月あるいは火星近傍における持続可能な宇宙空間利用のために、月面および火星表層を覆う複合酸化物から成るレゴリスを資源としたその場資源利用に関する技術の発展が不可欠である。本研究では、不揮発不燃性の溶融塩を反応媒体に用い、電気化学プロセシングにより、その場資源であるレゴリスに含まれる有用な元素の分離・回収・利用する技術を新たに提案した。また、溶融ハライド塩中での各種金属元素やイオン及びその酸化物等の物理化学特性を明らかにした。 / High temperature molten salt plays a key role in power generation systems such as solar cells, nuclear fission reactor, and nuclear fusion reactor on the moon and Mars. In this thesis, the physicochemical phenomena of metallic atoms, metallic ions, and its oxides in molten halides were investigated in order to obtain fundamental knowledges for electrochemical/materials science and to develop electrochemical processing in molten salt for in-situ resource utilization. The significant effects of melt structure, melt composition, and interfacial flow phenomena on the Si electrodeposition process was discussed. The corrosion behavior of major alloys and a unique steel in molten halides was also discussed. / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University

In Hinblick auf den stetig steigenden Bedarf der chemischen Industrie an Grundstoffchemikalien und der teilweise unsicheren Versorgung mit Erdöl und Erdgas ist es notwendig alternative Rohstoffe und Verwertungspfade für die Bereitstellung von Basischemikalien zu finden. Ziel der vorliegenden Arbeit war die Untersuchung der Hydrogenolyse von Lignin in niedermolekulare Produkte unter Verwendung geeigneter Salzschmelzen. Es konnte gezeigt werden, dass Lignin in Zinkchlorid/Kaliumchloridschmelzen in niedermolekulare Produkte abgebaut werden kann. Hierbei erwiesen sich der Einsatz eines entsprechenden Eutektikums und einer Alternativschmelze mit niedrigem Schmelzpunkt als hilfreich. Durch den Einsatz verschiedener Apparaturen wurden Untersuchungen in statischer und dynamischer Atmosphäre durchgeführt. Es ergaben sich während der Untersuchung Abhängigkeiten der Hydrogenolyse von verschiedenen Reaktionsparametern. Optima der Umsetzung hinsichtlich der Reaktionsparameter Temperatur, Zeit und Ligninanteil in der Schmelze wurden herausgearbeitet. Die Ausbeute an gewünschten Flüssigprodukten wurde, im Untersuchungsbereich, an diesen Punkten maximiert. Gleichzeitig war die Rückstands- und Gasbildung eingeschränkt. Es konnten Erkenntnisse eines komplexen Systems der Abhängigkeiten der Ausbeuten an Reaktionsprodukten von den Parametern der Untersuchung gewonnen werden. Die Hydrogenolyse von Lignin führte zur Aromatisierung fester Residuen sowie zur Abreicherung von Sauerstofffunktionalitäten. Komplexe Reaktionsmechanismen bewirkten den Abbau von Methoxyl-, Carboxyl- und Hydroxylgruppen der Ligninstruktur. Carbeniumionmechanismen konnten als wichtige Reaktionen zur Spaltung von Ether Arylbindungen identifiziert werden. Die Freisetzung von Monomeren und die Polymerisation anderer Intermediäre sind durch Sekundärreaktionen denkbar. Die gebildeten Flüssigprodukte bestanden hauptsächlich aus Monoaromaten (v.a. Guajakole und Kresole) und wenigen Polyaromaten. Die Selektivität der Bildung einzelner Verbindungen war gering, d.h. die Flüssigprodukte sind eine heterogene Mischung mit geringen Konzentrationen der Einzelsubstanzen. Die Unterschiede in der Struktur der Ausgangslignine bildeten sich auch in der Zusammensetzung der Flüssigprodukte ab. / In view of the steadily increasing demand of the chemical industry to base chemicals and the partial uncertain supply of crude oil and gas, it is necessary to find alternative raw materials and conversion routes for the provision of basic chemicals. The aim of the present work was to investigate the hydrogenolysis of lignin in low molecular weight products using appropriate molten salt media. It could be demonstrated that lignin can be convert in low molecular weight products using zinc chloride/potassium chloride molten salt media. The use of an appropriate eutectic melt and of an alternative melt with low melting point proved helpful. By the use of different apparatus investigations in static and dynamic atmosphere could be carried out. During the investigation dependencies of the hydrogenolysis of various reaction parameters are submitted. Optima of the hydrogenolysis regarding to reaction temperature, time and lignin content at the melt could be identified. The yields were maximized at these points in the range of investigation. Concurrently formation of gases and residues were suppressed. Some evidence of a complex system of the dependencies of the yields of reaction products are obtained from the parameters of the investigation. Hydrogenolysis of lignin leads to aromatic solid residues and to a loss of oxygen containing structures. Structures containing methoxyl-, carboxyl- and hydroxyl groups are degraded by various complex reaction mechanisms. Mechanisms of the formation of carbonium ions were identified as important reactions of the cleavage of ether aryl bonds. Secondary reactions caused the liberation of monomers and polymerisation of some intermediaries. The resulting liquid products consist mainly of monoaromatics (guaiacols and cresols) and less of polyaromatics. The selectivity of the formation of single compounds was low, i.e. the liquid products constitute a heterogenous mixture with low concentrations of the single compounds. The structural differencies of the feedstock lignins also showed at the composition of the liquid products.

Molten Salt Fast Reactors (MSFRs) have prominent advantages such as fuel breeding, nuclear waste transmutation, and inherent safety. They are the only liquid-fueled nuclear reactors currently receiving significant attention as fourth-generation advanced nuclear systems. To address the challenges of short operational lifetimes and proliferation issues during online fuel processing, the breed-and-burn (B&B) MSFR is among the most promising advanced reactor types. In this study, a large-volume B&B MSFR model without online actinide element treatment was simulated and analyzed using the Monte Carlo simulation software SERPENT, considering different power levels and sizes of the inactive core. The results demonstrate that, under otherwise identical conditions, the operational lifetime and conversion ratio of MSFRs increase with decreasing power levels and increasing the size of the inactive core. These findings provide a foundation and theoretical basis for achieving B&B MSFRs without online actinide element treatment. / Smält saltsnabbreaktorer (MSFRs) har framträdande fördelar såsom bränsleförädling, transmutation av kärnavfall och inneboende säkerhet. De är de enda flytande drivna kärnreaktorerna som för närvarande får betydande uppmärksamhet som fjärde generationens avancerade kärnkraftverk. För att möta utmaningarna med korta driftstider och spridningsproblem vid online bränslebearbetning är rask-och-bränning (B&B) MSFR bland de mest lovande avancerade reaktortyperna. I denna studie simulerades och analyserades en storskalig B&B MSFR-modell utan behandling av aktinidelement online med hjälp av Monte Carlo simuleringsprogramvaran SERPENT, med hänsyn till olika effektnivåer och storlekar på den inaktiva kärnan. Resultaten visar att livslängden och konverteringsförhållandet för MSFRs ökar under annars identiska förhållanden i takt med att effektnivåerna minskar och storleken på den inaktiva kärnan ökar. Dessa resultat ger en grund och teoretisk grund för att uppnå B&B MSFRs utan behandling av aktinidelement online.

No description available.

No description available.

Neste trabalho tivemos como objetivo sintetizar e caracterizar os ortossilicatos de elementos alcalino-terrosos com destaque para o Sr2SiO4, uma matriz hospedeira para íons dopantes como o cádmio II e o európio III, resultando em materiais com propriedades luminescentes. Outro objetivo é reduzir a temperatura de síntese pelos métodos aqui empregados em relação aos métodos convencionais descritos na literatura. Tanto a matriz quanto os sistemas dopados foram caracterizados por meio da difratometria de raios x, análise de área superficial e tamanho de poros, microscopia eletrônica de varredura e de transmissão. Os métodos empregados neste trabalho foram basicamente o da metátese e o do sal fundido, sendo que o método da metátese foi conduzido por sol-gel (utilizando-se sílica comercial e TEOS) e por precipitação em atmosfera ambiente e em atmosfera de nitrogênio. Já no método do sal fundido utilizamos duas temperaturas de síntese, 600 e 750ºC. A 750ºC foi utilizada uma mistura equimolar de cloreto de sódio e cloreto de potássio juntamente com nitrato de estrôncio e sílica mesoestruturada na proporção molar de 2:1. A 600ºC foi utilizada somente a mistura de nitrato de estrôncio e sílica mesoestruturada também na proporção molar de 2:1. Nestas duas formas de se conduzir a síntese por sal fundido utilizamos nitrato de sódio (proporção molar de Na/Si = 0,1) a fim de se facilitar a quebra das pontes de oxigênio da sílica e verificar a influência desse reagente sobre o produto final. Já o Ca2SiO4 e o Ba2SiO4 foram sintetizados apenas a 600ºC bem como as dopagens do Sr2SiO4 (1% em mol). Os resultados mostram uma densificação do produto em relação à sílica e a obtenção de nanofibras de silicatos obtidos pelo método do sal fundido. Já no método da metátese obtivemos carbonato de estrôncio e outros tipos de silicatos. / In this work our objective was to synthesize and characterize orthosilicates of alkaline-earth elements with emphasis on Sr2SiO4. This is a silicate host matrix for doping with ions such as cadmium II and europium III, resulting in materials with luminescent properties. Another objective is to reduce the synthesis temperature using the methods employed here when compared to conventional methods described the literature. Both the matrix and the doped systems were well characterized by X-ray diffraction, surface area and pore size distribution, scanning and transmission electron microscopy. The methods employed in this study were basically the metathesis and the molten salt; the metathesis method was conducted by sol-gel (using a commercial silica and tetraethyl orthosilicate TEOS) and precipitation in air and nitrogen atmospheres. In the molten salt method, two synthesis temperatures were used: 600 and 750ºC. At 750°C an equimolar mixture of sodium chloride and potassium chloride with strontium nitrate was used in addition to mesostructured silica in the molar ratio of 2:1. At 600°C only a mixture of strontium nitrate and mesostructured silica was used, also in the molar ratio of 2:1. In these two pathways, sodium nitrate (molar ratio Na/Si = 0.1) was used in order to facilitate the breakup of the silica oxygen bridges and its influence on the final product was also studied. Furthermore, Ca2SiO4 and Ba2SiO4 were synthesized only at 600ºC and the doping of Sr2SiO4 (1 mol %) was also carried out only at 600°C. The results show a densification of the product compared to the silica precursor and the formation of silicate nanofibers by the molten salt method. In the metathesis method we obtained strontium carbonate and other types of silicates.

Neste trabalho tivemos como objetivo sintetizar e caracterizar os ortossilicatos de elementos alcalino-terrosos com destaque para o Sr2SiO4, uma matriz hospedeira para íons dopantes como o cádmio II e o európio III, resultando em materiais com propriedades luminescentes. Outro objetivo é reduzir a temperatura de síntese pelos métodos aqui empregados em relação aos métodos convencionais descritos na literatura. Tanto a matriz quanto os sistemas dopados foram caracterizados por meio da difratometria de raios x, análise de área superficial e tamanho de poros, microscopia eletrônica de varredura e de transmissão. Os métodos empregados neste trabalho foram basicamente o da metátese e o do sal fundido, sendo que o método da metátese foi conduzido por sol-gel (utilizando-se sílica comercial e TEOS) e por precipitação em atmosfera ambiente e em atmosfera de nitrogênio. Já no método do sal fundido utilizamos duas temperaturas de síntese, 600 e 750ºC. A 750ºC foi utilizada uma mistura equimolar de cloreto de sódio e cloreto de potássio juntamente com nitrato de estrôncio e sílica mesoestruturada na proporção molar de 2:1. A 600ºC foi utilizada somente a mistura de nitrato de estrôncio e sílica mesoestruturada também na proporção molar de 2:1. Nestas duas formas de se conduzir a síntese por sal fundido utilizamos nitrato de sódio (proporção molar de Na/Si = 0,1) a fim de se facilitar a quebra das pontes de oxigênio da sílica e verificar a influência desse reagente sobre o produto final. Já o Ca2SiO4 e o Ba2SiO4 foram sintetizados apenas a 600ºC bem como as dopagens do Sr2SiO4 (1% em mol). Os resultados mostram uma densificação do produto em relação à sílica e a obtenção de nanofibras de silicatos obtidos pelo método do sal fundido. Já no método da metátese obtivemos carbonato de estrôncio e outros tipos de silicatos. / In this work our objective was to synthesize and characterize orthosilicates of alkaline-earth elements with emphasis on Sr2SiO4. This is a silicate host matrix for doping with ions such as cadmium II and europium III, resulting in materials with luminescent properties. Another objective is to reduce the synthesis temperature using the methods employed here when compared to conventional methods described the literature. Both the matrix and the doped systems were well characterized by X-ray diffraction, surface area and pore size distribution, scanning and transmission electron microscopy. The methods employed in this study were basically the metathesis and the molten salt; the metathesis method was conducted by sol-gel (using a commercial silica and tetraethyl orthosilicate TEOS) and precipitation in air and nitrogen atmospheres. In the molten salt method, two synthesis temperatures were used: 600 and 750ºC. At 750°C an equimolar mixture of sodium chloride and potassium chloride with strontium nitrate was used in addition to mesostructured silica in the molar ratio of 2:1. At 600°C only a mixture of strontium nitrate and mesostructured silica was used, also in the molar ratio of 2:1. In these two pathways, sodium nitrate (molar ratio Na/Si = 0.1) was used in order to facilitate the breakup of the silica oxygen bridges and its influence on the final product was also studied. Furthermore, Ca2SiO4 and Ba2SiO4 were synthesized only at 600ºC and the doping of Sr2SiO4 (1 mol %) was also carried out only at 600°C. The results show a densification of the product compared to the silica precursor and the formation of silicate nanofibers by the molten salt method. In the metathesis method we obtained strontium carbonate and other types of silicates.

Un concept innovant de réacteurs nucléaires à sels fondus, le Thorium Molten Salt Reactor (TMSR), a été défini au LPSC Grenoble. Le présent mémoire porte sur les études, optimisations et caractérisations réalisées sur les configurations en spectre rapide de ce concept, appelées ‘TMSR non modérés' ou TMSR-NM, très prometteuses. Le cœur est un simple cylindre dans lequel circule un sel fluore contenant du LiF et le combustible. Nos études portent sur les caractéristiques de ces réacteurs en termes de sûreté, inventaire fissile, retraitement chimique, production de déchets et capacité de régénération et de déploiement. Un tel réacteur présente maints avantages intrinsèques permettant un fonctionnement simple et sûr en cycle du combustible Thorium, ainsi que l'utilisation de divers éléments fissiles au démarrage tels l'233U, 235U ou les transuraniens issus des réacteurs actuels. Ceci permettrait une transition optimisée vers le cycle Thorium tout en fermant le cycle actuel.

Technological advances results in the fact that quite a large number of electronic equipment interacts with its environment leading to the malfunction of the devices. This brings about the necessity of using proper electromagnetic (EM) wave absorbers/shields to avoid such interactions. In order to absorb EM waves in a large frequency band from several MHz to GHz, barium hexaferrite (BaHF) ceramics which are produced as textured ceramics as well as in multilayered form can be used. Textured ceramics are processed by tape casting using templated grain growth (TGG) phenomenon. In order to obtain textured ceramics, BaHF powders and platelets are required as raw materials in such a way that during sintering small size powders are directioned by large platelet surfaces. In this study, ferrite powders were synthesized by mixed oxide technique while the platelets were produced by both molten salt synthesis (MSS) and reactive templated grain growth (RTGG) methods. In the case of platelet synthesis by MSS, effects of calcination temperature and time as well as type and composition of the flux on the formation and morphology of platelets were investigated based on the XRD and SEM results. Studies have shown that KCl flux led to the formation of sharper platelet morphology, while NaCl resulted in more round shapes. However, extent of BaHF formation in the case of NaCl was higher when compared to KCl flux due to its higher wettability characteristic, and hence faster interaction with the raw materials. Since the aspect ratio of the synthesized platelets was only ca. 2-4, these platelets were not efficient for further TGG studies. Alternatively, BiFeO3 (BiF) particles having ~30-40 &mu / m average size were synthesized as seed crystals for the synthesis of BaHF platelets by RTGG method. After the washing of these platelets with dilute HNO3, pure BaHF powders and platelets were directed by tape casting which was followed by sintering using TGG phenomenon. Degree of achieved texturing in the processed ceramics was studied using Rietveld analysis, pole figure measurement and electron backscattered diffraction (EBSD).

The phase behavior of CO2 + polymer systems is of interest in polymer synthesis, flue and natural gas processing, polymer foam and nanoparticle processing, and drug delivery. Theoretical and experimental evidence suggests that CO2 is able to interact with electron donating functional groups in polymers to form weak Lewis acid – base or EDA (Electron Donor Acceptor) complexes. These complexes can have a significant effect on the phase behavior of associated CO2 + polymer systems. In spite of this, however, the phase equilibria of only a few associated CO2 + polymer systems have been measured. Some success in modeling the phase behavior of polymer solutions has been achieved by various versions of the Statistical Association Fluid Theory (SAFT), as well as by several Lattice Models. However, many of these models incorporate two to four adjustable parameters that often depend on temperature (T), pressure (P), and/or molecular weight (MW). As a result, a large amount of experimental data is required to apply these models. The goal of the present work was therefore to develop a new thermodynamic model for associating systems that would include no more than two temperature-independent adjustable parameters. The new model presented in this work is based on the Guggenheim-Huggins-Miller lattice and includes complex formation in the development of the partition function. The EOS obtained from the resulting partition function includes two mixture parameters – the enthalpy of association or complex formation and a reference value of the equilibrium constant for complex formation . Most importantly, can be obtained from in situ Attenuated Total Reflection Fourier Transform Infrared (ATR – FTIR) measurements. This work therefore demonstrates the use of ATR – FTIR spectra to obtain molecular level information regarding the interaction of CO2 and electron donating functional groups in polymers. Unlike other studies, this work uses the bending vibration of CO2 to estimate the enthalpies of association ( ) of CO2 + polymer systems. Values of were directly incorporated in the new model and were found to lie between -7 and -12 kJ/mol for the systems investigated in this work. They increased (i.e. became more negative) in the order: CO2 + PS-co-PMMA < CO2 + PMMA <CO2 + PBMA < CO2 + PSF < CO2 + PVAc < CO2 + EVA40 < CO2 + PEG. Values of the second parameter in the new EOS ( ) were obtained by fitting solubility data at one temperature. Both and were found to be temperature independent. The application of the new EOS was demonstrated by calculating the solubility (sorption) of CO2 in polymers, the extent of swelling of polymers due to CO2, and the solubility of polymers in CO2 (cloud points). Both sorption and cloud point behavior in CO2 + polymer systems could be calculated using a single value of for each binary system. Ionic Liquids (ILs) can also incorporate electron donating functional groups in their structure. Evidence for the interaction of such ILs with CO2 can be found in the large values of the enthalpies of absorption of CO2 in these ILs. The ALF EOS was therefore extended to CO2 + IL systems using the enthalpy of absorption as a measure of association ( ) in these systems. was again treated as an adjustable parameter in the calculation of the CO2 solubility in ILs. A single value of was sufficient to predict swelling in these systems within experimental error.