Dissertations / Theses on the topic 'Hydrogen'
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Samanta, C. "Direct oxidation of hydrogen to hydrogen peroxide." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2004. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2423.
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Östersjö, Victor. "Supersymmetry for the Hydrogen Atom." Thesis, Karlstads universitet, Institutionen för ingenjörsvetenskap och fysik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-35397.
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In this thesis it will be shown that the hydrogen atom has a SU(2) × SU(2) symmetry generated by the quantum mechanical angular momentum and Runge-Lenz vector operators. Additionally, the hydrogenic atom will be studied with supersymmetric methods to identify a supersymmetry that relates different such systems. This thesis is intended to present the material in a manner accessible to people without background in Lie groups and supersymmetry, as well as fill in some calculations between steps that are not spelt out in the litterature.
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Schmidtmann, Marc. "Hydrogen transfer in hydrogen bonded solid state materials." Thesis, Connect to e-thesis, 2008. http://theses.gla.ac.uk/284/.
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Thesis (Ph.D.) - University of Glasgow, 2008.Ph.D. thesis submitted to the Department of Chemistry, Faculty of Physical Sciences, University of Glasgow, 2008. Includes bibliographical references. Print version also available.
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Stapf, Stefanie [Verfasser], Nicolas [Gutachter] Plumeré, and Wolfgang [Gutachter] Schuhmann. "Viologen polymers for reversible hydrogen oxidation and hydrogen generation in redox hydrogels / Stefanie Stapf ; Gutachter: Nicolas Plumeré, Wolfgang Schuhmann." Bochum : Ruhr-Universität Bochum, 2017. http://d-nb.info/1144614406/34.
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Whittaker, Alexander. "Hydrogen future." Thesis, Blekinge Tekniska Högskola, Institutionen för tillämpad signalbehandling, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-10420.
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Hydrogen electrolysis has gone through a number of stages in research and applications. From what we can see from this report, there are several ways of producing hydrogen electrolysis, and several applications. The main purposes of this report however, is not to describe what hydrogen electrolysis is and its applications. Research and experiments has already proven that it is a functioning technology. The aim is to gather the necessary information, both theoretically and practically to be able, from a technical and business point of view analyze if this in fact is a realistic solution. To maintain a system of sustainable energy has always been an attractive market and there has existed a number of technologies that has had their share of the fame. However, most of these solutions have shown not to be viable, lucrative or technically scalable. Hence, the important issue to address is whether this is a solution worth investing in. The information gathered for the theory is based on technical reports, academic scripture and literature. All of which can be back tracked to its original source. The practical test is done by using a test kit made for universities and other institutes to better understand how hydrogen electrolysis works. The materials used are all scientifically acceptable according to the theories and technologies surrounding hydrogen electrolysis. Hence, the data gathered from the test kits are all accurate according to current research.
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Кравченко, Наталія Олександрівна, Наталия Александровна Кравченко, Nataliia Oleksandrivna Kravchenko, and R. Lopatka. "Hydrogen Energy." Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/13492.
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Hydrogen is the simplest element. An atom of hydrogen consists of only one proton and one electron. It's also the most plentiful element in the universe. Despite its simplicity and abundance, hydrogen doesn't occur naturally as a gas on the Earth - it's always combined with other elements. Water, for example, is a combination of hydrogen and oxygen (H2O).
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Lusson, Salomé. "Hydrogen liquefaction chain: co-product hydrogen and upstream study." Thesis, KTH, Kemiteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-290940.
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The European Green Deal declared that Europe must decarbonize to become carbon-neutral within 2050. To do so, the European Parliament emphasized hydrogen as a major tool for energy transition. In regard of current environmental challenges, liquid hydrogen has raised interest as energy carrier for energy storage and transport. Due to growing use of renewable energy sources such as solar and wind energy, intermittent sources will increase. Hydrogen production methods will become mostly intermittent with renewable energies. However, due to historical hydrogen production by steam methane reforming, liquefaction was developed at steady nominal charge. In order to feed current liquefaction processes with renewable hydrogen, a buffer system will become required. This thesis studies the effect of buffer and liquefaction combination on performances and cost. In order to carry out this liquefaction from intermittent source, the study is performed based on industrial data from a variable co-product hydrogen profile. This profile acts as a simplified case. The scope of the study is drawn by considering compressed hydrogen as temporary storage for the buffer while liquefaction unit is modelled around Linde Leuna cycle. The technical-economical study covers sensitivity analysis on both buffer and liquefaction unit. For the buffer unit, storage capacity, storage pressure, liquefaction flexibility and recuperation rate impacts are examined. Liquefaction sensitivity analysis includes pressure drop, electricity cost and capacity study. It is highlighted that 100% gaseous hydrogen recovery is not profitable due to high costs increase for recuperation higher than 95%. Storage pressure and capacity as well as liquefaction flexibility drive buffer cost and recuperation rate of the co-product hydrogen. Considering liquefaction study, results highlight that pressure drops cause first order deviations in energy consumption as well as on cost. Results show that the specific buffer cost is evaluated between 71% and 59% of liquefaction cost. Hence the thesis raises attention on future work on heat exchangers design, pressure drop optimization and liquefaction unit flexibility to allow an optimized renewable liquid hydrogen production.
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Chen, Guo Fu. "The diffusion of muonic hydrogen atoms in hydrogen gas." W&M ScholarWorks, 1990. https://scholarworks.wm.edu/etd/1539623790.
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This experiment measured the time distribution of muonic hydrogen atoms which were formed when negative muons were brought to rest in H{dollar}\sb2{dollar} gas, containing Au target foils, at five pressures (750 mbar, 375 mbar, 188 mbar, 94 mbar and 47 mbar at 4.6 mm foil spacing). A Monte Carlo method is applied for deducing the initial velocity distribution, and preliminary results are obtained. The initial velocity distribution of {dollar}\mu{dollar}H atoms is reasonably well described as a 'Maxwellian' velocity distribution with a mean energy E = 3.4 eV. The corresponding muon mean capture energy is obtained: E{dollar}\sb{lcub}\rm c{rcub}{dollar} {dollar}\approx{dollar} 34 eV for {dollar}\mu{dollar}H atom and E{dollar}\sb{lcub}\rm c{rcub}{dollar} {dollar}\approx{dollar} 68 eV for {dollar}\mu{dollar}H{dollar}\sb2{dollar} molecules. We also find the negative muon capture energy distribution is exponential.;In addition, a significant improvement of the negative muon mean life {dollar}\tau{dollar} in Au is abtained in this experiment.: {dollar}\tau\sb{lcub}\rm Au{rcub}{dollar} = 69.716 {dollar}\pm{dollar} 0.144 ns. The "full decay curve fitting method" which we use in this experiment has an advantage over the previous method in three aspects: (1) We have measured the mean life and determined the time resolution {dollar}\sigma{dollar}(E) of a detector at a particular energy level; (2) We have determined the effective zero time of the decay curve; (3) We have provided a possible way to measure the mean life {dollar}\tau{dollar} when {dollar}\tau{dollar} is less than the time resolution {dollar}\sigma{dollar}(E) of the detector ({dollar}\tau{dollar} {dollar}<{dollar} {dollar}\sigma{dollar}(E)).
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Castillo, Moreno Patricia. "Développement d'un procédé de production d'hydrogène photofermentaire à partir de lactosérum." Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI029/document.
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L'hydrogène est une source d'énergie précieuse en tant que source d'énergie propre et que matière première pour des innombrables industries.Les procédés biologiques de production d'hydrogène gagnent en importance en raison de leurs avantages opérationnelles et de leur polyvalence dans les substrats utilisés (y compris les eaux usées).Dans cette thèse doctoral, on a développé une méthodologie photo-fermentative de production d'hydrogène en utilisant du lactosérum en tant que substrat pour la bactérie Rhodobacter capsulatus IR3::LacZ et B10::LacZ.Ce projet a été réalisé en trois étapes, exposées dans les différents chapitres.Dans la première étape on a identifié les facteurs pertinents pour la production de l'hydrogène avec du sérum synthétique en utilisant la méthodologie de plan d'expériences.Les résultats de cet étape on a obtenu quatre modèles statistiques et on a choisi la souche IR3::LacZ pour les expériences avec du lactosérum industriel.Le rendement volumétrique maximal et le rendement produit / substrat Y P/S obtenus pour la première étape ont été de 64 ml h-1L-1 et 2,08 mol H2 mol-1 C (“C” représente la source de carbone dans ce cas lactose et lactate) pour la solution amortissant le phosphate et 43.01 ml h-1L-1 y 2.52 mol H2 mol-1 C pour la solution Kolthoff.Dans la deuxième étape, on a évalué la production d'hydrogène avec du lactosérum industriel. On a appliqué un pré-traitement de trois étapes avant d'utiliser le lactosérum comme substrat : réduction du contenu gras, déprotéinisation et stérilisation. On a obtenu un modèle validé qui décrit la production d'hydrogène seulement pour la solution amortissant de phosphate. Le rendement volumétrique maximal et le YP/S ont été de 45.93 ml h-1L-1 et de 2.29 mol H2 mol-1 C respectivement. On a déterminé que l'addition d'une étape d’homo-fermentation au processus de prétraitement es avantageuse au rendement du processus. On a obtenu une productivité volumétrique de 69.71 ml h-1L-1 et de YP/S de 2.96 mol H2 mol-1 CLa troisième étape a été la mise à l'échelle des expériences à réacteurs de 1,5 L pour sérum synthétique et de 1L pour serum industriel. On a décelé de la contamination dû à la présence d'un processus de fermentation, lequel a généré une haute production de biogas composé exclusivement par H2 y CO2 ce dernier dans une concentration non superieur à 30% (v/v).Pour ces raisons, on a conclu que conclu que le processus de production intégré, en couplant la fermentation obscure et la photo-fermentation est une option avec un énorme potentiel pour l'utilisation de lactosérum comme substrat dans la production d'hydrogèneHydrogen is a valuable gas use as a clean energy source and feedstock for some industries. Biological hydrogen production processes are gaining importance due to their operational conditions and versatility in the substrates (including wastewater). A hydrogen production photo fermentative methodology was developed using cheese whey as a substrate for the bacteria Rhodobacter capsulatus strain IR3::LacZ and B10::LacZ . The project was carried out in three stages.The purpose of the first stage is to identify the relevant factors to produce hydrogen for a synthetic whey medium in a photofermentation process, using the Design of Experiments methodology. The products of this stage are four statistical models, obtained for each strain and buffer solution studied. The strain IR3::LacZ was selected for the experiments with industrial whey as substrate. The maximum volumetric yield and the product/substrate yield YP/S were 64 ml h-1L-1 and 2.08 mol H2 mol-1 C (C is the carbon source in this case lactose and lactate) and 43.01 ml h-1L-1 and 2.52 mol H2 mol-1 C for phosphate buffer and Kolthoff buffer, respectively.In the second stage the production of hydrogen with industrial whey was evaluated. A three-step pre-treatment was applied before using industrial cheese whey as substrate: fat reduction, deproteinization and sterilization. A validate statistical model describing hydrogen production was only obtained for phosphate buffer. The maximum volumetric yield and the product/substrate yield YP/S were 45.93 ml h-1L-1 and 2.29 mol H2 mol-1 C respectively. The addition of an homofermentation to the pretreatment improved the production yield, in this case a volumetric productivity of 69.71 ml h-1L-1 and a YP/S of 2.96 mol H2 mol-1 C were obtained.The third stage was the scale-up to 1.5 and 1 reactor L for synthetic whey and 1L for synthetic and industrial whey respectively. A fermentative process appeared due to a bacterial contamination, leading to a high biogas production. Biogas was exclusively composed of H2 and CO2 the last in a concentration not exceeding 30% (v/v). For this reason, it was concluded that the integrated production process coupling dark and photo fermentations) is an option with great potential for the use of whey as substrate in the production of hydrogen
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Pătru, Alexandra. "Développement de catalyseurs pour un électrolyseur alcalin H2/O2." Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20012.
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Le travail de thèse présenté dans ce mémoire, est consacré à l'étude des nouveaux matériaux d'électrodes pour l'électrolyse de l'eau en milieu alcalin. L'objectif de ces études est de développer de nouveaux électrocatalyseurs à base de métaux non nobles, capables d'améliorer les cinétiques de réactions intervenant dans la décomposition de l'eau : l'évolution de l'hydrogène (HER) et l'évolution de l'oxygène (OER). L'amélioration des performances catalytiques se traduit par une diminution des surtensions de réaction et donc de l'énergie nécessaire à la production de l'hydrogène. Pour cela, nous avons choisir de réaliser des électrodes à base de nanoparticules de nickel et de cobalt pour l'HER et de nanoparticules de cobaltites de cobalt, Co3O4, pour l'OER. La mise au point de plusieurs méthodes innovantes de formulation des électrodes (dépôt par électrophorèse « réactive » et électrodes composites à base liant organique fonctionnel) a permis la réduction des surtensions des réactions. Pour une densité de courant de 100 mA cm-2, une surtension cathodique de -286 mV est nécessaire avec les électrodes composites à base de nanoparticules de nickel, -238 mV pour une électrode en Co obtenue par électrophorèse et une surtension anodique 323 mV pour une électrode composite à base de nanoparticules de Co3O4. Une étude électrochimique approfondie de l'HER a été réalisée sur différentes morphologies de nanoparticules de nickelThe PhD work, presented in this manuscript, is devoted to the study of new electrode materials for alkaline water electrolysis.The aim of this study is to develop new electrocatalysts based on non-noble metals. These catalysts are designed to improve the kinetics of the reactions involved in the water splitting: hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The improvement of catalytic reaction results in the decrease of the overpotentials and therefore the saving of energy needed for hydrogen production. To do that, nickel and cobalt nanoparticles were used for HER, and Co3O4 nanoparticles for OER. The development of several innovative methods for electrode formulation (deposition by electrophoresis and composites electrodes based on a functional organic binder) reduced the overpotential reactions. For a current density of 100 mA cm-2, -286 mV of cathodic overpotential is needed for composites electrodes based on nickel nanoparticles, -238 mV for a Co-based electrode made by electrophoresis and 323 mV of anodic overpotential for a Co3O4 -based composite electrode. A detailed electrochemical study was made for HER on various morphologies of nickel nanoparticles
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Riley, Duncan John. "First principles simulations of hydrogen-bonded and hydrogen storage systems." Thesis, University of Salford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.490280.
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CORDARO, RICHARD BRIAN. "ELECTRON IMPACT DISSOCIATIVE IONIZATION OF HYDROGEN, WATER, AND HYDROGEN SULFIDE." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188028.
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The dissociative ionization by electron impact of H₂, H₂O, and H₂S was investigated between the electron impact energies of 20 and 45 eV. Protons were the detected fragments, and a time-of-flight method was used to measure the proton kinetic energies. By also measuring the thresholds for the production of discrete energy groups of protons, it was possible to determine the dissociation limits and kinetic energy distributions for individual electronic states. It was found that autoionizing states that lead to dissociation were the major contributors of proton fragments for all of the molecules investigated. Some of the measurements are tabulated in the following table. (UNFORMATTED TABLE FOLLOWS) Molecule Threshold Dissociation Probable Probable (eV) limit (eV) state fragments H₂ 24.5±1.0 18.0±1.0 Q₁ ¹Σ(g)⁺ H⁺, H(1S) 30.5±1.0 18.0±1.0 Q₁ ¹Πᵤ H⁺, H(1S) 36.5±1.0 -- ²Πᵤ H⁺, H(2P) H₂O 24.5±1.0 19.5±1.0 -- H⁺, OH (X²Π) 29.5±1.0 23.0±1.0 -- H⁺,O(³P),H(1S) H₂S 25.5±1.0 18.0±1.0 -- H⁺, HS (X²Π) 32.0±1.0 -- -- H⁺, . . . 42.0±1.0 -- -- H⁺, . . . (TABLE ENDS)
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Buan, Marthe Emelie Melandsø. "Photoelectrochemical Hydrogen Production." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for materialteknologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19101.
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The possibilities for using CaNb2O6 as a photocatalyst in direct water splitting have been evaluated by investigating the electronic structure of the material. In addition the oxide was doped with nitrogen in order to modify the electronic structure and obtain visible light absorption. Experimental techniques such as electrochemical impedance spectroscopy (EIS), photocurrent, and diffuse reflectance spectroscopy (DRS) were combined with theoretical approaches to determine the bandgap, flatband potential and quasi-Fermi levels of the photocatalyst. CaNb2O6 was prepared by a sol-gel synthesis and doped with nitrogen by heat treatment of the oxide powder in an ammonia atmosphere. X-ray diffraction (XRD) confirmed phase pure orthorhombic CaNb2O6 for both pure and N-doped oxide and excluded a possible transformation of the oxide into an oxynitride. Upon illumination anodic photocurrents were observed implying that CaNb2O6 was an n-type semiconductor due to oxygen vacancies in the lattice. From the wavelength dependency of the photocurrent a direct bandgap of 3.7eV and an indirect bandgap of 3.4eV were determined for undoped CaNb2O6. Doping with nitrogen altered the optical properties of the oxide and shifted the absorption edge into the visible light region. Calculations using the density functional theory (DFT) attributed the change in absorption properties to the formation of narrow energy bands above the valence band of pure CaNb2O6. An alternative explanation could be a hybridization of N 2p and O 2p bands. Correspondingly a reduction of the bandgaps for N-doped CaNb2O6 with respect to the undoped oxide was identified. Impedance was applied to determine the flatband potential of CaNb2O6 from Mott-Schottky plots. However the obtained results seemed to be dominated by contributions from the electrode substrate. Theoretical investigations concluded that pinhole-free oxide layers creating an ohmic contact with the substrate are required in order to designate the observed impedance response to the space charge capacitance. Quasi-Fermi level measurements indicated a low photocatalytic activity of CaNb2O6 as no photocurrent could be detected. Further investigations are needed to identify the cause of the photocurrent limitations. Nevertheless probable explanations could be low conductivity in CaNb2O6, high concentrations of recombination centers or slow charge transfer kinetics. The latter was confirmed for porous oxide layers as the addition of a hole scavenger increased the measured photocurrent. Positive photocurrent transients were also observed for porous CaNb2O6 films and could be related to either the diffusion of electrons through the porous oxide layer or to a photoanodic decomposition of the photocatalyst.
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Hürlimann, Martin Dominik. "Cryogenic hydrogen maser." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/29116.
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A new type of atomic hydrogen maser that operates in a dilution refrigerator has been developed. In this device, the hydrogen atoms circulate back and forth between a microwave pumped state invertor in high field and the maser cavity in zero field.
A prototype maser with a small maser cavity has been built and the results obtained so far are encouraging. Stable maser oscillations were observed for temperatures of the maser bulb between 230 mK and 660 mK and for densities up to 3 x 1012cm⁻³. The short term frequency stability was measured with the help of two high quality quartz crystal oscillators by the three-cornered-hat method. The observed fractional frequency fluctuations for an averaging time of 1 s were 6.3 ± 3.7 x 10⁻¹⁴, which is lower than the results from the best room temperature masers. In conjunction with the stability measurements, the phase noise of the maser electronics was investigated. In particular, the temperature dependence of the phase noise of the cooled preamplifier was measured and it was shown that anomalous high noise levels between 2.2 K and 4.2 K are caused by the boiling of the liquid helium.
From the temperature dependence of the maser frequency, the binding energy E[sub B] of H on ⁴He could be determined to a high precision. The result is E[sub B] = 1.011 ± 0.010 K.
An extensive computer simulation program has been written that models the operation of the cryogenic hydrogen maser. It has been used to analyze and interpret some of the data. In addition, this simulation program is helpful for the design of an improved second generation cryogenic maser. Based on the present data and the model calculations, a new pumping scheme is proposed that is expected to increase the efficiency of the state invertor significantly.Science, Faculty of
Physics and Astronomy, Department of
Graduate
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Almazroai, Layla S. "Photocatalytic hydrogen production." Thesis, Cardiff University, 2009. http://orca.cf.ac.uk/54920/.
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Due to the environmental problems arising from the combustion of fossil fuels and their depletion, the production and use of renewable fuels have grown rapidly in recent years. Hydrogen is among the promising fuels of the future as the only material that can be produced from the burning of hydrogen in air is water. The production of hydrogen by the photocatalytic water splitting method involving a semiconductor is a promising development in the field of energy and the environment, and this technique was employed in this work. TiO2 and palladium were the main photoactive support and loaded metal used in this project, respectively. The hydrogen production, whether from water/methanol solution or water alone, was investigated by illumination of the catalyst by UV irradiation produced from an Xe arc lamp. The reactions were performed in liquid or gas phase under an argon atmosphere as an inert gas. The gaseous products were collected and analysed using gas chromatography. The main method used in Pd loading was the impregnation method. 0.5% and 0.1% wt Pd loading were the best in terms of hydrogen production rate in liquid and gas phase reactions respectively. 0.5% Pd/TiO2 (P25) was used in the remaining experiments to investigate some of the variables, to maximize the rate of H2 production. Glycerol displayed an activity and produced hydrogen and carbon dioxide, as in the case of methanol but in much higher quantities. Loading of mesoporous TiO2 by a different weight of Pd, which had a high surface area, gave less hydrogen than Pd/P25 whether in liquid or gas phase reactions. The efficiency of Pd loaded titania (P25, pure anatase or anatase prepared by CHFS) doped by non-metals such as nitrogen, silver or strontium was low and less than Pd/TiO2. Hydrogen produced over Pd/TiO2, Au/TiO2 and TiO2 from water photolysis was also very low. The recombination between hydrogen and oxygen (back reaction) was studied over these catalysts and it was found that it was fastest on Pd/TiO2 whether in the dark or in the presence of light. For Au/TiO2, the light enhanced the hydrogen and oxygen reaction.
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Pearce, Steven Mitchell. "Hydrogen enhanced combustion." Thesis, University of Canterbury. Mechanical Engineering, 2000. http://hdl.handle.net/10092/6047.
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Current four stroke engine research objectives focus on increasing part load thermal efficiency while reducing exhaust emissions. Methods currently employed to achieve this are homogeneous charge lean burn technology, stratified charge lean burn technology and the use of alternative fuels. Of all possible alternative fuels hydrogen is viewed by many as being, ultimately, the fuel of the future. Methanol is regarded as being a likely transitional fuel between the current petroleum transport fuels and hydrogen. Hydrogen is known to be effective in extending the operating lean limit of an engine when used in small amounts in conjunction with conventional fuels.
This thesis presents the results of an investigation into the use of hydrogen as a supplementary fuel in a methanol fuelled Ricardo E6 engine. Three methods of introducing supplementary hydrogen into the engine were investigated: Untimed manifold injection, early direct injection and injection through a modified spark-plug.
Suitable injection systems were designed and tested on the Ricardo E6 engine. An engine management system, data acquisition system and post processing software were developed to enable data to be acquired and analyzed. The direct injection systems were the subject of schlieren visualization investigations of injected gas distribution to improve performance and elucidate engine related phenomena. Results detailing the effects of hydrogen supplementation on the engine performance, combustion and exhaust gas emissions are presented and discussed.
The early direct injection of hydrogen through a dedicated cylinder head tapping proved to be the least effective method of introducing supplementary hydrogen in the Ricardo E6 engine. The position of the injector diametrically opposite the spark-plug coupled with low levels of bulk mixture motion in the cylinder resulted in the formation of an inversely stratified charge (lean near spark-plug) even when injection commenced very early in the compression stroke. The inversely stratified charge resulted in a given level of hydrogen supplementation not being as effective as was the case in the other two fuelling systems.
The homogeneous air/fuel mixture formed by the untimed manifold injection of hydrogen was found to have a beneficial effect on both the combustion and emissions of the engine especially in lean air/fuel mixtures. Introducing supplementary hydrogen into the inlet manifold of the engine was however found to reduce the volumetric efficiency of the engine, reducing the level of output power produced by the engine.
Injecting hydrogen through a modified spark-plug was found to be the most effective way of introducing supplementary hydrogen. The improved performance of the modified spark-plug system over the other two systems was found to be due to the presence of a localized hydrogen/air mixture at the spark-plug electrodes at the time of ignition. Extension of the lean limit past that possible with methanol alone was demonstrated whilst maintaining both a high thermal efficiency and low indicated specific unburned hydrocarbon emissions.
Direct injection of supplementary hydrogen into the combustion chamber, either with the aim of forming a homogeneous charge, or forming a richer air/fuel mixture in the vicinity of the spark-plug without the use of a pre-chamber, has not been reported previously in the published literature. The investigation of both of these fuelling methods is presented in this thesis and constitutes an original contribution to the field of engine research.
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Chamberlain, Charles William. "Hydrogen-antihydrogen interactions." Thesis, University of Nottingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395602.
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Dickinson, Amanda Jane. "Photocatalytic hydrogen production." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360725.
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Prior, David V. "Hydrogen-bond basicity." Thesis, University of Surrey, 1988. http://epubs.surrey.ac.uk/847920/.
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A general scale of solute hydrogen-bond basicity has been constructed using a vast body of 1:1 hydrogen-bond equilibrium constants taken from literature. The data is assembled as a series (or set) of log K values for bases measured against a given hydrogen-bond acid in dilute tetrachloromethane solution. 34 such sets have been collected and a computational method regresses the log K data into 34 optimized equations of the form; log K[(set1)] = LA[i]. log K[H][B] + De[i] (1) For each set, the constants (LA and De) characterize the particular reference acid and the log K HB values characterize (and thereby scale) the bases over all sets. Certain acid-base combinations must, however, be excluded from equation 1 and this provides evidence that the log K HB scale is not entirely general towards all reference acids. In the regression procedure, use has been made of the novel observation that the lines represented by equation 1 intersect at a point where log K = log K HB = -1. 1. It is further shown that this condition enables the estimation of 1: 1 hydrogen-bond log K values in tetrachloromethane via equation 2; log K = 0.3421. (log K HA + 1. 1)(log HB + 1. 1) - 1.094 (2) where log K HA is a scale of solute hydrogen-bond acidity. The log K HB scale has been analysed in terms of the two principle factors of basicity according to the method devised by Maria and Gal et al. This analysis is shown to be informative in establishing and interpreting the relationships of log K HB with other basicity-dependent properties. For the most part, the experimental studies undertaken are concerned with a critical examination of the existing methods of determining G and H for 1:1 hydrogen-bond formation. The customary assumption of an exclusive 1:1 model of acid-base association in dilute solution has been tested with respect to the interaction of cyclohexanone with 3,5-dichlorophenol in cyclohexane. Using infrared spectroscopy, evidence for higher complex formation is presented and a method has been developed for determining simultaneously the formation constants of both the 1: 1 (AB) and 2: 1 (A2B) complexes (K1 and K2, respectively). 2:1 complex formation is also shown to interfere significantly with the K and H values obtained from a classical calorimetric titration procedure, limiting its application to hydrogen-bonding studies. For this reason, an improved calorimetric method for the independent determination of 1:1 hydrogen-bond enthalpies has been developed. Application of the devised methods to the interaction of 3,5-dichlorophenol with series of aliphatic ketones and aliphatic ethers in cyclohexane has yielded the values of K1 and K2, together with the thermodynamic parameters (G1, H1 and S1) of 1:1 hydrogen-bond formation. Within each series, the small differences in K1 and H1 resulting from the very subtle structural variations in the base component are discussed in terms of electronic and steric effects. The values of K1 and K2 are found to be consistent with a theoretically derived equation predicting a linear relationship between log K1 and log K2, and the values of H1 are used to critically appraise the validity of the Badger-Bauer relationship.
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Zhang, Lingzhi. "Catalytic Hydrogen Production." The Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=osu1218493937.
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Schneider, Robin. "About Supersymmetric Hydrogen." Thesis, Uppsala universitet, Teoretisk fysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-329298.
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Jana, Prabhas. "Environ-friendly production of hydrogen peroxide from direct catalytic liquid phase oxidation of hydrogen or hydrogen-containing compounds." Thesis(Ph.D.), CSIR-National Chemical Laboratory, Pune, 2007. http://dspace.ncl.res.in:8080/xmlui/handle/20.500.12252/2571.
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Mostajeran, Mehdi. "Catalyzed Hydrogen Release from BH- and BNH-based Hydrogen Storage Materials." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36875.
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In order to reduce our ties to fossil-based energy and mitigate the undeniable impacts of climate change on the environment, remarkable efforts have been directed over the last 4 decades toward developing renewable energy sources such as solar, wind, geothermal, etc. For transportation applications biofuels, electricity and hydrogen all offer potential solutions although current usage is still largely linked to fossil fuels (bio-based ethanol-gasoline mixtures, power generation for battery recharging, and steam reforming for hydrogen production). While hydrogen offers the greatest potential in terms of energy density, its poor volumetric density (0.01 MJ/L at RT) requires costly compression and pressurized storage. When future technology finally allows for efficient hydrogen release from water splitting, we need to have optimal solutions in place for hydrogen storage. One promising solution is chemical hydrogen storage in which thermolysis of a chemical precursor affords a controlled hydrogen release that can then be reversed in an off-board regeneration step. With a focus on maximum gravimetric hydrogen storage, various BNH compounds have been shown to be promising chemical hydrogen storage precursors. In this Thesis we summarize the state of the art in B-N-H hydrogen storage compounds (Chapter 1) and then investigate several new chemical hydrogen storage solutions with a focus on portable power generation.
In the first project (Chapter 2) we sought to prepare a robust, base-metal borohydride hydrolysis catalyst for use in a custom hydrogen generator designed to use the reaction heat to help separate the borate spent fuel. Active ‘reverse opal’ layered double hydroxide (LDH) catalysts were prepared and tested. While the classical Ni-Mg-Al LDH released 3.4 equiv. of hydrogen at 50 °C in 150 minutes, the polystyrene templated Ni-Mg-Al catalyst released 4 equiv. of hydrogen with a higher initial rate under the same reaction conditions. The long-term objective of this project was to test these catalysts in fuel cells for underground mine forklifts with our industry collaborator (Kingston Process Metallurgy Inc.).
In the next three chapters, the synthesis and hydrogen release properties of ammine metal borohydrides [M(BH4)m(NH3)n, AMBs] were investigated. As promising hydrogen storage materials with high hydrogen content (10-15 wt%), AMBs can access lower hydrogen release temperatures resulting from the combination of protic (N-Hδ+) and hydridic (B-Hδ-) hydrogens. While AMBs also do not suffer from diborane formation that plagues thermolysis of metal borohydrides, hydrogen release is often accompanied by small concentrations of ammonia that deactivate the fuel cell catalyst. Our objective for this work was to identify base metal catalysts that could suppress ammonia formation by further reducing the energy barrier to H2 release.
In Chapter 3 our studies of the solution synthesis of AMB materials (Y, La, Zn, etc.) in coordinating solvents such as tetrahydrofuran (thf) and diethyl ether revealed the unexpected formation of ammonia-borane (H3NBH3, AB). It was shown that while the amounts of produced AB correlate with the Zhang electronegativity for the s- and p-block metals, ionic radius is a stronger determining factor for the transition metals. It was also observed that reducible metals such as Ti and V produce large amounts of AB while Zn produced the least. This knowledge was then used in Chapter 4 to prepare pure samples of the Y and La complexes, M(BH4)3(NH3)4 that were characterized by thermal analysis (TGA-MS), powder X-ray diffraction, FT-IR and 11B and 1H MAS NMR spectroscopy. Furthermore, a series of base-metal nanoparticle catalysts, prepared using a novel route from MCl2 and liquid hexylamine-borane, was shown to suppress ammonia formation from these Y and La AMBs. Immobilizing 5 wt.% of Co NPs on Y(BH4)3(NH3)4 and 5 wt.% of Fe NPs on La(BH4)3(NH3)4 resulted in reduction of ammonia release by three- and fourfold, respectively. In Chapter 5 the attempted solution synthesis of Zn(BH4)2(NH3)2 revealed complications due to preferred formation of MIZn(BH4)3 [instead of Zn(BH4)2] from the reaction of ZnCl2 and MIBH4 (MI= Li, Na, K). As a result, the mixed-metal AMB, KZn(BH4)3(NH3)n was prepared and characterized. Although the effects of both heterogeneous and homogeneous catalysts were not as pronounced as those for Y and La, using 5 wt.% FeNPs resulted in fourfold reduction in the amount of released ammonia which led to a purer hydrogen stream (98.9 mol%) compared to the uncatalyzed thermolysis (97.0 mol%).
Finally, in Chapter 6 our results are considered vs. the current state of the art and suggestions are made for further investigations.
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Dowson, A. L. "Some aspects of hydrogen absorption and hydrogen embrittlement in alpha titanium." Thesis, University of Newcastle Upon Tyne, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382542.
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Ferrari, Federica. "Data analytics for hydrogen safety: prediction of Liquid hydrogen release characteristics." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
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Hydrogen can be adopted as a clean alternative to hydrocarbons fuels in the marine sector. Liquid hydrogen (LH2) is an efficient solution to transport and store large amounts of hydrogen, thus it is suitable for the maritime field. Additional safety knowledge is required since this is a new application and emerging risk might arise. Recently, a series of LH2 large-scale release tests was carried out in an outdoor facility as well as in a closed room to simulate spills during a bunkering operation and inside the ship’s tank connection space, respectively. The extremely low boiling point of hydrogen (-253°C) can cause condensation or even solidification of air components, thus enrich with oxygen the flammable mixture. This can represent a safety concern in case of ignition of the flammable mixture of LH2 and solid oxygen, since it was demonstrated that the resulting fire may transition to detonation. In this study, the abovementioned LH2 release experiments were analysed by using an advanced machine learning approach. The aim of this study was to provide critical insights on the oxygen condensation and solidification during an LH2 accidental spill and to evaluate whether the hydrogen concentration within the gas cloud formed due to the LH2 evaporation would reach the lower flammability limit. In particular, a model was developed to predict the possibility and the location of the oxygen phase change and of the hydrogen concentration above the lower flammability limit depending on the operative conditions during the bunkering operation (e.g. LH2 flow rate). The model demonstrated accurate and reliable predicting capabilities. The outcomes of the model can be exploited to select effective safety barriers and adopt the most appropriate safety measures in case of liquid hydrogen leakage.
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BARLOCCO, ILARIA. "HYDROGEN PRODUCTION FROM CHEMICAL HYDROGEN STORAGE MATERIALS USING CARBON-BASED CATALYSTS." Doctoral thesis, Università degli Studi di Milano, 2022. http://hdl.handle.net/2434/901855.
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The aim of this thesis is to design new catalytic systems in order to improve the performances of the existing catalysts to convert formic acid (FA) and hydrazine (N2H4 · H2O) into ultra-pure hydrogen in order to be effective in the future hydrogen economy. Different are the issues to solve in order to efficiently employ these chemicals in our energy transition. In particular, efficient carbon-based heterogeneous systems can effectively make enormous difference in the production of hydrogen from liquid carriers. Indeed, metal-based catalysts and especially Pd-based ones offer enhanced activity also at room temperature, but selectivity and stability need to be improved to be industrially applicable. In addition, carbon materials have the advantage of being easily tuned through variation in their structure, for example, changing the surface area and porosity and adding functional groups or generating topological defects. Moreover, their stability in liquid phase reactions makes them auspicious candidates in catalytic processes.
For these reasons, the first part of this thesis is dedicated to the design of new catalytic materials with the aim to improve the catalytic behaviour compared to existing Pd-based catalysts for the selective decomposition of FA at mild reaction conditions. In particular, the effect of the metal-support interaction and the geometrical and electronic effect in alloyed catalysts play a fundamental role to enhance the catalytic performance (Chapter 3-5).
Chapter 3 is devoted to study the metal-support interaction by doping with O and P functionalities the carbonaceous support. In order to establish the presence of functional groups in the support and their effect on Pd nanoparticles, the obtained samples were then, characterised by Transmission Electron Microscopy (HR-TEM, STEM-HAADF and STEM-EDS) and X-ray photoelectron spectroscopy (XPS). Density functional theory (DFT) simulations provided further insights in the interaction of Pd15 cluster with different support surfaces, i.e. pristine graphene (PG), carboxyl doped graphene (G_COOH), hydroxyl doped graphene (G_OH), carbonyl doped graphene (G_CO) and phosphate doped graphene (G_PO3H).
The effect of the addition of a second metal to Pd is considered (Rh in Chapter 4 and Au in Chapter 5). In particular, in Chapter 4 the synthesis of PdRh nanoparticles with different Pd:Rh molar ratios was studied. The obtained catalysts were characterised by Transmission Electron Microscopy (TEM) and Inductively coupled plasma optical emission spectroscopy (ICP-OES). For bimetallic catalysts, EDX-STEM analysis of individual nanoparticles was employed to investigate the presence of random-alloyed nanoparticles. Finally, PdRh catalysts were tested in the liquid-phase hydrogenation of muconic acid using formic acid as hydrogen donor.
Chapter 5 combines DFT and experimental data to disclose the role of gold in enhancing activity, selectivity and stability of palladium catalyst during the formic acid decomposition. PdAu bimetallic nanoparticles with different Pd:Au molar ratio were synthesised and the obtained catalysts were characterised by using Transmission Electron Microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma optical emission spectroscopy (ICP - OES). Finally, Density functional theory (DFT) calculations on Pd15, Au15 and Pd9Au6 clusters supported on a carbon sheet were then simulated to provide atomic level understanding to the beneficial effect of gold observed in the experimental results.
In addition, in order to decrease the cost and increase the environmental benignity of the catalyst, the application of metal-free carbon materials in the formic acid dehydrogenation is investigated (Chapter 6). Indeed, Commercial graphite (GP), graphite oxide (GO), and two carbon nanofibers (CNF-PR24-PS and CNF-PR24-LHT) were used as catalysts for the metal-free dehydrogenation reaction of formic acid (FA) in liquid phase. Raman and XPS spectroscopies were employed to characterize the materials and Density Functional Theory (DFT) calculations were utilized to study the role of defects in this reaction.
In the final results chapter (Chapter 7), the above reported metal-free carbocatalysts are employed for the hydrazine hydrate dehydrogenation reaction, in order to produce H2 without the presence of CO2. A combination of DFT and experimental studies were used to unravelling the hydrazine hydrate decomposition reaction on metal-free catalysts. The study focuses on commercial graphite and two different carbon nanofibers, Pyrolytically Stripped (CNF-PS) and High Heat-Treated (CNF-HHT), respectively treated at 700 and 3000 °C to increase their intrinsic defects.
Finally, Chapter 8 presents a summary of the main findings of this work and different possibilities to continue this research study.
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Guillet, François. "Développement et optimisation d’un système de stockage d’énergie et de production d’hydrogène basé sur l’électrochimie et la chimie du zinc." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAI029.
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L’hydrogène est un vecteur énergétique qui peut être un atout pour nous aider à décarboner nos usages énergétiques. L’électrolyse de l’eau est un des moyens de production d’hydrogène qui présente un bon compromis pour obtenir un gaz en grande quantité tout en limitant le coût et l’impact environnemental. La compression est une des voies de stockage de l’hydrogène mais les électrolyseurs sont limités technologiquement pour atteindre des pressions de stockage satisfaisantes. Une des solutions pour pallier ce problème est l’électrolyse découplée. Il s’agit de séparer la production d’hydrogène et d’oxygène en deux étapes grâce à un intermédiaire oxydant/réducteur. La société Ergosup a développé le procédé ZHYNCELEC, un exemple de cette technologie qui utilise le zinc comme intermédiaire. La première étape est l’électrodéposition du zinc, ce qui acidifie la solution et permet la formation d’oxygène. Cette étape est inspirée de l’électrolyse industrielle du zinc. La deuxième étape est la réaction entre le dépôt et l’électrolyte produisant l’hydrogène et provoquant la dissolution du zinc en solution. Le sujet de cette étude est l’optimisation du procédé ZHYNCELEC.Ce travail peut être découpé en trois axes d’étude. Le premier axe concerne la sélection des différents matériaux d’électrode, choisi suivant leur performance électrochimique mais également suivant leur durabilité. Le deuxième axe a pour objectif d’optimiser la composition de l’électrolyte. Les éléments clés sont la concentration du zinc, la concentration de l’acide et la présence d’éventuels d’additifs en solution. Le troisième axe concerne l’aspect procédé et s’articule sur des conditions opératoires telles que la température, la densité de courant, la pression maximale en hydrogène ainsi que la géométrie du réacteur. Ces trois axes ne peuvent être étudiés séparément de par les interactions entre les différents paramètres, ce qui oblige à des compromis suivant l’application du procédé vouluHydrogen is an energy carrier and a potential asset for helping to lower carbon levels of energetic uses. Water electrolysis is a way of production and a good compromise to generate a large quantity of cheap and low-environmental-impact hydrogen. Compression is used to store hydrogen but electrolysers are technologically limited to reach high pressures. One solution to overcome this problem is decoupling electrolysis. It aims at separating the hydrogen and oxygen production in two steps through mediation oxydizer/reducer. Ergosup company has developed ZHYNCELEC process, using different technologies such as zinc as mediator. The first step is zinc electrodeposition which increases the acidity of solution and lead to an oxygen formation. This step is inspired by industrial zinc electro winning. The second step is the reaction between the metallic deposition and electrolyte producing hydrogen and making the dissolution of zinc. The purpose of this study is the optimisation of ZHYNCELEC process.This work can be divided in three axes of study. First, the selection of the different electrode materials. They are chosen by electrochemical performances and durability. Secondly, electrolyte composition optimization. The key factors are zinc concentration, acid concentration and the possibility of additives presences. The final axe concerns the processing aspect and the operative conditions like temperature, current density, maximal hydrogen pressure and reactor geometry. These three axes cannot be studied separately because of the interaction between the different parameters, which forces at compromising following the aim of the application of the process
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Al-Mahamad, Lamia Lafta Ghashim. "Supramolecular hydrogels and discrete structures based on metal coordination and hydrogen bonding." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3981.
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The complexation of thiolated nucleosides and nucleobases with a range of group 11 metal ions (Au(I), Ag(I), Cu(I/II), was observed to lead to the formation of hydrogels by simple inversion tests. Atomic force and electron microscopy of the xerogels showed, in many cases, the presence of fibres with lengths in the micrometre range and above; this provided evidence for the formation of coordination polymers. This thesis is concerned with the preparation, characterisation and investigation of the physical properties, mainly photoluminescence and conductivity, of these coordination polymers. 2’-Deoxy-6-thioguanosine was successfully synthesised and characterized by UV, IR, Mass, 1H-NMR, and 13C-NMR spectroscopy. The formation of coordination polymers upon reaction of Au(I), Ag(I), and Cu(II) ions with 2’-deoxy-6-thioguanosine and 6-thioguanosine in aqueous media produced hydrogels with up to 97% water+methanol by mass. The Au-6-thioguanosine gel was studied in more detail because of the interest in gold thiolate polymers and the novel properties observed for Au(I)-6-thioguanosine. Fluorescence spectroscopy observed a strong yellow emission (λmax = 606 nm) which is not present in 6-thioguanosine nor in the Au(I) solutions. The optical absorption spectrum of the coordination polymer showed a band at (λmax = 360 nm) assigned to the HOMO-LUMO transition located mainly on the S-Au-S...chain of the polymer. An induced CD band associated with the Au-S chain and an enhancement of the CD signal at shorter wavelengths, for transitions associated with the ligand, suggested the polymer has a helical structure. Further evidence was provided by analysis of the X-ray scattering pattern of the xerogel and atomic force microscopy of single fibres deposited on silicon chips. The observation of long Au(I)-6-thioguanosine fibres and strong photoluminescence suggests some delocalisation of the states associated with the Au-S chains and the possibility of electronic conductivity. This was demonstrated upon oxidative doping of Au(I)-6-thioguanosine xerogels coated over platinum microband electrodes. Treatment with iodine vapour or ([Br(C6H4)3N]SbCl6) in anhydrous acetonitrile were found to result in linear current-voltage characteristics. The temperature dependence of the conductance showed Arrhenius behaviour (over range of temperature 223 to 323 K) with an activation energy of 94 kJ mol-1. V More complex structures based on Au(I)-6-thioguanosine polymers were observed upon synthesising the polymer in the presence of duplex DNA (from calf thymus). The templating of the polymer on DNA produces long, regular, and uniform fibres with a beads-on-a-string morphology. An unusual self-assembly of Au(I)-6-thioguanosine at flat Si surfaces upon simple drop-casting, with slow evaporation was also observed. AFM images of these films showed the formation of well-defined layers, but with each layer comprising long ribbons exceeding the maximum length of the AFM scan (~15 micrometres). Ag(I)-containing hydrogels formed by reactions with 6-thioguanine, 6-mercaptopurine, and 2-thiocytosine were prepared and characterised by AFM, TEM, XPS, X-Ray, FTIR, UV-Vis, and fluorescent spectroscopy. Au(I) 2-thiocytosine was also prepared, but this produced a discrete complex rather than a gel. AFM of the Ag(I) xerogels showed the formation of very long fibres and this was confirmed by TEM images. FTIR and X-ray diffraction studies suggested the metal coordination occurred via S atoms in all three gels. The Au(I) 2-thiocytosine was found to have strong luminescence (λmax 622 nm). A new Ag(I):6-thioethero nucleoside complex was prepared containing 6-methylmercaptopurine riboside (6-MMPR) which was shown by single crystal X-ray diffraction to unexpectedly feature coordination via N7 rather than the thioether sulfur atom. Cu(II) & Co(II):6-methylmercaptopurine(6-MMP) were also synthesised as new discrete complexes. The metals binding was studied by single crystal X-ray diffraction which showed that the binding sites were N3& N9 for Cu(II) ions, and N9 for Co(II) ion in the complexes.
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Nishikiori, Tokujiro. "Electrochemical Studies on High Temperature Metal-Hydrogen Systems and Hydrogen Impermeable Materials." Kyoto University, 2001. http://hdl.handle.net/2433/150491.
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Kyoto University (京都大学)0048
新制・課程博士
博士(エネルギー科学)
甲第9044号
エネ博第31号
新制||エネ||9(附属図書館)
UT51-2001-F374
京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻
(主査)教授 伊藤 靖彦, 教授 尾形 幸生, 教授 木村 晃彦
学位規則第4条第1項該当
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Monteparo, Christopher Nicholas. "Gallium nitride sensors for hydrogen/nitrogen and hydrogen/carbon monoxide gas mixtures." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0002838.
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Shih, Kun-Long. "Distribution of hydrogen and production of energetic neutral hydrogen in the heliosphere." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186335.
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We have completed an analysis of the measurements of hydrogen Lyman-alpha resonant emission of the interplanetary gas performed by the Ultraviolet Spectrometer (UVS) aboard spacecraft Voyager 1 and Voyager 2 at 2-25 AU. Assuming the very local interstellar medium has a temperature around 10⁴ K, and a relative motion of 20-25 km/s with respect to the sun, and taking into account solar gravitation, radiation pressure, and ionization processes, the "hot" model of distribution for hydrogen atoms is found consistent with the observations of the Voyagers when the density of interstellar neutral hydrogen is ∼ 0.32 ± 0.08 cm⁻³ for the data of Voyager 1, and ∼ 0.22 ± 0.06 cm⁻³ for the data of Voyager 2. The modeling hydrogen density in VLISM determined by the observations of both Voyagers beyond 15 AU is independent of the chosen parameters, only the instrumental calibrations of both Voyagers after Jupiter and Saturn encounters could cause the discrepancy of the resulting densities. The VLISM hydrogen density reported her is more reliable than those previous observations (in Table 1.3), since those results were based on measurements in the heliocentric distance < 15 AU where model dependence is significant. The interaction between this interplanetary neutral gas and the various populations of interplanetary ions produces energetic neutral atoms, the flux of which provides us a means to investigate the dynamics and structure of the heliosphere, such as the planetary magnetosphere, the corotation interaction regions, the solar flare events, the quiet-time space, and the termination shock. Simple modeling shows that energetic neutral hydrogen (ENH) from these proton populations have distinct signatures and that the detection of these particles can reveal energy, spatial, and temporal distributions of the protons in and out of the ecliptic plane, thus providing information on the acceleration and propagation of ions in three-dimensional interplanetary space, including the solar-wing termination shock.
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Newton, Joseph Iliadis Christian. "Hydrogen burning of 17oxygen." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2010. http://dc.lib.unc.edu/u?/etd,2928.
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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2010.Title from electronic title page (viewed Jun. 23, 2010). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Physics and Astronomy." Discipline: Physics and Astronomy; Department/School: Physics and Astronomy. On t.p., 17 is superscripted.
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Assanee, Natthakich Chemical Sciences & Engineering Faculty of Engineering UNSW. "Catalysis to produce hydrogen." Awarded by:University of New South Wales. Chemical Sciences & Engineering, 2008. http://handle.unsw.edu.au/1959.4/41841.
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The present study is focused on two studies. The kinetics 0: methane steam refonning over a Ni/MgO catalyst at high pressure is reported in the first study. The second study is focused on the steam iron process over promoted Fe-oxide based catalyst using four different reductants; H2, H2 /CO mixture, CH4 and CH4 /C02 mixture. A kinetic study of methane steam reforming over a Ni/MgO catalyst at high pressure was carried out. The kinetic orders of methane and steam at 40 bars and 600 QC were found to be 0.82 and 0.62 respectively. 1~he estimation of energy of activation of the process was found to be 106 KJ/mol. T11e reaction rate data was explained by a Langmuir - Hinshelwood - Hougen - Wastson model. Four differe11t reductants (H2, H2 /CO mixture, CI-4 and CH4 /C02 mixture) , were applied for the study of the steam iron process. A study of the steam iron process using H2 as reductant focused on the first reduction of 4%Cr203 - 96% Fe203 with H2. The first reduction was found to be composed of a two step reduction up to 550 QC. The estimation of energy of activation for the process was found to be 92.4 KJ/mol and 68.2 KJ/mol respectively. The study of the steam iron process using H2 ICO mixture as reductant over 4%Cr203 - 96% Fe2O3 found that FeO was an intermediate for the reduction of Fe203 with H2ICO mixture to Fe metal. The application of methane as reductant for the steam iron process gave the worst results. As a result, NiO was added to Cr203 -Fe203 to increase the activity. Carbon formation on NiO also was found to be a serious problem. In order to minimize carbon formation on NiO, CO2 was introduced in a mix with CI-4 for the oxidation of deposited carbon during the reduction step. Although the introduction of CO2 can suppress carbon formation, the strong oxidation of reduced iron oxide by water formed during the reduction process coupled to the l1igher favorable reaction of the water gas shift reaction adversely affects the complete reduction of iron oxide to iron metal.
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Giraudeau, Franck. "Hydrogen in pressurized reactors." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0019/NQ46292.pdf.
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Baggerman, Jacob. "Photoactive hydrogen-bonded rotaxanes." [S.l. : Amsterdam : s.n.] ; Universiteit van Amsterdam [Host], 2006. http://dare.uva.nl/document/23505.
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Hahn, John J. "Hydrogen production from biomass." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/4387.
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Thesis (Ph. D.) University of Missouri-Columbia, 2006.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on August 1, 2007) Includes bibliographical references.
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Ahn, ByeoungSoo 1959. "Hydrogen in enameling steel." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=33320.
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Enameling steel, used in a vast range of applications, can suffer from a surface defect resembling fish scale. In this study, the effects of several microstructural, physical and coating factors on the hydrogen diffusion in low carbon steel were investigated using an electrochemical permeation apparatus, to find out the way to prevent the surface defects on the enamel coatings.A new mechanism explaining the formation of the surface defects on the enameling steel was proposed after summarizing the experimental results. Then, the effects of porosity, dislocation density, the surface roughness of a steel substrate, oxide passive layer and Pd coating on the hydrogen diffusion coefficient, hydrogen concentration and hydrogen flux were investigated.
The variations of hydrogen diffusion coefficient, hydrogen concentration in steel and hydrogen flux caused by all factors listed previously were calculated in order to understand the effect of these factors on hydrogen diffusion.
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Cooper, James Neil. "Positron hydrogen molecule scattering." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/12240/.
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In this thesis, we present Kohn variational calculations of scattering and annihilation parameters for very low energy interactions of positrons with molecular hydrogen. Our analysis includes the first application of the Kohn method for this system in which the interelectronic potential in the molecular target is treated explicitly. All previous Kohn calculations on positron hydrogen molecule scattering have avoided this complication by the use of the method of models. The advantage of the explicit treatment over the method of models is that it allows approximate target wavefunctions of a very high accuracy to be admitted more easily to the Kohn calculations. We find that the accuracy of the approximate target wavefunction is an extremely important factor in obtaining reliable results from the calculations. We carry out an extensive investigation of anomalous, nonphysical behaviour in the results of our Kohn calculations. Our explanations of how these anomalies arise and how they may be avoided significantly improves upon the discussions of these phenomena given in earlier accounts of positron hydrogen molecule scattering calculations by other authors. As with all previous models of positron hydrogen molecule scattering, we find discrepancies between the experimental value of the annihilation parameter, Z effective, and the theoretical value of this quantity as determined from our Kohn calculations. Limitations of the model that could explain these discrepancies are discussed and suggestions for future improvements are proposed.
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Wilkinson, David Adam. "Molecular hydrogen in galaxies." Thesis, Durham University, 1987. http://etheses.dur.ac.uk/6657/.
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This study aims to understand the key role played by molecular hydrogen in the evolution of galaxies, with a view to constraining its radial distribution in the Galaxy and the CO→H(_2) conversion factor α(_20).The star formation rate is shown to be correlated with the surface density of H(_2). A correlation between the molecular hydrogen fraction and the metallicity of a region allows the time evolution of H(_2) to be described. This leads to a modified 'Schmidt Law' of the SFR which explains quite naturally the production of galactic metallicity gradients and the constancy of the SFR in the absence of infall. A consistent closed model of the chemical evolution of the Galaxy is proposed to solve the G-dwarf problem, the stellar age-metallicity relation and the metallicity gradient, leading to the prediction of some initial amount of pre-disc processing of gas into visible and dark matter. It is found that a constant yield of metals is more appropriate than a yield proportional to metallicity. Possible time variations of the returned fraction, the dark matter fraction and the SFR are also studied. For consistency, we suggest that dark matter in the solar neighbourhood could be totally baryonic provided the Miller-Scalo IMF is modified at the lower end, that is, the dark matter resides in low mass stars or brown dwarfs. The production of metallicity gradients in spiral galaxies is shown to be a direct consequence of the radial variation of the total surface density of matter and the age of the disc. The role of molecular gas in the evolution of the Oort Cloud of comets is examined. It is shown that comet showers with a mean interval of ̴̱ 30My cannot be produced using perturbations of the Oort Cloud by known stars or molecular clouds. If there is indeed an apparent 30My periodicity in the terrestrial mass extinction and geological records, we argue that astronomically induced processes are unlikely to be the primary cause. Evidence is presented that the lifetime of the molecular gas phase is ≤ 2.lO(_8)y, and arguments, particularly from CO observations of the Virgo galaxy cluster, favouring longer lifetimes are shown to be not well founded. We suggest that the ICM in Virgo reduces the value of α(_20) as compared to isolated galaxies. From the above considerations, the radial distribution of in the Galaxy is derived and shown to agree in the inner Galaxy with that derived from ɤ-ray analysis. In the solar neighbourhood we find α(_20) = 2.5±0.5, and present evidence that α(_20) varies as a function of Galactocentric radius and from galaxy to galaxy.
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Willis, Kimberly. "Hydrogen-bonded liquid crystals." Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266002.
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Nobeli, Irene. "Characterising organic hydrogen bonds." Thesis, University College London (University of London), 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314204.
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Syed, Khurram Raza. "Electrochemical generation of hydrogen." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/13813.
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Global warming and the energy crisis are two of the greatest challenges on which mankind is currently focused. This has forced governments and other organisations to think how to protect the environment and how to reduce fuel costs. A variety of new and exciting technologies are being investigated to address the energy problem. Alternative energy sources such as solar power, fuel cells, wind power and tidal waves are active areas of commercial and scientific pursuit. A major area of current research is moving towards the hydrogen economy and hydrogen based energy systems. Hydrogen can be produced in many ways, most commonly by steam reforming of hydrocarbon (70% to 85% thermal efficiency) but the downside is that it releases carbon mono oxide (CO)), compared with commercial PEM electrolysers where performance has been reported to be 56 -73% at normal temperature pressure(NTP) with zero carbon emission. Electrochemical production of hydrogen has several advantages: (i) It gives pure hydrogen. (ii) It allows portability (e.g. Solar energy could be used to power the electrochemical cell). (iii) It can be produced on demand. The generation of Hydrogen via electrolysis has been the subject of many studies over the last two hundred years. However, there is still room for further work to improve both the efficiency of the process and methods of storage of the gas. The cleanest method at present is to produce hydrogen by electrolysis, and the main focus of this research is to design and develop such a green energy fuel cell for on-demand application. The aim of the work presented in this thesis was to further investigate the electrolysis method for hydrogen production. An Electrochemical fuel cell contains a minimum of two electrodes: the positively charged electrode called the anode where oxygen bubble will form, and the second negatively charged electrode called the cathode, where hydrogen bubbles will form during a chemical reaction caused by applying electrical current between these electrode. The project was initiated with the objective of finding a low cost solution for on-demand hydrogen generation. To establish a starting point, the first cell (cell-1) design was based on the work of Stephen Barrie Chambers (see chapter 3) to check the performance levels. The fabrication of the cell-1 design resulted in a mixture of hydrogen and oxygen in the same chamber, which means the cell-1 design, has a possible fire and explosion hazard. The device also has the drawback of lower performance of hydrogen production; columbic efficiency is between 40% to 46% at 1 amp to 3 amp current in 30% KOH alkaline solution. However, the advantage of reproducing Stephen’s innovation is that it allowed a quick and deep understanding of hydrogen generation. This thesis presents recent work on the fabrication of low cost electrolysis cells containing continuous flow alkaline (KOH, up to 30%) electrolyte using low cost electrodes (stainless steel 316) and membranes based on ultrahigh molecular weight polyethylene (UHMW PE) to produce hydrogen without the hazard of fire and explosion. In this research an On-Demand Hydrogen Generation cell-3 achieved a 95% hydrogen generation coulombic efficiency, which is about 49% efficiency improvement as compared to the stainless steel electrode, and was 22% better than the nano structured electrode. The typical cell voltage is 2.5 V at current flow ranging from 30 to 120 mA cm-2 in 30% KOH electrolyte. The achievement here of such high efficiencies paves the way for more research in the areas of space management, electrode surface structure and flow control (based on the application requirement). This invention can be used for aeronautic, marine and automotive application as well as in many other areas.
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Li, Lei. "Hydrogen supply chain design." Thesis, Bourgogne Franche-Comté, 2020. http://www.theses.fr/2020UBFCA005.
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Cette thèse contribue au déploiement de l’infrastructure liée à l’énergie renouvelable qu’est l’hydrogène, en proposant de nouvelles stratégies basées sur des approches d’optimisation. Un état de l’art sur la conception de la chaîne logistique de l’hydrogène est préalablement réalisé, et permet d’identifier dans la littérature deux perspectives de recherche. La première concerne la couverture de la chaîne logistique globale, qui n’est pas assurée, d’une part en amont au niveau de la localisation des fournisseurs de matières premières et de l’approvisionnement des centres de production (aspect transport), d’autre part en aval au niveau de la localisation des points de distribution (stations-service) et de leur approvisionnement (transport). Pour intégrer ces composantes, un nouveau modèle de planification est élaboré. Il fusionne les modèles classiques, plus précisément un modèle de HSCND (Hydrogen Supply Chain Network Design) au niveau central, c’est-à-dire au niveau de la production et du stockage, et un modèle de HSRP (Hydrogen Refueling Station Planning) en bout de chaîne, qui considère la distribution. Ce nouveau modèle intègre également la prise en compte des sources d’approvisionnement. Il est exprimé sous forme d’un programme linéaire en nombres entiers mixtes, avec pour objectif la minimisation du coût de l’hydrogène à la pompe (LCOH). Son intérêt est validé par une étude de cas représentant la Franche-Comté en France.La seconde voie explorée est l’intégration des niveaux de décision stratégique et tactique. Il s’agit d’optimiser simultanément la localisation des stations-service et des tournées de ravitaillement de ces stations, en considérant comme actées les décisions prises précédemment depuis les sources d’approvisionnement jusqu’aux centres de production en hydrogène. L’objectif est de maximiser la capture du flux de demande, tout en minimisant le coût quotidien total. Deux algorithmes approchés sont développés pour résoudre ce problème, l’un basé sur une recherche adaptative de grand voisinage, l’autre sur un algorithme génétique. Le modèle et les algorithmes proposés sont appliqués à la région Bourgogne Franche-Comté en FranceThis thesis contributes to the deployment of the hydrogen infrastructures by proposing new strategies based on optimization approaches. A state of the art on the design of the hydrogen supply chain has been previously carried out, and allows to identify in the literature two research perspectives.The first one concerns the coverage of the entire supply chain, on the one hand upstream at the level of the location of raw material suppliers and the supply of production centres (transport aspect), and on the other hand downstream at the level of the location of distribution points (refueling stations) and their supply (transport). To integrate these components, a new planning model is developed. It merges the classical models, more precisely an HSCND (Hydrogen Supply Chain Network Design) model at the central level, i.e. at the level of production and storage, and an HSRP (Hydrogen Refueling Station Planning) model at the end of the chain, which considers distribution. This new model also integrates the consideration of supply sources. It is expressed as a mixed number integer linear program, with the objective of minimizing the least cost of hydrogen (LCOH). Its interest is validated by a case study representing Franche-Comté in France.The second research area explored is the integration of the strategic and tactical decision-making levels. The aim is to simultaneously optimize the location of refueling stations and the routes to supply these stations, by considering as actuated the decisions previously taken from the supply sources to the hydrogen production centers. The objective is to maximize the refueling demand flow captured, while minimizing the total daily cost. Two metaheuristic algorithms are developed to solve this problem, one based on an adaptive large neighbourhood search, the other on a genetic algorithm. The proposed model and algorithms are applied to the Bourgogne-Franche-Comté region in France
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Liang, Da-tung. "Hydrogen attack in ceramics /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487325740718199.
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Reichle, Rainer. "Exotic Species of Hydrogen." [S.l. : s.n.], 2002. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB10236320.
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Setayandeh, Samaneh S. "Hydrogen Properties in Palladium." Thesis, Griffith University, 2021. http://hdl.handle.net/10072/404154.
Full textAbstract:
In this project the palladium-hydrogen system was investigated, using computational and experimental approaches. Computational modelling, employing ab initio calculations based on density functional theory (DFT), were done with the Quantum Espresso package, to investigate the electronic and phonon properties of PdH and its superabundant vacancy phase (Pd3VacH4), assuming that octahedral or tetrahedral lattice interstices are occupied by hydrogen, and to relate these to important physical properties, in particular the atomic volume of hydrogen in Pd and the superconducting transition temperature of PdH.
The driver for the computational part of this project was the history of DFTbased publications in the literature predicting such widely different phonon band structures that confident interpretations of the results really could not be made. Therefore, a systematic approach was followed to compare the calculated electron and phonon properties of PdH and Pd3H4 with six different DFT schemes, within the harmonic approximation. The results highlighted the excellent agreement for the electron band structure and the sensitivity of the phonon properties to the details of the schemes employed, and also confirmed the need to include anharmonicity of the H potential to obtain realistic phonon results.
The calculations predicted dynamic instability for octahedral Pd3VacH4, although the calculated lattice constant agreed with the estimated zerotemperature experimental value. This structure requires new calculations accounting for anharmonicity. The calculated lattice constant for Pd3VacH4 in the tetrahedral case was larger than any experimental value, so this alternative, while dynamically stable, is certainly not observed.
While the absolute lattice constant of PdH varied considerably between DFT schemes, it was found that the partial atomic volume of H in Pd, a relative measure, was rather robust against differing computational approaches. A significant discrepancy was demonstrated between the average DFT predictions for the atomic volume assuming octahedral-only interstitial occupancy and that calculated from neutron diffraction measurements on Pd and PdHx. Calculations for PdH with mixed octahedral and tetrahedral occupancy showed that PdH containing around 20% tetrahedral H would have the correct atomic H volume.
Within the harmonic approximation, the calculated superconducting transition temperature of octahedral PdH varied by a factor of nearly three across the six DFT schemes employed. This shows that a reliable DFT approach is needed before attempting to account for anharmonicity of the H potential. In the tetrahedral case, less discrepancy was observed between the characteristic measures of superconductivity, due to the smaller contribution of high-frequency optical branches to the electron-phonon coupling parameter, but the actual values predicted for the transition temperature should be relatively reliable because the tetrahedral site, being relatively small, should be more nearly harmonic than the octahedral site. The transition temperatures calculated for tetrahedral PdH were higher than those measured experimentally, making partial tetrahedral occupancy an interesting possibility from the superconductivity point of view.
For the experimental part of this project, high-resolution gravimetry was used to survey the pressure-composition behaviour of PdHx and PdDx formed above their critical points and cooled to room temperature, to determine if this preparation route leads to extra hydrogen and deuterium absorption compared to passage through the two-phase region. It was found that supercritical absorption shifted the low-pressure portion of the desorption isotherm towards higher concentration. However, the isotherms were shifted towards the expected H/D concentration by cycling, apparently due to introducing misfit dislocations in the sample. Hydriding the sample at room temperature and heating it to 300 ℃ under pressure instead of first heating to 300 ℃ and then loading with hydrogen unexpectedly shifted the supercritcal isotherms at 300℃ to lower pressure, pointing to a further and previously unobserved influence of defects on the absorption-desorption behaviour.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
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Goler, Sarah. "Graphene for Hydrogen Storage." Doctoral thesis, Scuola Normale Superiore, 2014. http://hdl.handle.net/11384/85861.
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[Excerpt; the whole abstract is available at pages V-VII ]: The ever dwindling supply of fossil fuels and the unsustainable growing demand
for energy due to worldwide improvements in the quality of life has
induced significant increases in fuel prices across the globe. This in turn has
lead to research in alternative energy; solar, wind, biofuels, etc. The choice of
alternative energy will depend on the specific use and the resources available in
the vicinity. One attractive possibility is hydrogen, the third most abundant element
available on Earth [1]. However, hydrogen is often found in compounds
such as water and must be extracted. The production or extraction of pure hydrogen
is an energy consuming process which still requires extensive research
to optimize the production methods. Hydrogen is what is called an energy
vector meaning that it can be used to store and transport energy. Using only
hydrogen and oxygen, hydrogen fuel cells produce electricity with water being
the only by-product. The hydrogen energy cycle is sustainable and does
not release carbon dioxide, a greenhouse gas, into the environment. However,
one of the main hurdles facing a hydrogen based energy economy is hydrogen
storage. Hydrogen is a gas at room temperature and pressure, a considerable
hindrance to engineering applicable storage devices. Ample funding and research
has been allocated to finding and implementing a safe, cheap, nontoxic,
and compact method of storing and releasing hydrogen. [...]
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Rizo, Pavel. "Mg/transition-metal nanomaterials for efficient hydrogen storage." Thesis, Paris Est, 2018. http://www.theses.fr/2018PESC1050/document.
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Nanomatériaux à base de magnésium et de métaux de transition pour un stockage efficace de l'hydrogène. Le magnésium est un élément de choix pour le stockage de l’hydrogène à l’état solide en raison de sa grande abondance dans la croûte terrestre et de ses fortes capacités de sorption massique et volumétrique de l’hydrogène. Cependant, la réaction de sorption souffre d'une cinétique lente et l'hydrure formé est trop stable pour des applications fonctionnant sous conditions ambiantes. Le premier problème peut être résolu en développant des composites associant deux hydrures, MgH2 et TiH2, à l'échelle nanométrique. Ces matériaux sont synthétisés par broyage mécanique sous atmosphère réactive. Cette technique permet la formation des nanocomposites et leur hydrogénation en une seule étape. De plus, ces matériaux peuvent être produits à grande échelle pour les besoins des applications. Les travaux ont été menés en trois parties : i) l’optimisation de la teneur en TiH2 dans le système (1-y)MgH2+yTiH2. Ceci a été accompli en ajustant la teneur en titane (0,0125 ≤ y ≤ 0,3 mole), tout en conservant une bonne cinétique, une réversibilité de l'hydrogène et une durée de vie utile. Les données montrent que la valeur y = 0,025 offre le meilleur compromis pour développer les propriétés les plus adéquates; ii) l'extension à d’autres métaux de transition pour le système 0,95MgH2 + 0,05TMHx (TM: Sc, Y, Ti, Zr, V et Nb), en évaluant la contribution de chaque additif sur la cinétique, sur la réversibilité de l'hydrogène et sur la durée de vie en cyclage; iii) la conception d'un dispositif de cyclage automatique capable de réaliser des centaines de sorption/désorption dans le but de mesurer la durée de vie des hydrures métalliques. Le travail a été effectué à l'aide de nombreuses méthodes expérimentales. Pour la synthèse, le broyage réactif sous atmosphère d'hydrogène a été principalement utilisé. La structure cristalline et la composition chimique des nanomatériaux ont été obtenues à partir de l'analyse par diffraction des rayons X (DRX). La taille et la morphologie des particules ont été déterminées par microscopie électronique à balayage et spectroscopie de rayons X à dispersion d'énergie (SEM / EDS). Les propriétés thermodynamiques, cinétiques et cycliques de la sorption d'hydrogène ont été déterminées par la méthode de SievertsMg/transition-metal nanomaterials for efficient hydrogen storageMagnesium metal is a prominent element for solid-state hydrogen storage due to its large abundance in earth’s crust and its high weight and volumetric hydrogen uptakes. However, hydrogen sorption suffers from sluggish kinetics and the formed hydride is too stable for applications working under ambient conditions. The former issue can be solved by developing composites combining two hydrides, MgH2 and TiH2 at the nanoscale. These materials are synthesized by mechanical milling under reactive atmosphere. By this technique, the formation of nanocomposites and their hydrogenation can be obtained in a single-step. Moreover, these materials can be produced at large scale for application purposes. The work focused on three topics: i) the optimization of the TiH2 content in the (1-y) MgH2+yTiH2 system. This was accomplished by optimizing the titanium content (0.0125≤y≤0.3 mole), while keeping good kinetics, hydrogen reversibility and cycle-life. The data show that y=0.025 is the best compromise to fulfill the most practical properties; ii) the extension to other transition metals for the system 0.95MgH2+0.05TMHx (TM: Sc, Y, Ti, Zr, V and Nb), evaluating the contribution of each additive to kinetics, hydrogen reversibility and cycle-life; iii) the conception of an automatic cycling device able to carry out hundreds of sorption cycles whit the aim of measuring the cycle-life of metal hydrides. The work was done using manifold experimental methods. For synthesis, reactive ball milling under hydrogen atmosphere was primarily used. The crystal structure and the chemical composition of nanomaterials was determined from X-ray diffraction (XRD) analysis. Particle size and morphology were obtained by Scanning Electron Microscopy / Energy Dispersive X-Ray Spectroscopy (SEM/EDS). Thermodynamic, kinetic and cycling properties toward hydrogen sorption were determined by the Sieverts method
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Lis, Grzegorz P. "Effects of thermal maturation on organic hydrogen-2/hydrogen-1 ratios and hydrogen isotopic exchangeability in Paleozoic marine kerogens (type-II)." [Bloomington, Ind.] : Indiana University, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3223056.
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Thesis (Ph.D.)--Indiana University, Dept. of Geological Sciences, 2006."Title from dissertation home page (viewed June 28, 2007)." Source: Dissertation Abstracts International, Volume: 67-06, Section: B, page: 3014. Advisers: Arndt Schimmelmann; Maria Mastalerz.
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Lindberg, Pia. "Cyanobacterial Hydrogen Metabolism - Uptake Hydrogenase and Hydrogen Production by Nitrogenase in Filamentous Cyanobacteria." Doctoral thesis, Uppsala University, Physiological Botany, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3541.
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Molecular hydrogen is a potential energy carrier for the future. Nitrogen-fixing cyanobacteria are a group of photosynthetic microorganisms with the inherent ability to produce molecular hydrogen via the enzyme complex nitrogenase. This hydrogen is not released, however, but is recaptured by the bacteria using an uptake hydrogenase. In this thesis, genes involved in cyanobacterial hydrogen metabolism were examined, and the possibility of employing genetically modified cyanobacteria for hydrogen production was investigated.
Nostoc punctiforme PCC 73102 (ATCC 29133) is a nitrogen-fixing filamentous cyanobacterium containing an uptake hydrogenase encoded by hupSL. The transcription of hupSL was characterised, and putative regulatory elements in the region upstream of the transcription start site were identified. One of these, a binding motif for the global nitrogen regulator NtcA, was further investigated by mobility shift assays, and it was found that the motif is functional in binding NtcA. Also, a set of genes involved in maturation of hydrogenases was identified in N. punctiforme, the hypFCDEAB operon. These genes were found to be situated upstream of hupSL in the opposite direction, and they were preceded by a previously unknown open reading frame, that was found to be transcribed as part of the same operon.
The potential for hydrogen production by filamentous cyanobacteria was investigated by studying mutant strains lacking an uptake hydrogenase. A mutant strain of N. punctiforme was constructed, where hupL was inactivated. It was found that cultures of this strain evolve hydrogen during nitrogen fixation. Gas exchange in the hupL- mutant and in wild type N. punctiforme was measured using a mass spectrometer, and conditions under which hydrogen production from the nitrogenase could be increased at the expense of nitrogen fixation were identified. Growth and hydrogen production in continuous cultures of a Hup- mutant of the related strain Nostoc PCC 7120 were also studied.
This thesis advances the knowledge about cyanobacterial hydrogen metabolism and opens possibilities for further development of a process for hydrogen production using filamentous cyanobacteria.