Дисертації з теми "Nano-catalysis"
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Elrabei, Abubakar Osman Zina <1994>. "Supramolecular Catalysis in Confined Nano-space." Master's Degree Thesis, Università Ca' Foscari Venezia, 2022. http://hdl.handle.net/10579/20687.
Повний текст джерелаAhn, Sun Yhik. "Carbon based nano-composite interfaces for electro-catalysis." Thesis, University of Bath, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.698985.
Повний текст джерелаXu, Jiahui. "Catalytic properties of nano ceria in heterogeneous catalysis." Thesis, University of Oxford, 2010. http://ora.ox.ac.uk/objects/uuid:02e68ff9-ce28-475a-bd08-6b60bcda64e7.
Повний текст джерелаJegadeesan, Gautham. "Environmental catalysis using nano-sized bimetallic particles : selenium remediation /." Available to subscribers only, 2005. http://proquest.umi.com/pqdweb?did=1068236761&sid=29&Fmt=2&clientId=1509&RQT=309&VName=PQD.
Повний текст джерелаZhang, Yeshui. "Hydrogen and carbon nano-materials from the pyrolysis-catalysis of wastes." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/18509/.
Повний текст джерелаKim, Kyungduk. "Novel Nanocatalyst for the Selective Hydrogenation of Bio-Oil Model Compounds." Thesis, The University of Sydney, 2016. http://hdl.handle.net/2123/16353.
Повний текст джерелаGarrido, Torres José A. "Density functional theory investigations of molecules on surfaces : from nano-electronics to catalysis." Thesis, University of St Andrews, 2017. http://hdl.handle.net/10023/15618.
Повний текст джерелаSnyder, Brian. "An investigation into bimetallic hollow nanoparticles in catalysis." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47614.
Повний текст джерелаDuanmu, Chuansong. "Expanding applications of iron oxide nanoparticles by surface functionalization : from magnetic resonance imaging to nano-catalysis /." Available to subscribers only, 2009. http://proquest.umi.com/pqdweb?did=1967917191&sid=4&Fmt=2&clientId=1509&RQT=309&VName=PQD.
Повний текст джерелаLi, Richard Ph D. Massachusetts Institute of Technology. "Catalysis and manufacturing of two-scale hierarchical nano- and microfiber advanced aerospace fiber-reinforced plastic composites." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120419.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (pages 195-210).
The development of hierarchical nanoengineered "fuzzy fiber" aerospace fiber-reinforced plastic (FRP) composite laminates holds the potential for enabling future generations of lightweight, durable, and multifunctional vehicle structures. By reinforcing the weak matrix-rich regions between individual fibers and plies, the circumferential growth of aligned carbon nanotubes (A-CNTs) on carbon microfibers (CFs) enables new composites with improved strength, toughness, electrical and thermal properties. While these improvements have been empirically demonstrated on alumina fiber FRPs, CNT growth degrades the CFs and sacrifices in-plane FRP properties for the benefits of CNT reinforcement. This thesis presents novel and scalable methods for realizing advanced fuzzy carbon fiber reinforced plastic (fuzzy CFRP) composite laminates with retained CF and interlaminar strength properties. Earth-abundant sodium (Na) is revealed as a new facile catalyst for CNT growth that allows for direct deposition of the catalyst precursor on carbon fabrics without any fiber pretreatments. This new catalyst discovery also enables high-yield CNT growth on a variety of low-temperature substrates. Simultaneously, this finding has led to other novel findings in carbon nanostructure catalysis including a core-shell morphology and the use of other alkali metals (e.g., potassium) for CNT growth. Towards the development of advanced composites, vacuum-assisted resin infusion processes are studied and refined, resulting in high-quality woven and unidirectional fuzzy (via Na-catalysis of CNTs) CFRP laminates. Growth uniformity improvement studies yielded strategies for increasing the quantity of CNT reinforcement within matrix-rich regions. Moreover, a new commercial unidirectional fabric enables the first retention of CF properties concomitant with interlaminar shear strength retention in the fuzzy CFRP architecture. The contributions of this thesis extend beyond CF composites: techniques developed for improving fuzzy CF synthesis were applied towards demonstrating A-CNT growth on SiC woven fabric, desired for creating damage tolerant and multifunctional lightweight vehicle systems. These advances pave the way for improvements in catalysis of nanostructures, electronics interfaces, energy storage devices, and advanced composite materials.
by Richard Li.
Ph. D.
Duanmu, Chuansong. "EXPANDING APPLICATIONS OF IRON OXIDE NANOPARTICLES BY SURFACE FUCNTIONALIZATION: FROM MAGNETIC RESONANCE IMAGING TO NANO-CATALYSIS." OpenSIUC, 2009. https://opensiuc.lib.siu.edu/dissertations/110.
Повний текст джерелаLi, Wai Chung. "Preparation and characterization of noble metal-magnetite hybrid nano/micro composites towards drug delivery and heterogeneous catalysis." HKBU Institutional Repository, 2019. https://repository.hkbu.edu.hk/etd_oa/668.
Повний текст джерелаKisurin, Vitaly Mr. "Laser Vaporization Controlled Condensation and Laser Irradiation in Solution for the Synthesis of Supported Nanoparticle Catalysts." VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4636.
Повний текст джерелаHajar, Yasmine. "Effect of Electrochemical Promotion and Metal-Support Interaction on Catalytic Performance of Nano-catalysts." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39701.
Повний текст джерелаHarmel, Justine. "Synthèse de nano-catalyseurs hybrides à base de cobalt pour la catalyse Fischer-Tropsch." Thesis, Toulouse, INSA, 2016. http://www.theses.fr/2016ISAT0035/document.
Повний текст джерелаDue to the decreasing the oil resources, and because of the the fluctuations of the price as a result of the geopolitical context, the Fischer-Tropsch synthesis, that enables the production of hydrocarbons form the syngas mixture (CO and H2) in the presence of a catalyst based on cobalt or iron, has recently gained a renewed interest from industrial as well as form the academic communities. Although this reaction was discovered in 1923 by the Germans Franz Fischer and Hans Tropsch, the mechanisms that come into play during this reaction and the crucial properties of the catalyst properties remain uncertain. In this context, the work presented in this thesis, aims to investigate the impact of parameters such as the crystallographic structure and the shape of the cobalt nano-objects, which is the active phase of the catalyst for this reaction. For this purpose, model cobalt nano-objects were synthetized and their catalytic properties were studied. As a first step, a cobalt based catalyst exhibiting an hcp crystallographic structure and an anisotropic shape was prepared via a synthetic route involving the decomposition of an organometallic precursor of cobalt and leading to the formation of anisotropic cobalt nano-objects. Catalytic tests were then conducted in a slurry reactor, in collaboration with an industrial partner, IFP-EN. This collaboration allowed performing catalytic studies under conditions that are very close to the actual industrial conditions. These studies revealed an increased stability of these catalysts compared to reference catalysts that deactivate with time. Finally, several cobalt-based catalysts, supported on innovative supports, such as macrostuctured supports, allowing a better control of the exothermicity, were prepared and their catalytic properties studied on a fixed-bed reactor that was set up during the course of this thesis work
Wierzbicki, Dominik. "New nano-oxide catalysts for CO2 hydrogenation reaction." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS420.
Повний текст джерелаThe increasing concentration of CO2 in the atmosphere, which is considered to be one of the anthropogenic sources of global warming, increased concerns and social awareness about the climate change. The strategies for CO2 emissions reduction may be divided into (i) carbon capture and storage (CCS) and (ii) carbon capture and utilization (CCU) groups. In comparison to CCS, the CCU technologies allow to convert carbon dioxide into a valuable product. Thus, CCU methods are treating CO2 as raw material and not as pollutant. Among the processes that convert CO2 into a valuable compound is carbon dioxide methanation. In this process carbon dioxide is hydrogenated to methane with hydrogen supplied via water electrolysis using e.g. excess energy. It should be mentioned that some industrial scale installation already exists (up to 10MW). The literature study suggests that the most appropriate active metal in this process is nickel due to (i) very good catalytic activity (comparable to noble metals), (ii) low cost and (iii) availability. As reported in literature, different strategies were implemented in order to increase the activity of Ni-based catalysts in CO2 methanation. The most common ones include using various supports, changing the content of nickel or introduction of promoters. These strategies change the physicochemical properties, such as interaction of nickel active phase with the support, which inhibits sintering and increases the CO2 adsorption capacity. The latter property , as well as stability towards sintering, are crucial in order to obtain an active, selective and stable catalyst for CO2 methanation reaction. The application of mixed oxides of magnesia and alumina allows to introduce these properties, as MgO possesses basic character and is strongly bonded with NiO due to the formation of a solid solution of NiO-MgO. Hydrotalcites seem to be the highly promising materials for such application, because NiO, MgO and Al2O3 may be easily introduced into such materials. Literature studies confirmed that Ni-containing hydrotalcites are very active in CO2 methanation. Therefore, the goal of this PhD thesis was to evaluate the catalytic properties of Ni-containing hydrotalcite-derived mixed oxide materials in CO2 methanation. As the literature review showed that there are not many studies focused on such materials in the mentioned field, this work was focused on filling these gaps. The work was divided into four parts: (i) evaluation of catalytic properties of hydrotalcites containing various amounts of nickel in brucite-like layers, (ii) evaluation of catalytic properties of nickel-containing hydrotalcites promoted with Fe or La, (iii) evaluation of the effect of different methods of introduction of La on catalytic properties of Ni-hydrotalcites, and (iv) optimization of the catalysts and examination of promoting effect of La. In order to correlate the changes of physico-chemical properties, of the materials prepared by co-precipitation, the catalysts were characterized by means of elemental analysis (ICP-MS or XRF), XRD, FTIR, low temperature nitrogen sorption, H2-TPR and CO2-TPD. Additionally, selected catalysts were characterized using TEM, XANES and XES. The catalytic tests were carried out in the temperature range from 250°C to 450°C. In order to elucidate the promoting effect of lanthanum introduction operando XANES and XES under various reaction conditions were implemented. (...)
Assaud, Loic. "Fonctionnalisation de substrats nano-structurés pour la conversion et le stockage de l'énergie." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4049.
Повний текст джерелаIn order to meet the growing needs in today's society that requests more transportation and portable devices, energy production, conversion and storage systems are now experiencing real changes. To fabricate systems able to generate a controlled and renewable energy, nanoscience and nanotechnology are leading research fields. The work presented in this manuscript describes the fabrication of nanosized, large-scale organized structures. These nanostructures have been functionalized through film and particle synthesis using a chemical vapor deposition method: the Atomic Layer Deposition (ALD).Thus, metal/insulator/metal (MIM) systems are fabricated on highly-ordered high-aspect ratio porous alumina. The materials that have been deposited are TiN, Al2O3 and HfO2. The aim is to produce high performance nanocapacitors that can be used for data storage (DRAM) application or for energy storage in small devices such as RFID.In a second part, metallic catalysts such as Pd/Ni have been deposited on alumina membranes for formic acid electro-oxidation. Similarly, TiO2 nanotubes have been fabricated by anodic oxidation and they have been functionalized with Pd nanoparticles for ethanol electro-oxidation. Both studied systems can be used as anode catalysts in direct liquid fuel cells.Finally, the last part of this work has consisted in the study of Cu2O, as a p-type semiconductor, that has been electrochemically deposited onto TiO2 nanotubes (n-type semiconductor). The resulting p/n junction can be interesting for solar energy photoconversion
Mongin, Cédric. "Synthèse et étude de cages moléculaires photo-modulables et génération de nano-cristaux d’or par photo-catalyse supramoléculaire." Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR14996/document.
Повний текст джерелаThe goals of this thesis are organized around two major axes: the synthesis and study of photo-gated molecular cages, and the generation of gold nanocrystals by supramolecular photocatalysis. These two themes are connected by the use of the photochemical and photophysical properties of a common chromophore, 9,10-diphenylanthracene (DPA). Three-dimensional photo-gated cage-like architectures were designed and synthesized. Various synthetic strategies based on the combined use of the 2,4,6-trichloro-1,3,5-triazine unit and "click" chemistry reactions (olefin metathesis, Huisgen cycloaddition) were employed for the synthesis. In the presence of oxygen, sensitized or direct irradiation of the DPA chromophore forms the corresponding endoperoxide derivative, thereby modulating the binding properties of the cage. The study and the modulation of the recognition properties were performed on various alkali metal cations and a strong binding of sodium and cesium was evidenced by fluorescence emission and UV-visible absorption spectroscopy. The cages investigated possessed high association constants towards sodium and cesium cations (logK = 8.7 for the sodium cation) which could be reversibly increased by a factor 10 and 20 for sodium and cesium, respectively, upon formation of the endoperoxide. Supramolecular photocatalysis of gold(III) reduction based on the DPA chromophore was also studied for the preparation of uncapped gold nanocrystals. The combination of the DPA chromophore with thioether chains allows the formation of a complex in the organic phase by extraction of gold(III) chloride from an aqueous phase. Irradiation at 400 nm enables the reduction gold(III) by energy transfer from the 9,10-diphenylanthracene followed by oxidation of the solvent. The gold atoms are subsequently released in the aqueous phase to form uncapped nanocrystals characterized using TEM, XPS, AFM, and DLS techniques. Furthermore, the process is catalytic in toluene, where a continuous flow reactor was developed. The latter allowed an average catalytic turnover of 150 to be determined
Souza, Edith Marie Malateaux de. "Adesivo de contato de policloropreno base aquosa nanoaditivado e condicionado magneticamente." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-21062016-113107/.
Повний текст джерелаCurrently, the aqueous based polychloroprene contact adhesive presents an adhesion capacity variation between 1,15 and up to 2,75 kgf/cm2. However, the solvent based polychloroprene adhesives support average tensions of shearing of 3,8 kgf/cm2. This research is an innovative proposal for magnetic conditioning of the aqueous based polychloroprene contact adhesive with the purpose of increasing the adherence capacity between the adhesive and the substrate. To promote an increase of adhesion to the aqueous based polychloroprene contact adhesive, we formulated one adhesive using a nano-additive, carbon dioxide as catalyst, and a magnetic conditioning process before the phase of application on the substrates. The results obtained show an average increase of 292 % in the shearing tension of the adhesive magnetically conditioned when compared with an adhesive of the same formulation without the magnetic conditioning and 122 % increase when compared to the commercial aqueous based polichloroprene adhesive.
Parulkar, Aamena. "Developing Synthesis and Characterization Methods for Enhancing Material Performance." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1542739064703435.
Повний текст джерелаLambert, Romain. "Nouveaux copolymères et nanostructures dérivés de liquides ioniques à base d'imidazoliums : applications en catalyse et comme additifs conducteurs ioniques." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0306/document.
Повний текст джерелаPoly(ionic liquid)s (PILs) in the form of random copolymers, single chain nanoparticles(SCNPs), or self assembled block copolymers have been used as N-heterocyclic carbenes(NHCs) precursors for the purpose of organic and organometallic catalysis. Introducing acetate derivative counter anion in imidazolium based PIL units enable in situ generation of catalyticallyactive NHC. SCNPs have been specially designed along two strategies including, firstly, a self quaternization reaction involving two antagonists groups supported on to the polymer chain and,secondly, an organometallic complexation featuring palladium salt. Both polymeric precursors were obtained using RAFT as controlled polymerization method. Amphiphilic block copolymers composed of a PIL block functionalized by palladium have been synthesized by RAFT and self-assembled in water, leading to micellar structures. Confinement effect has been demonstrated through Suzuki and Heck coupling in water showing kinetic gain compared to molecular homologue in addition to an easier recycling method.Finally, PIL-benzimidazolium based block copolymers with lithium bis(trifluoromethane)-sulfonylimide anion have been developed as ionic conductor doping agent for PS-PEO matrix. Thin films blends with minimum doping agent amount led to optimum ionic conductivity owing tolong range order
Zhang, Yan. "SURFACE AND STRUCTURAL MODIFICATION OF CARBON ELECTRODES FOR ELECTROANALYSIS AND ELECTROCHEMICAL CONVERSION." UKnowledge, 2018. https://uknowledge.uky.edu/chemistry_etds/96.
Повний текст джерелаZhao, Jinhui. "Novel Nano-catalysts for Sustainable Processes." Thesis, The University of Sydney, 2019. https://hdl.handle.net/2123/21523.
Повний текст джерелаO'Connor, Timothy F. III. "Synthesis and Dynamics of Photocatalytic Type-II ZnSe/CdS/Pt Metal-Semiconductor Heteronanostructures." Bowling Green State University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1340038781.
Повний текст джерелаWang, Lizhuo. "Nano Catalyst Design and Application in Sustainable Chemistry." Thesis, The University of Sydney, 2022. https://hdl.handle.net/2123/29570.
Повний текст джерелаDüskünkorur, Hale. "Biopolyester synthesis by enzymatic catalysis and development of nanohybrid systems." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00864276.
Повний текст джерелаDole, Holly. "Connecting Metal-Support Interaction and Electrochemical Promotion Phenomena for Nano-structured Catalysts." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34610.
Повний текст джерелаYou, Sheng Mu. "Metal organic frameworks as efficient photosensitizer for TiO₂ nanoarray anode and application to water splitting in PEC cells Fe/Ni Bimetallic organic framework deposited on TiO₂ nanotube array for enhancing higher and stable activity of oxygen evolution reaction Novel nano-architectured water splitting photoanodes based on TiO₂-nanorod mats surface sensitized by ZIF-67 coatings Surface sensitization of TiO₂ nanorod mats by electrodeposition of ZIF-67 for water photo-oxidation Electrochemically capacitive deionization of copper (II) using 3D hierarchically reduced graphene oxide architectures." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASF015.
Повний текст джерелаThe fossil fuel reserves are dwindling and their unrestricted use has generated profound changes in Earth's surface temperature and climate. Storing solar energy in the form of hydrogen produced by dissociation of water is an ideal way to mitigate global warming. Materials from the “metal organic framework” (MOF) family are starting to be used as photo-electrocatalysts, especially for photo-dissociation of water. Their extremely high porosity and their great versatility, both chemical and structural, designate them as potential candidates to facilitate the absorption of solar radiation and catalyze the dissociation of water in photoelectrochemical cells. By controlling the chemical composition and doping of the linker used in the MOF, it is possible to adjust the band gap energy, to favor the functionalization on very varied substrates or even to adjust their resistance to corrosion in various chemical environments. They are therefore materials of great interest for catalysis, electrocatalysis or photo-electro-catalysis. On the other hand, nano-structured TiO₂, for example in the form of nanotube or nanowire mats, sometimes called TiO₂ nanoarray (TNA), is a material very suitable for the construction of photoanodes for the evolution of oxygen in aqueous medium. It has already been extensively studied and described in the literature. During our thesis, we manufactured composite materials made up of MOFs of transition metals (Ni, Co, Fe) deposited on TNA (network of nanotubes or nanowires). For this we used an electrochemical method of electrodeposition (cyclic voltammetry). This allowed us to deposit metallic nanoparticles on TNA with fixed potential - 1.0 V and then transform them by chemical reaction with organic ligands (1,3,5-benzenetricarboxylic acid, BTC, 1,4-benzenedicarboxylic acid, BDC and imidazole, 2MZ) by thermal-thermal route. The materials obtained exhibit significant electrocatalytic activity and excellent photoelectrochemical durability. These composite materials have been successfully used as an active phase in photo-electrodes for the oxygen release reaction (OER)
PRADA, STEFANO. "Enhancing oxide surface reactivity by doping or nano-structuring." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2014. http://hdl.handle.net/10281/50011.
Повний текст джерелаBelarbi, Hichem. "Élaboration des zéolithes nano-structurées M-ZSM-5 (M=Cu, Cr et Fe) : Etude comparée des solides poreux minéraux et organométalliques MOFs dans l’oxydation de méthylènes benzyliques." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20192.
Повний текст джерелаEnergy, sustainable development, and health are at the heart of contemporary concerns of the planet. The inevitable disappearance of fossil fuels, the severe consequences of carbon emissions on the environment and health require quick and effective solutions to supplement the first and minimize others. Among the solutions proposed, there are porous materials which have proven their effectiveness; however, there are still obstacles to be corrected or circumvented. In this thesis, we focus on the problem of bulky molecules' inaccessibility in micro pores of the materials we wish to study. In the first part, we optimize the material in this case, ZSM-5, with a reduction in particle size to a microscopic scale to another nano, which allows us to increase the external surface after changing certain parameters. In the second step, in order to give a catalytic entity to our support (zeolite), we activate with this material incorporating cations selected according to a specific property of the benzyl methylenes oxidation reaction. For this reason we developed different method of preparation. We conclude this thesis by catalysis with M-ZSM-5 (M = Cu, Cr and Fe) and a comparative study on the method of preparation and the MOFs that bears the same cations as mineral part which constitutes the materials
Panaritis, Christopher. "Metal-Support Interaction and Electrochemical Promotion of Nano-Structured Catalysts for the Reverse Water Gas Shift Reaction." Thesis, Université d'Ottawa / University of Ottawa, 2021. http://hdl.handle.net/10393/41963.
Повний текст джерелаM'Nasri, Najib. "Elaboration de nanomatériaux composites métal@nanoparticules de silice mésoporeuses (MSN) : étude des performances catalytiques en phase aqueuse et des propriétés d'adsorption sélective du diiode en phase gaz." Thesis, Montpellier 2, 2014. http://www.theses.fr/2014MON20199.
Повний текст джерелаThe objective of this thesis was to develop efficient synthesis routes to prepare mesoporous silica-based nano-sized particles, designated as MSN, with controllable morphology and derivatised with selected transition metals. One-pot preparation and surface functionalisation procedures based on the insertion of the metal-phase precursor into the porogen aggregates were thoroughly optimised leading to silica particles containing such single metals as copper, palladium, platinum, silver or gold, as well as a two-metal phase of copper and palladium or that of palladium and platinum. It was demonstrated that the highly dispersed metal phase was localised on the pore surface and therefore it was readily accessible to the target chemicals on which to base the catalytic performance of the resulting materials. Among others, the remarkable catalytic performance of the Cu@MSN material in Huisgen and Sonogashira reactions and its propensity to undergo efficient recycling were proven through laboratory-scale testing. Experimental study of the selective adsorption of iodine vapour onto MSN supports functionalised with silver nanoparticles indicated an excellent retention capacity of such materials
Genuzio, Francesca. "Spectro-microscopic investigation of Fe-oxide based model catalysts and instrumental development." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2016. http://dx.doi.org/10.18452/17526.
Повний текст джерелаThis work presents the investigation of Fe-oxide systems, combining microscopy (LEEM, X-PEEM), diffraction (LEED) and spectroscopy (XPS), and the electron-optical development of adaptive optics and aberration corrections for an electrostatic imaging energy analyzer. Experimentally, we studied magnetite (Fe3O4) and hematite (α-Fe2O3) thin films. Their crystal structure, stoichiometry as well as their surface termination can be tuned by special preparation procedures. Taking advantage of real time observation with microscopy, diffraction and spectroscopy, we investigated (a) the surface modifications of Fe3O4 and α-Fe2O3 thin films by Fe deposition; (b) the reversible phase transformation Fe3O4 ↔ α-Fe2O3 under different oxidation conditions; (c) the formation of the metastable γ-Fe2O3 phase and (d) the interaction of Fe3O4 and α-Fe2O3 surfaces with supported Pt nanoparticles . An algorithm was developed to simulate the LEEM image contrast for inhomogeneous 2D surfaces. The possible application to experimental data and the limitation will be discussed. Finally, the design of an energy filtering system is presented, which will be implemented in a new generation PEEM/LEEM microscope. The system bases on the same imaging principle as the magnetic Ω-filter, successfully implemented in the actual SMART microscope. The new instrument aims for the improvement of lateral and energy resolution in X-PEEM (5 nm and 70 meV, respectively). The majority of the possible second order aberrations are self-compensated by intrinsic symmetry. The effect of the other aberrations is reduced by an adequate design for the deceleration-acceleration optics in combination with optimized pass energy. Furthermore, additional hexapole multipoles compensate for the residual dominating aberrations, yielding in the lateral resolution and energy resolution better than 2 nm and 75 meV, respectively.
Kane, Kenneth. "Metallic systems at the nano and micro scale: Bimetallic nanoparticles as catalysts and MCrAlY bond coats in thermal barrier coatings." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/5732.
Повний текст джерелаBordet, Alexis. "Une nouvelle génération de nano-catalyseurs à base de carbure de fer pour le stockage chimique de l'énergie." Thesis, Toulouse, INSA, 2016. http://www.theses.fr/2016ISAT0017/document.
Повний текст джерелаAfter several decades of oblivious fossil resources consumption, humanity is now facing major issues regarding global warming and energy production and storage. In the double context of intermittent renewable energy storage and CO2 recovery, the power-to-gas approach, and especially the Sabatier reaction (catalytic hydrogenation of carbon dioxide to methane + water) is of special interest. The main goal of this thesis is to perform the Sabatier reaction using magnetically activated nano-catalysts. The use of magnetic nanoparticles to convert electromagnetic energy into heat is indeed an approach of growing interest in catalysis, even if the field of biomedicine obviously concentrate most of the applications (magnetic hyperthermia, drug delivery, etc.). In this respect, the interest of the synthesized nanoparticles for biomedical applications is studied and discussed. We describe herein a pathway to iron carbide nanoparticles allowing a fine tuning of their carbon content and magnetic properties. We show that the carbon content and the crystallinity of the synthesized nanoparticles greatly impact their magnetic heating efficiency. The Fe2.2C crystallographic phase especially appears to be the key to highly enhanced specific absorption rates (SARs). We took advantage of these exceptional heating properties to investigate the Sabatier reaction in a continuous flow reactor, the catalyst being activated through magnetic induction. The SAR of synthesized iron carbide nanoparticles appeared to be sufficient to reach the temperature required for the activation of the Sabatier reaction (typically > 250°C), and promising results were obtained in a continuous flow reactor. We were thus able to demonstrate that the concept of magnetically induced catalysis can be successfully applied to the CO2 methanation reaction and represents an approach of strategic interest in the double context of intermittent energy storage and CO2 valorization
Koneti, Siddardha. "In situ and 3D environmental transmission electron microscopy of Pd-Al2O3 nano catalysts : Fast tomography with applications to other catalytic systems in operando conditions and to electron beam sensitive nanomaterials." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEI123/document.
Повний текст джерелаIn the beginning of the XXIst century, Environmental Transmission Electron Microscopy has become one of the reliable characterization techniques of nanomaterials in conditions mimicking their real life. ETEM is now able to follow the dynamic evolution of nanomaterials under various conditions like high temperature, liquid or various gas pressures. Among various fields of research, catalysis can benefit significantly from Environmental Microscopy. This contribution starts with the study of the Palladium-Alumina catalytic system. Pd nanoparticles supported by α-Al2O3 and δ-Al2O3 are of an important physicochemical and environmental interest, particularly in the field of selective hydrogenation in petrochemistry, for the synthesis of polymers or CO2 hydrogenation for methane production. We first performed 2D analyses at different steps of the synthesis process, then the same synthesis steps were performed under in situ conditions. The motivation of this approach was to compare post mortem treatments with ETEM observations. In general, 2D data provide limited insights on, for example, the morphology and position of supported nanoparticles. We have then developed a new fast acquisition approach to collect tomographic tilt series in very short times, enabling to reconstruct nano-systems in 3D during their dynamical evolution. Taking advantage of this approach, we have determined the activation energy for soot combustion on YSZ oxidation catalysts for diesel motors from volumetric data extracted from in situ experiments. Fast electron tomography was also applied to electron beam sensitive materials, like polymer nanocomposites and biological materials, showing the wide spectrum of possible applications for rapid 3D characterization of nanomaterials
Nowakowski, Pawel. "Systèmes micro-nano-structurés et couches minces multifonctionnels, à base de dioxyde de ruthénium : élaborations et propriétés catalytiques et électriques." Phd thesis, Université du Sud Toulon Var, 2008. http://tel.archives-ouvertes.fr/tel-00343499.
Повний текст джерелаNguyen, Tao-Nhân V. "Theoretical studies of solvation and catalysis : clusters as chemical nano-reactors." Thesis, 2005. http://spectrum.library.concordia.ca/8643/1/NR09951.pdf.
Повний текст джерелаLin, Jiunn-Nan, and 林俊男. "Development of Supported Gold Nano-Particles and Their Applications in Combustion Catalysis." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/53122831542945342811.
Повний текст джерела國立臺灣大學
化學工程學研究所
90
The development of highly active supported gold nano-particles for catalysis application was studied in this dissertation. The effects of supports, surface acidity modification, and gold solution on the supported gold nano-particles were investigated. The characterization of the catalysts, the examination of catalytic activities, and the discussion of the effects of preparation conditions were presented. The mechanisms of gold loading were also built. It was found that the catalytic activity of supported gold nano-particles was related to the dispersion, supports, and preparation conditions, which control the sizes of the gold particles on selected supports. For zeolites as supports, it was found that the gold loading didn’t depend on the IEPs of the the zeolites and was related to the structures and the amount of ion-exchange sites of the zeolites. It was also found that the protons in zeolites can catalyze the condensation of gold precursors to form the larger gold particles. Thus, decreasing the amount of protons in zeolites before loading gold was effective to prepare highly active Au/zeolite catalysts for low temperature CO oxidation. The gold particles on acidity modified Y-type zeolite were 2.5 times more active and stable than those on proton-rich Y-type zeolite for CO oxidation at 0℃. From the TEM results, it was found that most of the gold particles on the acidity modified Y-type zeolite were smaller than 2nm and were more uniformly dispersed. The catalytic activities and stability of Au/zeolites for CO oxidation were also affected by the structures of the zeolites and Au/Y catalyst was the best among them.. From the study of gold precursors in the solution, it was found that different species and sizes of gold precursors were formed in the solution at different preparation conditions, which affected the gold particle sizes and catalytic activity. The gold precursors were affected by the gold concentrations, pH values, preparation temperature, and time. Therefore, it was concluded from this research that for the preparation of Au/Y with high CO oxidation activity, a gold solution with surface acidity modified Y-type zeolite (1 g of zeolite per 125 ml solution) and with initial gold concentration around 1.46×10-3 M, solution pH at 6, a solution temperature around 80 ℃ and stirring for 1h were recommended. γ-Al2O3, SiO2 and TiO2 were also used as supports to investigate the effects of these oxides on the preparation of gold catalysts. Forγ-Al2O3 and SiO2, it was found that the mechanism of gold loading was via electrostatic deposition, which depended on the IEPs of the supports. It was observed that the gold particles supported onγ-Al2O3 and SiO2 from gold solutions with pH value of 6.0 were not active for CO oxidation at 0℃. High temperature reduction was needed to activate these supported gold particles for CO oxidation. This was due to the formation of large gold particles and small gold particles with residual chlorides on the supports. Different fromγ-Al2O3 and SiO2, the mechanism of gold loading on TiO2 was via adsorption-reduction model, which resulted in higher gold loading and less residual chlorides. Thus, the Au/TiO2 were very active for CO oxidation as Au/Y at 0℃. It was inevitable to have an inlet gas stream with moisture for the application of CO oxidation. It was found that moisture showed little effect on CO oxidation over as-prepared Au/TiO2 catalysts; however, the catalytic activity of as-prepared Au/Y can be enhanced over 20% of CO conversion by the presence of water vapor. The activity of Au/Y was superior to that of Au/TiO2 in wet reaction conditions. In addition to the application for low temperature CO oxidation, Au/Cr/γ-Al2O3 was also prepared in this study to test the complete oxidation of C3H8 for the application in VOCs removal and compared with Cr/γ-Al2O3. It was found that the oxidation of C3H8 over Cr/γ-Al2O3 was via reduction-oxidation mechanism, which was also named as Mar-van Krevelen mechanism, and the existence of gold can increase the reduction-oxidation rate, therefore, the activity of Cr/γ-Al2O3 was enhanced by gold. However, the catalytic activity of Au/Cr/γ-Al2O3 decayed during reaction. After the regeneration process, the activity of Au/Cr/γ-Al2O3 couldn’t be recovered to its initial conversion. The deactivation was the formation of coke and the gold particles sintered during reaction and/or the regeneration process. According to these research results, Au/Y catalyst prepared in this study can be as active and stable as Au/TiO2 at 0℃ for CO oxidation. Moreover, the presence of 3 % water vapor in the feed stream can enhance the catalytic activity of Au/Y and the performance was even superior to Au/TiO2 at 25℃. Furthermore, gold particles were not capable of high temperature catalytic reaction in the view of application because the gold particles sintered more easily. It was suggested that it was better to make use of these supported gold nano-particles in catalysis at lower temperature, such as the removal of CO from our surroundings at room temperature.
Roy, Sounak. "Noble Metal And Base Metal Ion Substituted Ceo2 And Tio2 : Efficient Catalysts For Nox Abatement." Thesis, 2007. http://hdl.handle.net/2005/584.
Повний текст джерелаBarrett, Dean Howard. "A stable high temperature gold nano-catalyst: synthesis, characterization and application." Thesis, 2013. http://hdl.handle.net/10539/12346.
Повний текст джерелаShodiya, Titilayo. "Utilization of Nano-Catalysts for Green Electric Power Generation." Diss., 2015. http://hdl.handle.net/10161/9817.
Повний текст джерелаNano-structures were investigated for the advancement of energy conversion technology because of their enhanced catalytic, thermal, and physiochemical interfacial properties and increased solar absorption. Hydrogen is a widely investigated and proven fuel and energy carrier for promising "green" technologies such as fuel cells. Difficulties involving storage, transport, and availability remain challenges that inhibit the widespread use of hydrogen fuel. For these reasons, in-situ hydrogen production has been at the forefront of research in the renewable and sustainable energy field. A common approach for hydrogen generation is the reforming of alcoholic and hydrocarbon fuels from fossil and renewable sources to a hydrogen-rich gas mixture.
Unfortunately, an intrinsic byproduct of any fuel reforming reaction is toxic and highly reactive CO, which has to be removed before the hydrogen gas can be used in fuel cells or delicate chemical processes. In this work, Au/alpha-Fe2O3 catalyst was synthesized using a modified co-precipitation method to generate an inverse catalyst model. The effects of introducing CO2 and H2O during preferential oxidation (PROX) of CO were investigated. For realistic conditions of (bio-)fuel reforming, 24% CO2 and 10% water the highest document conversion, 99.85% was achieved. The mechanism for PROX is not known definitively, however, current literature believes the gold particle size is the key. In contrast, we emphasize the tremendous role of the support particle size. A particle size study was performed to have in depth analysis of the catalysts morphology during synthesis. With this study we were also able to modify how the catalyst was made to further reduce the particle size of the support material leading to ~99.9% conversion. We also showed that the resulting PROX output gas could power a PEM fuel cell with only a 4% drop in power without poisoning the membrane electrode assembly.
The second major aim of this study is to develop an energy-efficient technology that fuses photothermal catalysis and plasmonic phenomena. Although current literature has claimed that the coupling of these technologies is impossible, here we demonstrate the fabrication of reaction cells for plasmon-induced photo-catalytic hydrogen production. The localized nature of the plasmon resonance allows the entire system to remain at ambient temperatures while a high-temperature methanol reformation reaction occurs at the plasmonic sites. Employing a nanostructured plasmonic substrate, we have successfully achieved sufficient thermal excitement (via localized surface plasmon resonance (LSPR)) to facilitate a heterogeneous chemical reaction. The experimental tests demonstrate that hydrogen gas can indeed be generated in a cold reactor, which has never been done before. Additionally, the proposed method has the highest solar absorption out of several variations and significantly reduces the cost, while increasing the efficiency of solar fuels.
Dissertation
Ruderman, Andrés. "Electrocatálisis en electrodos nano estructurados de plata." Doctoral thesis, 2016. http://hdl.handle.net/11086/5468.
Повний текст джерелаLos estudios realizados en este trabajo abarcan diferentes aspectos de la cinética de la reacción de desprendimiento de hidrógeno (her). Esto tiene como finalidad la obtención de nuevos conocimientos que permitan comprender la actividad electrocatalítica en diversas superficies monocristalinas de plata. De esta manera, las investigaciones realizadas se enmarcan en la búsqueda de un catalizador eficiente y a un costo razonable para la her. El trabajo desarrollado se divide en dos áreas: comprender la cinética de la her en diferentes superficies monocristalinas escalonadas de Ag(11n) y estudiar el mecanismo de deposición de Rh sobre Ag, el cuál puede ser un electrocatalizador bimetálico eficiente para la her.
"The Effects of Different Particle Size of Nano-ZnO and Alumina-based Catalysts on Removal of Atrazine from Water with Ozone." Thesis, 2015. http://hdl.handle.net/10388/ETD-2015-12-2380.
Повний текст джерелаGoislard, De Monsabert Thomas. "Couches de Nanotubes et Filaments de Carbone pour l'Emission Froide d'Electrons -Intégration aux Ecrans Plats à Emission de Champ." Phd thesis, 2006. http://tel.archives-ouvertes.fr/tel-00090016.
Повний текст джерелаLes paramètres clés, avantages et limitations de plusieurs techniques de préparation et d'intégration de nano particules catalytiques ont d'abord été analysés : le démouillage d'un film continu, la gravure humide post-démouillage, le dépôt de nano agrégats et la lithographie électronique. Trois techniques de croissance de couches carbonées ont ensuite été étudiées dans le même réacteur : la CVD thermique simple, la CVD en présence d'un champ électrique et la CVD avec assistance plasma à partir d'une source de carbone solide. Enfin, les propriétés émissives des diverses couches carbonées élaborées ont été mesurées, en mode diode pour les couches synthétisées sur échantillon plan et en mode triode pour les couches intégrées sur structure cathodique d'écran.
L'analyse de ces résultats a permis de clarifier les liens entre paramètres technologiques d'élaboration, morphologie et performances émissives des films de nanotubes et filaments de carbone.