Accuracy in the effective diffusion coefficient of the gas diffusion layer (GDL)/microporous layer (MPL) is important to accurately predict the mass transport limitations for high current density operation of polymer electrolyte membrane (PEM) fuel cells. All the previous studies regarding mass transport limitations were limited to pure GDLs, and experimental analysis of the impact of the MPL on the overall diffusion in the porous GDL is still lacking. The MPL is known to provide beneficial water management properties at high current operating conditions of PEM fuel cells but its small pore sizes become a resistance in the diffusion path for mass transport to the catalyst layer. A modified Loschmidt cell with an oxygen-nitrogen mixture is used in this work to determine the effect of MPL on the effective diffusion coefficients. It is found that Knudsen effects play a dominant role in the diffusion through the MPL where pore diameters are less than 1 μm. Experimental results show that the effective diffusion coefficient of the MPL is only about 21% that of its GDL substrate and Knudsen diffusion accounts for 80% of the effective diffusion coefficient of the GDL with MPL measured in this study. No existing correlations can correlate the effective diffusion coefficient with significant Knudsen contribution.

In the first section, the electrical conductivity of rhodium phenylene-diisocyanide polymer is reported to be 3.4E-11 S/cm. However, the conductivity also exhibits an inverse exponential decay in air with t = 8 days. This change is attributed to the oxidation of the isocyanide functional group to an isocyanate, leading to degradation in the long-range metal-metal bonding, the dominant conductivity mechanism. Using a more stable carboxylate ligand, the Cu terephthalate (TPA) system is studied and compared against the Mg, Co, Ni, and Zn terephthalates. A synthesis in N,N-dimethylformamide (DMF) is developed and large quantities of the Cu(TPA)DMF can be synthesized in air. The crystal structure of the Cu(TPA) DMF is shown to be in the C2/m spacegroup. Upon desolvation, the Cu(TPA) is shown to have a large surface area of 625 m2/g. The magnetic susceptibility of the Cu(TPA) indicates anti-ferromagnetic coupling between adjacent Cu centers in the same dimer. The thermal stability of the Zn, Ni, Co, and Mg terephthalates is shown to increase with decreasing symmetric carboxylate stretch in the IR. The magnetic susceptibilities of the Co and Ni terephthalates have paramagnetic behavior, with a Weiss temperature of T = -12.9 K and T = 8.8 for Co(TPA) DMF and Ni(TPA)DMF respectively. A heterometallic Zn-Cu terephthalate is synthesized with Cu concentrations ranging from 0 to 100%. Upon the addition of Cu, Zn-rich frameworks increase in surface area, change in thermal stability, and increase their solvent retention from 16% to 25%. Zn is shown to couple with Cu in the same dimer at a high rate, changing the behavior of the dimer from anti-ferromagnetic to paramagnetic. The Weiss temperature suggests weak ferromagnetic interaction.

The oil is of vital importance to society due to its derivatives with large employment in economic activities and especially its use as an energy source. The economic and social expansion of the country in recent decades, it requires significant development of our infrastructure, especially in the energy sector. The oil that is positioned as the energy source worldwide leader showed marked increase in the average international price over the past years. In this adverse scenario, improvements in the process of refining the oil representing the large-scale gains for society. The present research study is to evaluate the characteristics of efficiency of catalysis of zeolites ZSM-12 for use as additives for lowcost production of heterogeneous microporous catalysts for catalytic cracking of step (FCC), allowing further reductions in the cost of refining oil. The zeolites are crystalline aluminosilicates, which, in its acid form, playing the role of the main active component of FCC catalysts. In our study the zeolite ZSM-12 (zeolite Socony Mobil) a zeolite synthesized with high SiO2/Al2O3 ratio that presents a structure formed by pores dimensional elliptical opening 12 containing tetrahedral SiO4 (or AlO4) with diameter of 5.5 x 5.9 Å. The results were very promising for the SiO2/Al2O3 ratio assessed, with high conversion and selectivity (mainly the C1 and C3), pointing to ZSM-12 that potential low cost of zeolitic additive for FCC catalysts. / O Petróleo é de vital importância para a sociedade devido aos seus derivados com largo emprego nas atividades econômicas e principalmente sua utilização como fonte energética. A expansão econômica e social do país, nas últimas décadas, vem exigindo importante desenvolvimento da nossa infra-estrutura, notadamente no setor de energia. O petróleo que se posiciona como a fonte de energia líder mundial, apresentou acentuada oscilação do preço médio internacional ao longo dos últimos anos, atingindo no segundo semestre do ano de 2008 o maior preço já praticado desde os primórdios da indústria petrolífera. Neste cenário adverso, melhorias no processo de refino do petróleo representam ganhos em larga escala para sociedade. O presente trabalho de pesquisa teve como finalidade avaliar as características de eficiência de catálise de zeólitas ZSM-12 (Zeolite Socony Mobil) para serem utilizadas como aditivos de baixo custo para produção de catalisadores heterogêneos microporosos para a etapa de craqueamento catalítico (FCC), possibilitando futuras reduções no custo de refino do petróleo. As zeólitas são aluminossilicatos cristalinos, que, na sua forma ácida, desempenham o papel de principal componente ativo dos catalisadores de FCC. A zeólita ZSM-12 apresenta uma estrutura formada por poros unidimensionais de abertura elíptica contendo 12 tetraedros SiO4 (ou AlO4), com diâmetro de 5,5 x 5,9 Å. Nos experimentos foram utilizadas amostras de ZSM- 12 de razões SiO2/Al2O3 de 50, 80, 100 e 150, e foi possível observar que quanto maior a cristalinidade da amostra (verificada por difração de raios-X) maior a conversão durante o craqueamento. A região de máximo de conversão ocorre aproximadamente na razão SiO2/Al2O3 de 80 a 100 e intervalos de tempo entre 0 e 20 minutos. Os resultados mostraram-se bastante promissores para as razões SiO2/Al2O3 avaliadas, apresentando alta conversão e seletividade (principalmente ao C1 e C3), apontando a ZSM-12 como potencial aditivo zeolítico de baixo custo para catalisadores de FCC.

Doctor Educationis / In summary, it has been shown during this study that bimetallic Fe and Mn containing catalysts can be prepared by wet impregnation and not by ion exchange because of the competition between two different metals at different oxidation number. Only a single metallic phase catalyst could be prepared successfully by using ion exchange. / South Africa

Gegenstand der Arbeit ist die PFG NMR (nuclear magnetic resonance with pulsed field gradients), wobei speziell die apparativen und experimentellen Bedingungen untersucht werden, welche sich durch die Verwendung ultra-hoher gepulster magnetischer Feldgradienten von bis zu 35T/m ergeben. Motiv für die Arbeit ist die Untersuchung von Diffusionserscheinungen in mikroporösen Wirtssystemen mit inneren magnetischen Feldgradienten oder/und kurzen T2-Relaxationzeiten. Nach Zusammenstellung der notwendigen Werkzeuge zur mathematischen Beschreibung von PFG NMR-Experimenten werden die aus der Literatur bekannten Impulssequenzen kritisch untersucht und durch eigene Weiterentwicklungen ergänzt. Für wichtige PFG NMR-Impulssequenzen wird eine verallgemeinerte Schreibweise vorgestellt und auf beliebige Formen der gepulsten magnetischen Feldgradienten ausgedehnt. Weiterhin werden Störeinflüsse auf das PFG NMR-Experiment untersucht und zunächst in allgemeiner Form Möglichkeiten zu deren Beseitigung bzw. Unterdrückung dargestellt. Die so gewonnenen Erkenntnisse fanden konkrete Anwendung bei der Konzeption und dem Bau des PFG NMR-Spektrometers Fegris 400 NT. Dieses Gerät wird, soweit es den Gegenstand der Arbeit berührt, ebenfalls beschrieben und in der Anlage dokumentiert. Abschließend sind einige Untersuchungen, die mit dem Fegris 400 NT durchgeführt wurden und in der dargestellten Form erst mit diesem Gerät möglich waren, kurz skizziert, wobei für weitergehende Informationen auf die entsprechenden Veröffentlichungen verwiesen wird.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19406号 / 工博第4122号 / 新制||工||1635(附属図書館) / 32431 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 中條 善樹, 教授 澤本 光男, 教授 赤木 和夫 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

No description available.

Tesis por compendio / [EN] The doctoral thesis presented under the title "Hybrid inorganic-organic materials for the optical recognition of neutral and anionic species" has had as its main objective the synthesis and characterization of organic-inorganic hybrid materials based on the combination of the principles of Supramolecular Chemistry and Materials Science. Recent studies confirm that cooperation between these two areas of Chemistry allow the simulation of what natural living beings have been doing for millions of years in a natural way. At cellular level, many vital functions are related to the ability of a particular receptor to recognize a particular species, giving a specific answer. But what is more interesting is that in living organisms, most of these systems do not exist as dissolved molecules, but are bounded to a (bio)organic skeleton with more or less flexibility. When we imitated these systems bearing in mind the supramolecular and analytical chemistry, we find that we need a sensory molecule able to join with the specie that we want to detect and at the same time, this union must produce a change in its physico-chemical properties giving as a result a signal. But moreover, if we take advantatge of the fact that siliceous nanostructured materials present a high physical and chemical stability and that they have cavities where the sensor system can be incorporated into, we have the synthetic hybrid organic-inorganic combination similar to the natural one. In order to develop this idea, we have used sensor systems widely studied in molecular recognition processes in aqueous media and we have applied them to the inorganic-organic hydrid materials. Therefore, the present work thesis has been structured in two parts: on the one hand, the synthesis and characterization of the functionalized inorganic porous solid materials by the study and detection of amines using the "chemodosimeter" approach. On the other hand, we have made the synthesis and characterization of the organic functionalized inorganic porous solid materials for the study and detection of anionic species through the displacement assays approach. / [ES] La tesis doctoral que se presenta bajo el título "Hybrid inorganic-organic materials for the optical recognition of neutral and anionic species" ha tenido como objetivo principal la síntesis y caracterización de materiales híbridos orgánico-inorgànicos basados en la combinación de los principios de la Química Supramolecular y la Ciencia de los Materiales. Recientes estudios corroboran que la cooperación entre estas dos áreas de la Química permite simular lo que ya hace millones de años realizan de forma natural los organismos vivos. A nivel celular, muchas de las funciones vitales están relacionadas con la habilidad de un receptor concreto para reconocer una determinada especie, dando una respuesta específica. Pero lo que resulta más interesante, es que en los organismos vivos, la mayoría de estos sistemas no existen en forma de moléculas disueltas, sino que están unidos con mayor o menor flexibilidad a un esqueleto bio(in)orgánico. Cuando imitamos estos sistemas teniendo en cuenta la química supramolecular y analítica, nos encontramos que necesitamos de una molécula indicadora que sea capaz de unirse a la especie que queremos detectar y que a su vez, esta unión produzca un cambio en las propiedades físico-químicas de la entidad para producir una señal. Pero además, si aprovechamos el hecho de que los materiales silíceos nanoestructurados presentan una alta estabilidad física y química y que proporcionan cavidades donde alojar al sistema sensor, tenemos la combinación híbrida orgánico-inorgánico sintética similar a la natural. Con el objetivo de desarrollar esta idea, hemos utilizado sistemas sensores ampliamente estudiados en procedimientos de reconocimiento molecular en disolución acuosa y los hemos aplicado a los materiales híbridos orgánico-inorgànicos. De esta manera, el trabajo de tesis se ha estructurado en dos partes: por una parte, la síntesis y caracterización de materiales sólidos inorgánicos porosos funcionalizados para el estudio y detección de aminas utilizando el procedimiento de "dosímetro químico", y en una segunda parte, se ha llevado a cabo la síntesis y caracterización de sólidos inorgánicos porosos funcionalizados para el estudio y detección de especies aniónicas mediante el procedimiento de "ensayos por desplazamiento". / [CA] La tesis doctoral que es presenta sota el títol "Hybrid inorganic-organic materials for the optical recognition of neutral and anionic species" ha tingut com objectiu principal la síntesi i caracterització de materials híbrids orgànic-inorgànics basats en la combinació dels principis de la Química Supramolecular i la Ciència dels Materials. Estudis recents corroboren que la cooperació entre aquestes dues àrees de la Química permet simular el que ja fa milions d'anys realitzen de forma natural els organismes vius. A nivell cel·lular, moltes de les funcions vitals estan relacionades amb l'habilitat d'un receptor concret per a reconèixer una espècie determinada, donant una resposta específica. Però el que és més interessant, és que als organismes vius, la majoria d'aquests sistemes no existeixen en forma de molècules dissoltes, sinó que estan units amb major o menor flexibilitat a un esquelet bio(in)orgànic. Quan imitem aquests sistemes tenint en compte la química supramolecular i analítica, ens trobem que necessitem d'una molècula indicadora que sigui capaç d'unir-se a l'espècie que volem detectar i que alhora, aquesta unió produeixi un canvi en les propietats fisico-químiques de l'entitat per produir una senyal. Però a més, si aprofitem el fet que els materials silícics nanoestructurats presenten una alta estabilitat física i química i que proporcionen cavitats on es pot allotjar el sistema sensor, tenim la combinació híbrida orgànica-inorgànica sintètica semblant a la natural. Per tal de desenvolupar aquesta idea, hem utilitzat sistemes sensors ampliament estudiats en procediments de reconeixement molecular en dissolució aquosa i els hem aplicat als materials híbrids orgànic-inorgànics. Així el present treball de Tesis s'ha estructurat en dues parts: per una banda, la síntesis i caracterització de materials sòlids inorgànics porosos funcionalitzats per l'estudi i detecció d'amines utilitzant el procediment de "dosímetre químic", i en una segona part, s'ha realitzat la síntesis i caracterització de sòlids inorgànics porosos funcionalitzats per a l'estudi i detecció d'espècies aniòniques mitjançant el procediment "d'assajos per desplaçament". / Comes Navarro, M. (2016). Hybrid inorganic-organic materials for the optical recognition of neutral and anionic species [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/62153 / Compendio

Les structures organométalliques poreuses (Metal Organic Framework, MOF) sont une nouvelle classe de matériaux, composées d'ions métalliques ou de clusters liés à des ligands organiques ou des complexes organométalliques dans des réseaux cristallins 1D, 2D ou 3D. Au cours de cette thèse la possibilité de construire de nouveaux MOF a été illustrée par le développement de matériaux MOF à base d’imidazolium, précurseur important pour la synthèse de catalyseurs. En outre, ce travail démontre l’utilité de la modification post-synthèse des MOFs par chimie organométallique de surface à visée catalytique : i) un MOF connu, UiO-66, avec des pores relativement petits a été fonctionnalisé avec un groupement amino et ses capacités d'adsorption de gaz ont été étudiées. ii) la synthèse de MOF a structure poreuse, CPO-27, MOF a été optimisée et utilisée comme précurseur pour produire un catalyseur d'hydrodésulfuration après l'introduction d'espèces actives, via la chimie organométallique de surface, dont les performances catalytiques ont été évaluées / Metal organic frameworks (MOF) are a new class of material, which consist of metal ions or clusters coordinated to organic ligands or metal-organic complexes and result in 1D, 2D or 3D crystalline networks. The possibility of constructing new MOF has been exemplified in this thesis by development of imidazolium based MOF, a highly important ligand system in catalysis. Moreover, this work has performed post synthesis modification via surface organometallic chemistry on existing MOF: i) a known MOF, UiO-66, with relatively small pores has been functionalized with amino group and its gas adsorption capacity has been investigated, ii) the syntheses of a 3D open structure MOF, CPO-27, MOFs have been optimized and used as a precursor to produce a hydrodesulfurization catalyst after introducing active species via surface organometallic chemistry approach, whose catalytic performances have been measured

Mechanisms of three reactions catalyzed by microporous materials were investigated computationally; the reactions investigated include Friedländer and Knoevenagel reactions catalyzed by Cu3BTC2 metal organic framework (MOF) and an intramolecular cyclisation of unsaturated alcohols catalyzed by zeolite H-ZSM-5. It was found that the reaction mechanisms of all three reactions are controlled by a high concentration of active sites in materials. Reaction intermediates interact with more than one active site simultaneously. This novel concept of "multiple-site" interactions is described. The concerted effect of two catalytic sites leads to a decrease of activation barriers on reaction paths of Friedländer and Knoevenagel reactions. On the contrary, a simultaneous interaction of reactants with two active sites has a negative effect on reaction rate in case of alcohol cyclization catalyzed by H-ZSM-5; it was found that the interaction with dual sites results in the increase of activation barriers and diffusion limitations. In case of Knoevenagel reaction catalyzed by CuBTC, the adsorption of reaction precursor to the reaction site allows the creation of a dynamic defect in the MOF framework that subsequently catalyses the reaction. Both, the multiple sites effect and the dynamical defect formation effect...