To enhance light-load efficiency, a variable frequency control scheme based on derived ZVS conditions is implemented with the switching frequency ranging from 2 MHz to 2.9 MHz. / Master of Science / General-purpose step-down converter is essential in electronic system for processing energy from high-voltage rail to low-voltage circuits. The applications can be found at the auxiliary supplies in automobile, industrial and communication systems. Typically, the ultimate goals of general-purpose step-down converter are versatility, high efficiency and compact size. Recently, tapped-inductor (TI) buck converter is studied since it could overcome the drawback of commonly used buck converter under high step-down conversion. Therefore, the potential of TI buck converter as a general-purpose step-down converter candidate is explored in this thesis, including control method, hardware design, etc. The thesis verifies that TI buck converter could have compact size while remaining efficient and adaptable.
237

A High-Efficiency Hybrid Resonant Microconverter for Photovoltaic Generation Systems

LaBella, Thomas Matthew 18 September 2014 (has links)
The demand for increased renewable energy production has led to increased photovoltaic (PV) installations worldwide. As this demand continues to grow, it is important that the costs of PV installations decrease while the power output capability increases. One of the components in PV installations that has lots of room for improvement is the power conditioning system. The power conditioning system is responsible for converting the power output of PV modules into power useable by the utility grid while insuring the PV array is outputting the maximum available power. Modular power conditioning systems, where each PV module has its own power converter, have been proven to yield higher output power due to their superior maximum power point tracking capabilities. However, this comes with the disadvantages of higher costs and lower power conversion efficiencies due to the increased number of power electronics converters. The primary objective of this dissertation is to develop a high-efficiency, low cost microconverter in an effort to increase the output power capability and decrease the cost of modular power conditioning systems. First, existing isolated dc-dc converter topologies are explored and a new topology is proposed based on the highly-efficient series resonant converter operating near the series resonant frequency. Two different hybrid modes of operation are introduced in order to add wide input-voltage regulation capability to the series resonant converter while achieving high efficiency through low circulating currents, zero-current switching (ZCS) of the output diodes, zero-voltage switching (ZVS) and/or ZCS of the primary side active switches, and direct power transfer from the source to the load for the majority of the switching cycle. Each operating mode is analyzed in detail using state-plane trajectory plots. A systematic design approach that is unique to the newly proposed converter is presented along with a detailed loss analysis and loss model. A 300-W microconverter prototype is designed to experimentally validate the analysis and loss model. The converter featured a 97.7% weighted California Energy Commission (CEC) efficiency with a nominal input voltage of 30 V. This is higher than any other reported CEC efficiency for PV microconverters in literature to date. Each operating mode of the proposed converter can be controlled using simple fixed-frequency pulse-width modulation (PWM) based techniques, which makes implementation of control straightforward. Simplified models of each operating mode are derived as well as control-to-input voltage transfer functions. A smooth transition method is then introduced using a two-carrier PWM modulator, which allows the converter to transition between operating modes quickly and smoothly. The performance of the voltage controllers and transition method were verified experimentally. To ensure the proposed converter is compatible with different types of modular power conditioning system architectures, system-level interaction issues associated with different modular applications are explored. The first issue is soft start, which is necessary when the converter is beginning operation with a large capacitive load. A novel soft start method is introduced that allows the converter to start up safely and quickly, even with a short-circuited output. Maximum power point tracking and double line frequency ripple rejection are also explored, both of which are very important to ensuring the PV module is outputting the maximum amount of available power. Lastly, this work deals with efficiency optimization of the proposed converter. It is possible to use magnetic integration so that the resonant inductor can be incorporated into the isolation transformer by way of the transformer leakage inductance in order to reduce parts count and associated costs. This chapter, however, analyzes the disadvantages to this technique, which are increased proximity effect losses resulting in higher conduction losses. A new prototype is designed and tested that utilizes an external resonant inductor and the CEC efficiency was increased from 97.7% to 98.0% with a marginal 1.8% total cost increase. Additionally, a variable frequency efficiency optimization algorithm is proposed which increases the system efficiency under the high-line and low-line input voltage conditions. This algorithm is used for efficiency optimization only and not control, so the previously presented simple fixed-frequency modeling and control techniques can still be utilized. / Ph. D.
238

Higher-Form Symmetry and Eigenstate Thermalization Hypothesis / 高次対称性と固有状態熱化仮説

Fukushima, Osamu 25 March 2024 (has links)
京都大学 / 新制・課程博士 / 博士(理学) / 甲第25111号 / 理博第5018号 / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)准教授 福間 將文, 教授 杉本 茂樹, 教授 橋本 幸士 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM
239

Design And Analysis Of A New Buck-Boost Converter With A Low-Side Switch

Awidah, Abdullah 01 June 2024 (has links) (PDF)
This work explores the design, simulation, construction, and analysis of a novel Non-isolated DC-DC Buck-Boost converter which has the advantage of incorporating a low-side switch compared to the traditional buck-boost which requires a high-side switch. This allows the use of a low-side driver which further simplifies the design and operation of the converter. The proposed Buck-Boost converter was constructed to provide -24 V output from an input range of 12V-18V with 15V nominal input at 10W maximum output power utilizing 500kHz switching frequency. Findings from simulations and hardware tests verify that the converter effectively provides the desired -24 V output at varying loads with less than 3% ripple. At the nominal input voltage, the efficiency of the converter reaches 82.37% at full load and peak efficiency of 88.5% at 20% load. Moreover, the input voltage ripple of the proposed non-isolated converter reached 8.4% at full load, due to the pulsating nature of the input current. Overall, results verify the feasibility of the proposed non-isolated Buck-Boost converter as an alternative solution for the conventional buck-boost with the advantage of a low side switch while maintaining a low component count.
240

Diseño racional de materiales zeolíticos: efectos de confinamiento y control de centros metálicos en posiciones de red y extra-red en aplicaciones de interés

Rodríguez Fernández, Aida 29 February 2024 (has links)
[ES] Las zeolitas son catalizadores ampliamente utilizados en una gran variedad de procesos químicos, por lo que la optimización de sus propiedades físico-químicas es fundamental para mejorar su aplicación en procesos de interés industrial y medioambiental. En la presente tesis doctoral se proponen diversas metodologías de síntesis directa y post-sintéticas con el fin de controlar aspectos importantes de estos materiales desde la escala microscópica hasta la molecular y atómica, así como su implicación directa en su aplicación como catalizadores y/o materiales conductores. En un primer objetivo, se estudia la influencia del tamaño de cristal y la estructura zeolítica en la transformación selectiva de CO2 hacia productos de interés como olefinas y aromáticos cuando se combina con un catalizador de hierro dopado con potasio. Por un lado, la estructura zeolítica tipo MFI (poro medio) permite maximizar la formación de productos aromáticos, mientras que las zeolitas tipo CHA (poro pequeño) y beta (poro grande) favorecen la formación de olefinas ligeras en distinta proporción. La utilización de las zeolitas ácidas nanocristalinas permite incrementar la formación de olefinas ligeras y aumentar el tiempo de vida de los catalizadores bifuncionales. Asimismo, se estudia el efecto del confinamiento a nivel molecular de diferentes estructuras zeolíticas de poro pequeño con distinto tipo de cavidad para la reacción de metanol a olefinas (MTO), pudiéndose correlacionar la selectividad hacia distintas olefinas ligeras con un parámetro teórico que depende de las dimensiones y la forma de las cavidades de los materiales microporosos. En segundo lugar, se estudia la estabilización de distintas especies metálicas en posiciones extra-red de los materiales zeolíticos, controlando su formación desde átomos individuales a clústeres y/o nanopartículas. La estructura de la zeolita CHA permite encapsular nanopartículas de Pt en el interior de sus cavidades, que son activas y estables para la reacción de oxidación de CO incluso tras tratamientos de envejecimiento a elevadas temperaturas. Por otro lado, se racionaliza la formación de nanopartículas de germanio dispersas en distintas matrices zeolíticas híbridas aprovechando la labilidad del germanio en la red cristalina de las mismas para su aplicación como materiales conductores. Se realiza una optimización de dichos materiales híbridos orgánicos-inorgánicos basados en nanopartículas de Ge mediante diversos tratamientos post-sintéticos, maximizando la dispersión de las nanopartículas y la formación de especies carbonosas para, finalmente, evaluar sus propiedades como materiales conductores. En último lugar, se utiliza esa labilidad del Ge en posiciones cristalinas de las zeolitas como estrategia para controlar a escala atómica la incorporación selectiva de distintos heteroátomos (Si y Sn). La síntesis de la estructura ITT con poros extra-grandes está limitada a bajas relaciones de Si/Ge, presentando por tanto una limitada estabilidad hidrotermal. Por ello, se lleva a cabo una sustitución isomórfica de átomos de Ge por átomos de Si, mejorando la estabilidad hidrotermal de dicho material para su aplicación en la reacción de craqueo catalítico de un gasoil de vacío, posibilitando su regeneración, y obteniendo similar selectividad a diésel y más propileno que con la muestra de origen. Por otro lado, se incorpora selectivamente Sn en la estructura BEC (polimorfo C de la zeolita beta) mediante tratamientos post-sintéticos en los defectos estructurales generados tras la eliminación de átomos de Ge, favoreciéndose la formación de sitios "abiertos" de Sn, que han demostrado ser más activos para reacciones de moléculas oxigenadas en comparación a los sitios "cerrados" de Sn. Las ventajas catalíticas del material Sn-BEC sintetizado se demuestran en la reacción Meerwein-Ponndorf-Verley-Oppenauer (MPVO), obteniéndose mayores velocidades de reacción por sitio de Sn "abierto" que con la zeolita Sn-beta(F) convencional. / [CA] Les zeolites són catalitzadors àmpliament utilitzats en una gran varietat de processos químics, per la qual cosa l'optimització de les seues propietats fisicoquímiques és fonamental per a millorar la seua aplicació en processos d'interès industrial i mediambiental. En la present tesi doctoral es proposen diverses metodologies de síntesi directa i post-sintètiques amb la finalitat de controlar aspectes importants d'aquests materials des de l'escala microscòpica fins a la molecular i atòmica, així com la seua implicació directa en la seua aplicació com a catalitzadors i/o materials conductors. Com a primer objectiu, s'estudia la influència de la grandària de cristall i l'estructura zeolítica en la transformació selectiva de CO¿ cap a productes d'interès com a olefines i aromàtics quan es combina amb un catalitzador de ferro dopat amb potassi. D'una banda, l'estructura zeolítica tipus MFI (porus mitjà) permet maximitzar la formació de productes aromàtics, mentre que les zeolites tipus CHA (porus xicotet) i beta (porus gran) afavoreixen la formació d'olefines lleugeres en diferent proporció. La utilització de les zeolites àcides nanocristalines permet incrementar la formació d'olefines lleugeres i augmentar el temps de vida dels catalitzadors bifuncionals. Així mateix, s'estudia l'efecte del confinament a nivell molecular de diferents estructures zeolítiques de porus xicotet amb diferent tipus de cavitat per a la reacció de metanol a olefines (MTO), podent-se correlacionar la selectivitat cap a diferents olefines lleugeres amb un paràmetre teòric que depèn de les dimensions i la forma de les cavitats dels materials microporosos. En segon lloc, s'estudia l'estabilització de diferents espècies metàl·liques en posicions extra-xarxa dels materials zeolítics, controlant la seua formació des d'àtoms individuals a clústers i/o nanopartícules. L'estructura de la zeolita CHA permet encapsular nanopartícules de Pt a l'interior de les seues cavitats, actives i estables per a la reacció d'oxidació de CO fins i tot després de tractaments d'envelliment a elevades temperatures. D'altra banda, es racionalitza la formació de nanopartícules de germani disperses en diferents matrius zeolítiques híbrides aprofitant la labilitat del germani en la xarxa cristal·lina de les mateixes per a la seua aplicació com a materials conductors. Es realitza una optimització d'aquests materials híbrids orgànics-inorgànics basats en nanopartícules de Ge mitjançant diversos tractaments post-sintètics, maximitzant la dispersió de les nanopartícules i la formació d'espècies carbonoses per a, finalment, avaluar les seues propietats com a materials conductors. En últim lloc, s'utilitza eixa labilitat del Ge en posicions cristal·lines de les zeolites com a estratègia per a controlar a escala atòmica la incorporació selectiva de diferents heteroàtoms (Si i Sn). La síntesi de l'estructura ITT amb porus extra-grans està limitada a baixes relacions de Si/Ge, presentant per tant una limitada estabilitat hidrotermal. Per això, es du a terme una substitució isomòrfica d'àtoms de Ge per àtoms de Si, millorant l'estabilitat hidrotermal d'aquest material per a la seua aplicació en la reacció de craqueig catalític d'un gasoil de buit, possibilitant la seua regeneració i obtenint una selectivitat similar a dièsel i més propilè que amb la mostra d'origen. D'altra banda, s'incorpora selectivament Sn en l'estructura BEC (polimorf C de la zeolita beta) mitjançant tractaments post-sintètics als defectes estructurals generats després de l'eliminació d'àtoms de Ge, afavorint-se la formació de llocs "oberts" de Sn, que han demostrat ser més actius per a reaccions de molècules oxigenades en comparació als llocs "tancats" de Sn. Els avantatges catalítics del material Sn-BEC sintetitzat es demostren a la reacció Meerwein-Ponndorf-Verley-Oppenauer (MPVO), obtenint-se majors velocitats de reacció per lloc de Sn "obert" que amb la zeolita Sn-beta(F) convencional. / [EN] Zeolites are catalysts used in many chemical processes of industrial and environmental interest. The optimization of the physicochemical properties of these materials is essential to improve their efficiency and attractiveness to current and future technologies. This doctoral thesis aimed to control relevant aspects of the zeolites at the microscopic, molecular, and atomic scale that have a direct effect on their application as catalysts and conductive materials. With this in mind, several methodologies for the direct synthesis of zeolites and several post-synthetic treatments were proposed. Firstly, the influence of crystal size and zeolitic structure on the selective transformation of CO2 towards products of interest such as olefins and aromatics is studied when combined with an iron catalyst doped with potassium. On the one hand, the MFI-type zeolitic structure (medium pore) allows the formation of aromatic products to be maximized. Meanwhile, the CHA (small pore) and BEA (large pore) zeolites favour the production of light olefins in different proportions. The use of nanocrystalline acid zeolites allows to increase the production of light olefins and increases the lifetime of the bifunctional catalysts. Likewise, the effect of confinement at the molecular level of different small-pore zeolitic structures with different types of cavities for the reaction of methanol to olefins (MTO) is studied. Using a theoretical parameter, it was finally possible to correlate the selectivity towards different light olefins with the type of cavities in the microporous materials. Secondly, the stabilization of different metallic species in extra-framework positions of the zeolitic materials is studied by controlling the formation from the individual atoms towards clusters and/or nanoparticles. The structure of the CHA zeolite allows Pt nanoparticles to be encapsulated inside its cavities, which continues being active and stable for the CO oxidation reaction even after aging treatments at high temperatures. On the other hand, the formation of germanium nanoparticles dispersed in different hybrid zeolitic matrices is rationalized by taking advantage of the lability of germanium in their crystalline framework for their application as conductive materials. The optimization of these hybrid organic-inorganic materials based on Ge nanoparticles is carried out through various post-synthetic treatments by maximizing the dispersion of the nanoparticles and the formation of carbonaceous species to evaluate their properties as conductive materials. Finally, the mentioned lability of Ge in crystalline positions is used as a strategy to control the selective incorporation of different heteroatoms (Si and Sn) at the atomic scale. The fact that the synthesis of the ITT structure with extra-large pores is limited to low Si/Ge ratios leads to reduced hydrothermal stability. Therefore, an isomorphic substitution of Ge atoms with Si atoms is carried out. It improved the hydrothermal stability of the material to be applied in the catalytic cracking of a vacuum gasoil, enabling its regeneration. Moreover, the modified material presents similar selectivity to diesel and yields more propylene as compared to the original sample. Also, Sn is selectively incorporated into the BEC structure (polymorph C of beta zeolite) through post-synthetic treatments in the structural defects generated after the elimination of Ge atoms, favouring the formation of "open" Sn sites. It has been shown that this kind of site is more active for reactions involving oxygenated molecules compared to the "closed" sites of Sn. The catalytic advantages of the synthesized Sn-BEC material are demonstrated in the Meerwein-Ponndorf-Verley-Oppenauer (MPVO) reaction. Higher reaction rates per "open" Sn site than with the conventional Sn-beta(F) zeolite were obtained. / Rodríguez Fernández, A. (2024). Diseño racional de materiales zeolíticos: efectos de confinamiento y control de centros metálicos en posiciones de red y extra-red en aplicaciones de interés [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/202870

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