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Gott, Travis Matthew. "Spectroscopic and Kinetic Studies of Hydrodenitrogenation and Hydrodesulfurization over Supported Nickel Phosphide (Ni2P)." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/29536.
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This dissertation describes preparation and characterization of Ni2P catalysts and their application in hydrodesulfurization (HDS) and hydrodenitrogenation (HDN). The work carried out includes synthesis of Ni2P on different siliceous supports, SiO2 and MCM-41. It also includes characterization of these catalytic materials using X-ray diffraction (XRD), temperature-programmed reduction (TPR), Fourier transform infrared (FTIR) spectroscopy and X-ray absorbance fine structure (XAFS) spectroscopy. In situ FTIR was employed to study the acidity of Ni2P/SiO2 and probe the catalytic sites involved in the HDN of pyridine. Transient and steady-state kinetics of a surface intermediate that is formed upon pyridine adsorption and reaction was studied to elucidate the mechanism of HDN over Ni2P/SiO2. Additionally, in situ FTIR and X-ray absorption near edge structure (XANES) spectroscopy was utilized to probe the bonding, mechanism and kinetics of thiophene HDS over a novel MCM-41-supported Ni2P catalyst. The use of these techniques allowed for better understanding of the surface intermediates, mechanisms and the nature of the active sites involved in HDN and HDS.Ph. D.
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Quilfen, Cyril. "Supercritical fluids synthesis, characterization and test of HDS catalysts : Assessment of criticality of metals contained in HDS catalysts." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0405/document.
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Dans un contexte environnemental où les législations concernant la teneur ensoufre présent dans les coupes pétrolières sont de plus en plus drastiques, le développementde nouveaux catalyseurs toujours plus actifs est donc nécessaire. Cette augmentation del´activité catalytique est possible à plusieurs niveaux dont, par exemple, par l´utilisation denouveaux procédés de synthèse tel que l´emploi de la voie fluides supercritiques. Dans unpremier temps, l´objectif est d´étudier les éléments utilisés pour préparer ces catalyseurs afind´avoir une vision plus large des réserves, des utilisations, des possibilités de substitutions…La criticité de ces éléments a donc été évaluée par le biais de plusieurs indicateurs. Dans unsecond temps, la compréhension de la synthèse de catalyseurs d´hydrodésulfuration (HDS) aété étudiée. Pour cela des expériences utilisant différents solvants et précurseurs métalliquesont été suivies via des analyses in situ Raman. Après avoir défini les résultats les plusprobants, le procédé de préparation de catalyseurs HDS assisté par le CO2 supercritique(scCO2) a été optimisé à travers une étude paramétrique. Pour cela, la température, lapression, le solvant d´imprégnation, le ratio entre CO2 et solvant d´imprégnation, le temps deréaction et le chargement en métaux ont été variés. Les matériaux obtenus ont ensuite étéfinement caractérisés (microscopie, DRX, Raman, ICP, microsonde) avant d´être activés parsulfuration et testés dans différentes réactions catalytiques (hydrogénation du toluène,hydrodésulfuration du dibenzothiophène et du 4,6-diméthyldibenzothiophène)In an environmental context where legislations concerning the sulfur content in oilare increasingly drastic, the research for new and ever more active catalysts is necessary. Thisincrease of the catalytic activity is possible at several levels, for example, with the use of novelsynthetic processes such as the use of the supercritical fluids route. In a first stage, theobjective is to study the elements used to prepare these catalysts in order to have a broaderview of the reserves, the uses, the possibility of substitutions ... The criticality of these elementshas therefore been evaluated by means of several indicators. In a second stage, theunderstanding of the synthesis of hydrodesulfurization catalysts (HDS) was studied. For thispurpose, experiments using different solvents and metallic precursors were followed by in situRaman analyses. After defining the most convincing results, the process for preparing HDScatalysts assisted by supercritical CO2 medium (scCO2) was optimized through a parametricstudy. For this, temperature, pressure, impregnation solvent, ratio of CO2 to impregnationsolvent, reaction time and metal loading were varied. The materials obtained were thencharacterized (microscopy, DRX, Raman, ICP, microprobe) before being activated bysulfidation and tested in various catalytic reactions (hydrogenation of toluene,hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene)
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Hantzer, Sylvain. "Nouveaux matériaux pour la réaction d'hydrodésulfuration (HDS)." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37614274n.
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Hantzer, Sylvain. "Nouveaux materiaux pour la reaction d'hydrodesulfuration (hds)." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13120.
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Nouveau modele de phase active obtenu par interpretation des resultats de rmn du **(59)co et de microscopie electronique haute resolution pour des catalyseurs d'hydrotraitement a base de sulfure de molybdene et de cobalt. Application a d'autres systemes : nire, core, rhre et rhmo. Etude de l'empoisonnement par la porphyrine de catalyseur nimo/al::(2)o::(3)
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Lee, Yong-Kul. "Reactivity and Structure of Supported Nickel Phosphides (Ni2P) in Deep Hydrodesulfurization Catalysis." Diss., Virginia Tech, 2004. http://hdl.handle.net/10919/30228.
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This dissertation describes preparation and characterization of Ni2P catalysts and their application in deep hydrodesulfurization (HDS) of a model sulfur compound, 4,6-dimethyldibenzothiophene (4,6-DMDBT), one of the most refractory S-compounds. This topic is of great importance in addressing recently enacted environmental regulations limiting the sulfur content in fuels. The work carried out includes synthesis of Ni2P on different siliceous supports, SiO2, MCM-41, and ultra-stable Y zeolite (USY). It also includes determining the characteristics of the supported Ni2P catalysts with a wide range of techniques: X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and X-ray absorption fine structure (XAFS) spectroscopy. The use of these techniques allowed better understanding of the nature of the active sites as well as the effect of supports. Activity tests were conducted in the HDS of 4,6-DMDBT and the HDN of quinoline. The performance of the catalysts will be compared to that of a conventional sulfide hydrotreating catalyst, Ni-Mo-S/Al2O3. Investigation of the reaction mechanism in the hydrodenitrogenation (HDN) of 2-methylpiperidine together with in situ FT-IR measurements were conducted to understand how catalyst properties affect activity and selectivity.Ph. D.
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PRADO, Bruno Otávio Piedade. "HdSC: modelagem de alto nível para simulação nativa de plataformas com suporte ao desenvolvimento de HdS." Universidade Federal de Pernambuco, 2014. https://repositorio.ufpe.br/handle/123456789/12036.
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Com os grandes avanços recentes dos sistemas computacionais, houve a possibilidade de ascensão de dispositivos inovadores, como os modernos telefones celulares e tablets com telas sensíveis ao toque. Para gerenciar adequadamente estas diversas interfaces é necessário utilizar o software dependente do hardware (HdS), que é responsável pelo controle e acesso a estes dispositivos. Além deste complexo arranjo de componentes, para atender a crescente demanda por mais funcionalidades integradas, o paradigma de multiprocessamento vem sendo adotado para aumentar o desempenho das plataformas. Devido à lacuna de produtividade de sistemas, tanto a indústria como a academia têm pesquisado processos mais eficientes para construir e simular sistemas cada vez mais complexos. A premissa dos trabalhos do estado da arte está em trabalhar com modelos com alto nível de abstração e de precisão que permitam ao projetista avaliar rapidamente o sistema, sem ter que depender de lentos e complexos modelos baseados em ISS. Neste trabalho é definido um conjunto de construtores para modelagem de plataformas baseadas em processadores, com suporte para desenvolvimento de HdS e reusabilidade dos componentes, técnicas para estimativa estática de tempo simulado em ambiente nativo de simulação e suporte para plataformas multiprocessadas. Foram realizados experimentos com aplicações de entrada e saída intensiva, computação intensiva e multiprocessada, com ganho médio de desempenho da ordem de 1.000 vezes e precisão de estimativas com erro médio inferior a 3%, em comparação com uma plataforma de referência baseada em ISS.
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Prado, Bruno Otávio Piedade. "HdSC: modelagem de alto nível para simulação nativa de plataformas com suporte ao desenvolvimento de HdS." reponame:Repositório Institucional da UFS, 2014. https://ri.ufs.br/handle/riufs/1673.
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Com os grandes avanços recentes dos sistemas computacionais, houve
a possibilidade de ascensão de dispositivos inovadores, como os modernos
telefones celulares e tablets com telas sensíveis ao toque. Para gerenciar adequadamente
estas diversas interfaces é necessário utilizar o software dependente
do hardware (HdS), que é responsável pelo controle e acesso a estes
dispositivos. Além deste complexo arranjo de componentes, para atender a
crescente demanda por mais funcionalidades integradas, o paradigma de
multiprocessamento vem sendo adotado para aumentar o desempenho das
plataformas.
Devido à lacuna de produtividade de sistemas, tanto a indústria como a
academia têm pesquisado processos mais eficientes para construir e simular
sistemas cada vez mais complexos. A premissa dos trabalhos do estado da
arte está em trabalhar com modelos com alto nível de abstração e de precisão
que permitam ao projetista avaliar rapidamente o sistema, sem ter que
depender de lentos e complexos modelos baseados em ISS.
Neste trabalho é definido um conjunto de construtores para modelagem
de plataformas baseadas em processadores, com suporte para desenvolvimento
de HdS e reusabilidade dos componentes, técnicas para estimativa
estática de tempo simulado em ambiente nativo de simulação e suporte para
plataformas multiprocessadas. Foram realizados experimentos com aplica-
ções de entrada e saída intensiva, computação intensiva e multiprocessada,
com ganho médio de desempenho da ordem de 1.000 vezes e precisão de estimativas
com erro médio inferior a 3%, em comparação com uma plataforma
de referência baseada em ISS._________________________________________________________________________________________ ABSTRACT: The amazing advances of computer systems technology enabled the rise of
innovative devices, such as modern touch sensitive cell phones and tablets. To
properly manage these various interfaces, it is required the use of the Hardwaredependent
Software (HdS) that is responsible for these devices control and access.
Besides this complex arrangement of components, to meet the growing
demand for more integrated features, the multiprocessing paradigm has been
adopted to increase the platforms performance.
Due to the system design gap, both industry and academia have been researching
for more efficient processes to build and simulate systems with this
increasingly complexity. The premise of the state of art works is the development
of high level of abstraction and precise models to enable the designer
to quickly evaluate the system, without having to rely on slow and complex
models based on instruction set simulators (ISS).
This work defined a set of constructors for processor-based platforms modeling,
supporting HdS development and components reusability, techniques for
static simulation timing estimation in native environment and support for multiprocessor
platforms. Experiments were carried out with input and output intensive,
compute intensive and multiprocessed applications leading to an average
performance speed up of about 1,000 times and average timing estimation
accuracy of less than 3%, when compared with a reference platform
based on ISS.
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Saturnino, David. "Compréhension de la relation entre la structure physico-chimique et l’activité des catalyseurs d’HDS vieillis." Thesis, Lyon 1, 2014. http://www.theses.fr/2014LYO10070.
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L'hydrodésulfuration (HDS) est un procédé majeur du raffinage pétrolier pour enlever le soufre des charges, typiquement avec un catalyseur CoMoS/Al2O3. Pendant un cycle du procédé d'HDS, la désactivation du catalyseur est due à trois causes principales : dépôt de coke, dépôt de métaux et ségrégation de la phase active. L'objectif de ce travail a été l'étude de l'effet du cokage et modifications de la phase active sur la désactivation du catalyseur d'HDS (de type CoMoS/Al2O3) appliqué à l'HDS des gazoles et la recherche des paramètres clés pour l'obtention d'un catalyseur usé comparable à celui issu de raffinerie. Des tests de vieillissement accéléré ont été réalisés avec différentes charges (différentes teneurs en aromatiques), couverture en hydrogène, durée et un pré-traitement de réduction. Après chaque test, les catalyseurs ont été caractérisés en termes de texture (méthodes BET et BJH), coke (Raman, IR, TPO, RPE, ToF-SIMS) et phase active (MET/EDX, XPS, TPR). En termes de texture et coke, une teneur élevée en aromatiques dans la charge et une couverture en hydrogène faible favorisent la formation de coke. Pour augmenter l'organisation du coke par rapport au catalyseur industriel, nous avons proposé un test plus long. En termes de phase active, une longue durée, couverture en hydrogène élevée et une pré-réduction favorisent plus d'hétérogénéité des teneurs en soufre et cobalt de la phase active et la formation d'agglomérats de sulfure de cobalt. La pré-réduction semble être efficace pour simuler l'exposition à des températures élevées pendant un cycle d'HDS, ce qui conduit à la ségrégation de la phase active, une caractéristique d'un catalyseur usé industriellementHydrodesulfurization (HDS) is a major process of petroleum refining for sulphur removal, where CoMoS/Al2O3 is the typical catalyst. During the cycle of a HDS process, deactivation of the catalyst is attributed to three main causes: coke deposition (with loss of pore volume), metals deposition and segregation of the active phase. The aim of this work was to study the effect of coking and active phase changes on the deactivation of the HDS catalyst (of CoMoS/Al2O3 type) applied to the HDS of a diesel feed and find the key operating conditions to obtain a spent catalyst comparable to the industrial one. Accelerated aging tests have been performed with different feedstocks (different amounts of aromatics), hydrogen to oil ratio, duration and a pre-reduction treatment. After each test, catalysts have been characterized in terms of texture (BET and BJH methods), coke (Raman, IR, TPO, EPR, ToF-SIMS) and active phase (TEM/EDX, XPS, TPR). In terms of texture and coke, a high amount of aromatics on the feedstock and low hydrogen to oil ratio favor the formation of coke. In order to increase the organization of graphitic coke, we have proposed a longer test. In terms of active phase, a long duration, high hydrogen to oil ratio and a pre-reduction treatment favor loss of dispersion of sulphur and cobalt contents of the active phase and formation of cobalt sulfide agglomerates. Pre-reduction seems to be an effective treatment to simulate the exposure to high temperatures during a HDS cycle which results in segregation of the active phase, a fingerprint of an industrial spent HDS catalyst
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Baubet, Bertrand. "Influence de la morphologie 2D de la phase active sur la sélectivité des catalyseurs sulfures en HDS des essences." Thesis, Lyon 1, 2013. http://www.theses.fr/2013LYO10067.
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Ce travail de thèse étudie l’influence de la morphologie des feuillets de sulfure de molybdène sur la sélectivité des catalyseurs d’hydrotraitement. Les feuillets de phase active présentent en effet deux types de bords appelés « M-edge » et « S-edge » susceptibles de conduire à des réactivités différentes. Le changement de la morphologie 2D des feuillets pourrait modifier les proportions de bords M et S exposés et ainsi les propriétés catalytiques des catalyseurs sulfures. Pour cela, des catalyseurs non promus (Mo) et promus (CoMo), supportés sur alumine ont été préparés par imprégnation à sec puis sulfurés dans des conditions variées (gaz et température). Des tests catalytiques en hydrodésulfuration (HDS) sélective des essences de FCC (sélectivité HDS/HYD) ont ensuite permis d’évaluer l’impact de la morphologie en s’appuyant sur des modèles géométriques construits à partir de calculs DFT et de caractérisations expérimentales (TEM, IR (CO), TPR, XPS). Les résultats obtenus pour les catalyseurs de type Mo semblent ainsi confirmer l’influence de la morphologie 2D sur la sélectivité HDS/HYD, le bord M paraissant être le plus sélectif pour les catalyseurs non promus. Ils mettent également en évidence l’importance de la réductibilité plus ou moins marquée des bords sur les propriétés catalytiques, notamment sur le bord M. Le changement des conditions de sulfuration semble donc affecter la morphologie des particules mais également les propriétés chimiques propres à chaque bord. En ce qui concerne les catalyseurs promus, la variation des conditions de sulfuration semble agir essentiellement au niveau de la répartition du promoteur entre les bords M et S. Cependant, les interactions avec le support paraissent constituer un frein aux effets de promotion. Dans ce contexte, les sulfurations à haute température sous H2S pur permettent d’obtenir des gains significatifs en activité et sélectivité. Ces résultats semblent dus à de faibles interactions avec le support et une décoration privilégiée du bord S qui pourrait favoriser la réaction d’HDS et limiter la réaction d’HYD. Au final, les interprétations effectuées en terme de morphologie 2D tendent à confirmer que ce paramètre peut constituer un axe de développement intéressant pour les catalyseurs d’hydrotraitement. L'optimisation des conditions de sulfuration permettraient bien de faire varier la morphologie et le taux de décoration du promoteur des catalyseurs, améliorant ainsi significativement l'activité et la sélectivitéThis thesis examines the influence of the morphology of particles of molybdenum sulfide on selectivity of hydrotreating catalysts. Nanoparticles of active phase present two types of edges called “M-edge” and “S-edge” which may lead to different reactivities. The change in morphology of the 2D sheets could change the proportions of M and S edges exposed and thus the catalytic properties of sulfide catalysts. For this, non-promoted (Mo) and promoted (CoMo) catalysts, supported on alumina were prepared by dry impregnation and sulfide in various conditions (gas and temperature). Catalytic tests in selective hydrodesulfurization (HDS) of FCC gasoline (selectivity HDS /HYD) were then used to assess the impact of the morphology based on geometrical models which were constructed with DFT calculations and experimental characterizations (TEM, IR (CO), TPR, XPS). The results for Mo catalysts seem to confirm the influence of the 2D morphology selectivity HDS / HYD, M-edge appearing to be the most selective for non-promoted catalysts. They also highlight the importance of the reducibility more or less pronounced of the edges on the catalytic properties, especially on the M-edge. The different conditions of sulfidation seem to affect the morphology of the particles but also the specific chemical properties at each edge. Regarding to the promoted catalysts, the different conditions of sulfidation appear to act primarily at the distribution of the promoter between the M and S edges. However, interactions with the carrier appear to constitute an obstacle to promoting effects. In this context, sulfidations at high temperature in pure H2S lead to obtain significant gains in activity and selectivity. These results appear to be due to weak interactions with the carrier and to the presence of the promoter on the S-edge which could promote the HDS reaction and limit the HYD reaction. Finally, the interpretations made in terms of 2D morphology tend to confirm that this parameter can be an interesting line of development for hydrotreating catalysts. Optimization of the sulfidation conditions could effectively allow to vary the morphology and the rate of decoration of promoted catalysts which significantly improve the activity and selectivity
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OKUMA, Shigeru, Tatsuya SUZUKI, YoungWoo KIM, and Tatsuya KATO. "Model Predictive Control of Traffic Flow Based on Hybrid System Modeling." Institute of Electronics, Information and Communication Engineers, 2005. http://hdl.handle.net/2237/14988.
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Isaksson, Jonas. "Förbättringsåtgärder för en ökad talloljeproduktion vid Smurfit Kappa Piteå." Thesis, Luleå tekniska universitet, Industriell miljö- och processteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-61823.
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Sodapannan hos Smurfit Kappa Piteå är en av flaskhalsarna i produktionsflödet. Detta har till följd att tjockluten ackumulerar medan resterande lutar minskar, på grund av detta måste övriga enheter tidvis minska produktionen. Sodapannan har dessutom gett en varierad ångproduktion per ts (torrsubstans) lut vilket tros vara relaterat till lutens såpinnehåll, tidigare analyser påvisat stora variationer i avsåpning. Eftersom såpa har högre energivärde än svartlut ligger detta som grund till kopplingen mellan variationen i ångproduktion per ts lut och avsåpningen. Avskild såpa vidareförädlas till tallolja i hartskokeriet, Smurfit Kappa Piteå använder en HDS (hydrodynamisk separator) för att avskilja tallolja från spjälkvätska. Tallolja används bland annat för framställning av biodiesel och de senaste årens intresse för biobränslen har även bidragit med större fokus på talloljetillverkningen vid pappersbruken. Smurfit Kappa Piteå har på senare tid gjort två större förändringar som har en direkt påverkan på talloljeproduktionen. Avsåpningsparken har byggts ut och flödet av spjälkvätska har lagts om till efter avsåpning istället för före avsåpning. Företaget är därför intresserade av en djupare analys för att undersöka hur förändringarna påverkat talloljeproduktionen och vad som kan göras för att ytterligare förbättra den. I detta projekt undersöks förluster av såpa och tallolja till sodapannan, hur förlusterna påverkar ångproduktionen per ts lut samt möjliga förbättringsåtgärder för en ökad talloljeproduktion. För att utreda förlusterna genomfördes en kartering vid tio olika tillfällen där talloljeinnehåll i svartlut samt såpans talloljeinnehåll fastställdes. Från detta erhölls följande resultat; avsåpningens verkningsgrad var cirka 94 % i blandlutssteget och 0 % i mellanlutssteget. Medelutbytet av tallolja i hartskokeriet var 70 %. Resultatet från karteringen analyserades med SIMCA tillsammans med tillgängliga variabler som påverkar avsåpningen, ingen specifik variabel visades påverka avsåpningen i betydande grad. Via en sammanställning av tallolje- och såpförlusterna visades en förbättringspotential för ökad talloljeproduktion på 42 % över HDS:en och 4 % över blandlutssteget vid hypotetiska utbyten på 100 % för vardera enhet. Ur förlusterna beräknades även den extra belastning som erläggs sodapannan och hur ångproduktionen per ts lut varierade med avseende på detta. Variationen i ångproduktion per ts lut gick inte att korrelera till förlorad såpa och tallolja. Vid drift av HDS:en, bidrog dess talloljeförluster med 1,1 % ökning av medelenergi på brännluten samtidigt som förlusten av såpa vid avsåpning bidrog med en medelenergiökning på 0,3 %. Utöver detta undersöktes även talloljeproduktionen med avseende på massaproduktionen för perioden 2010-2016. Från detta kunde en tydlig årstidsvariation urskiljas. Totalutbytet av tallolja från massa hade stigit samtidigt som kvoten löv/barr minskat. De senaste månaderna påvisade ett minskat totalutbyte av tallolja från massan vilket kopplades till omläggning av spjälkvätska till efter avsåpning från att tidigare återinförts före avsåpning.
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Antunes, Florence Pereira Novais. "Determinação de propriedades e estruturas de catalisadores de sulfeto de molibdênio suportados em MgO por cálculos ab initio." Universidade Federal de Juiz de Fora, 2015. https://repositorio.ufjf.br/jspui/handle/ufjf/317.
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Associada à redução das emissões veiculares, o principal processo de interesse no hidrotratamento é a hidrodessulfurização, HDS, na qual o átomo de enxofre presente nas moléculas organosulfuradas é adsorvido no catalisador e reage com hidrogênio, formando sulfeto de hidrogênio (H2S) e os hidrocarbonetos livres de heteroátomos. As reações de HDS são exotérmicas e irreversíveis, sendo que seu mecanismo envolve reações de hidrogenólise – quebra da ligação CS – e de hidrogenação – saturação das duplas ligações. Existem divergências na literatura sobre o mecanismo dessas reações. O interesse pela área de materiais relacionados às reações deste tipo e à catálise heterogênea está em constante expansão devido à possibilidade de produzir diversos tipos de materiais de grande aplicabilidade e custos menos onerosos. Os estudos sobre HDS buscam o desenvolvimento de catalisadores com maior capacidade para promover uma remoção mais efetiva do enxofre, além de esclarecimentos referentes ao seu mecanismo. Os catalisadores mais comumente usados são compostos que possuem estruturas de MoS2 como fase ativa. Apesar de possuir atividade catalítica na forma mássica, o MoS2 geralmente é suportado em uma superfície com extensa área como suporte, geralmente óxidos, sendo a γalumina a mais utilizada. Existem diversos estudos recentes reportando uso de outros tipos de óxidos, como TiO2, sílica, zeólitas, ZrO2, MgO e óxidos mistos. No presente trabalho, é feita a proposta de dois tipos de estruturas de catalisadores de sulfeto de molibdênio suportados em MgO, através de cálculos ab initio. É de aceitação geral, hoje em dia, que a atividade dos catalisadores de HDS está fundamentalmente ligada à existência de vacâncias aniônicas de enxofre, situadas, predominantemente, nas bordas dos cristalitos da fase ativa, já que o enxofre dos planos basais está muito fortemente ligado para permitir a formação destas vacâncias. Levandose em conta que a formação de vacâncias é uma etapa crucial para HDS, procuramos obter informações estruturais mais precisas que auxiliem no entendimento dessa etapa da reação. Para isso mostramos o estudo da formação de sítios coordenativamente insaturados na borda do sulfeto de molibdênio suportado em MgO. Além disso, discutimos a interação do sulfeto com o suporte, variando o número de camadas de sulfeto e a presença de átomo promotor de cobalto na borda. Com isso, procuramos fornecer informações estruturais de modelos teóricos de MoS2 suportado em MgO utilizando DFT a fim de contribuir com estudos nesse contexto. Para isso, foi calculada a energia de formação de vacâncias, diferença da densidade de cargas eletrônicas, pDOS e análise das cargas de Bader. Concluímos que tanto o suporte quanto o átomo promotor influenciam na formação de vacâncias na borda do sulfeto de molibdênio suportado em MgO. A influência dessas variáveis está em dependência com o tamanho da lamela, proporções de átomos de enxofre de borda e tipo de interação do sulfeto com o suporte. Em geral podemos afirmar que os dois agem de modo a diminuir a energia de formação de vacâncias, contribuindo para a melhora dessa etapa.
With respect to the reduction of pollutant emission of vehicles, the main process of hydrotreatment is the hydrodesulfurization, HDS, in which the sulfur atom of the organosulfur molecules is adsorved on the catalyst and reacts with hydrogen forming hydrogen sulfide (H2S) and heteroatomfree hydrocarbons. The HDS reactions are exothermic and irreversible and their mechanisms involve hydrogenolysis reactions – the break of CS bond – and the hydrogenation – saturation of double bonds. There are many divergences in the literature about the mechanism of these reactions. The interest about these types of reactions and the heterogenous catalysis in the material field is in constant expansion due to the possibility of producing several types of materials with great applicabilities and inferior costs. The studies about HDS seek the development of catalysts with a higher capacity to promote a more effective removal of sulfur besides the elucidation of their mechanisms. The catalysts more commonly used are compounds which possess MoS2 structures as the active phase. Even though it has catalytic activity in the bulk structure, the MoS2 is generally supported on a surface with an extended area, usually oxides such as alumina, which is the most utilized. There are many recent studies γ reporting the use of other types of oxides such as TiO2, silica, zeolites, ZrO2, MgO and mixed oxides. In this present work, a proposition of two types of catalyst structures of molybdenum sulfides supported on MgO is done by means of ab initio calculations. It is commonly accepted nowadays that the activity of HDS catalysts is greatly related to the existence of anionic vacancies of sulfur located majorly on the edges of the active phase, since the sulfurs of the basal planes are strongly bonded to permit the formation of these vacancies. Taking into account that the vacancy formation is a crucial step for HDS, we sought to obtain more precise structural information to assist the understanding of this reaction step. Thereby, we presented the study of the formation of the coordenative unsaturated sites on the edge of the molybdenum sulfide supported on MgO. Moreover, we discussed about the interaction between the sulfide and the support by varying the amount of the sulfide layers and the presence of the cobalt atom on the edge. Thereby, we sought to provide structural information on the theoretical models of MoS2 supported on MgO using DFT in order to contribute with studies in this context. In order to do that, we calculated the energy of the vacancy formation, the difference of the charge densities, pDOS and Bader charge analysis. We concluded that the support and the promoting atoms influence the formation of the vacancies on the edge of the molybdenum supported on MgO. The influence of these variables depends on the size of the layer, the proportions of the sulfur atoms on the edge and the type of the interaction of the sulfide on the support. In short, we can confirm that both act to decrease the energy of the vacancy formation, thus contributing to the improvement of this step.
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Zanotello, Tatiane Cristina. "Adição de fósforo (P) em catalisadores NiMo, suportados em γ-Al2O3, Al2O3/TiO2 e TiO2 - efeito na hidrodessulfurização do tiofeno." Universidade Federal de São Carlos, 2013. https://repositorio.ufscar.br/handle/ufscar/4108.
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Previous issue date: 2013-02-18Universidade Federal de Sao Carlos
Mo, NiMo or NiMoP HDS catalysts were supported on Al2O3, Al2O3-TiO2 or TiO2. These supports were synthesized via sol-gel and in the case o TiO2 it was used a commercial sample. The active phases were introduced by impregnation. Supports and catalysts in the oxide form were characterized by X-ray diffraction (XRD), diffuse reflectance UV-Vis spectroscopy (DRSUV-Vis), thermogravimetric analyses (TG), temperature-programmed reduction with H2 (TPR-H2), N2 adsorption/desorption, energy dispersive X-ray spectroscopy (EDS), X-ray fluorescence (XRF), temperature-programmed desorption of NH3 (TPD-NH3), high resolution transmission electron microscopy (HRTEM) and evaluated at 300°C in the HDS of thiophene, used as a model molecule. Alumina presented a high specific surface area and meso/macroprous characteristics, allowing a high dispersion of the active phases, as was evidenced by XRD and DRSUV-VIS data. A HRTEM image of a NiMo/Al2O3 catalyst showed the presence of crystalline MoS2 whose activity was substantially promoted by the presence of Ni. The NiMo catalysts were active in the HDS of thiophene, however, the activity was enhanced significantly by the incorporation of P. This result corroborates the positive influence of P in the preparation of HDS catalysts. It was suggested that P must participate as promoter in the formation of the NiMoS phase during the sulfidation process of the Ni and Mo oxides. The supported NiMoP catalysts prepared in this work were more active than a commercial NiMoP/ Al2O3 catalyst, with this result validating the preparation procedures used here. The titania addition in the alumina framework led to NiMo catalysts possessing lower activity. That behavior was attributed to the formation of Ni and Mo sulfides without interaction diminishing the generation NiMoS phase, which is highly active in the HDS of sulfured organic compounds.
Catalisadores para hidrodessulfurização (HDS) contendo Mo, NiMo ou NiMo e o aditivo fósforo (P), foram suportados sobre Al2O3, Al2O3-TiO2 ou TiO2. A alumina e a alumina-titânia foram sintetizadas via sol-gel e, no caso da titânia pura, utilizada uma amostra comercial. A introdução dos sais precursores da fase ativa foi realizada via impregnação. Suportes e catalisadores na forma de óxidos foram caracterizados através de difração de raios X (DRX), espectroscopia por refletância difusa no ultravioleta visível (DRSUV-VIS), termogravimetria (TG), redução com hidrogênio à temperatura programada (RTP-H2), adsorção/dessorção de N2, espectroscopia de energia dispersiva de raios X (EDX), fluorescência de raios X (FRX), dessorção de amônia a temperatura programada (TPD-NH3), microscopia eletrônica de transmissão de alta resolução (HRTEM) e avaliados a 300⁰C na HDS do tiofeno. A alumina apresentou uma alta área superficial específica e características meso/macroporosa, possibilitando alta dispersão das fases ativas, conforme evidenciado por DRX e dados de DRSUV-VIS. A imagem de HRTEM do catalisador NiMo/Al2O3 mostrou a presença de MoS2 cuja atividade foi promovida substancialmente pela presença de Ni. Os catalisadores NiMo sobre os suportes utilizados foram ativos no HDS do tiofeno, entretanto, essa atividade foi melhorada pela incorporação de P. Esse resultado ratifica a influência positiva da utilização desse aditivo na preparação de catalisadores de HDS. O fósforo deve atuar como um promotor na formação de espécies NiMoS durante o processo de sulfetação dos óxidos de Mo e Ni. Os catalisadores NiMoP preparados neste trabalho apresentaram atividade específica superior à de um catalisador NiMoP/Al2O3 comercial, o que valida os procedimentos de preparação utilizados no trabalho. A adição de titânia na alumina durante a síntese sol-gel conduziu a catalisadores com menor atividade. Esse resultado foi atribuído à formação de sulfetos de Ni e Mo não interativos, com a consequente diminuição da formação da fase NiMoS de alta atividade no HDS de compostos organo-sulfurados.
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Okudan, M. Demet Akçil Ata Utku. "Kobalt ve molibden içeren kullanılmış hidrodesülfürizasyon (HDS) katalizör atıklarına asidik ve alkali liç uygulaması /." Isparta : SDÜ Fen Bilimleri Enstitüsü, 2009. http://tez.sdu.edu.tr/Tezler/TF01245.pdf.
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Guingouain, Martin. "Hydrodésazotation et hydrodésulfuration de molécules modèles, sur des carbures de molybdène supportés sur alumine modifée." Paris 6, 2005. http://www.theses.fr/2005PA066208.
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Myers, Sherrie. "Criterion, convergent, and discriminant validation of the Hubley Depression Scale for Older Adults (HDS-OA)." Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/13657.
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There is a current need for an accurate screening measure for depression in older adults in both clinical and research settings. The Hubley Depression Scale for Older Adults (HDS-OA; Hubley, 1998) is a short 16-item depression screen designed for the elderly that is based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). It uses a yes/no response format, large font size, and reminders of the reference period. Currently, it lacks sufficient psychometric evidence to support its use. The only other depression screen designed for older adults is the Geriatric Depression Scale (GDS; Yesavage et al., 1983). The 30-item GDS and the shorter form GDS-15 (Sheikh & Yesavage, 1986) also use a yes/no response format but are not based on DSM-IV criteria for depression.
The purpose of the study was to examine and compare the psychometric properties of the HDS-OA, GDS, and GDS-15 using a sample of 18 depressed and 18 non-depressed older adults. Validation evidence was presented to support inferences made from the HDS-OA total score, and the results of the measures were compared to determine if the HDS-OA performed as well or better than the GDS and GDS-15. Score reliability was examined through a measure of internal consistency. Construct validity was examined by correlating depression measure scores to provide evidence of convergent validity and through correlations with anxiety, cognitive status, and self-rated health scores to examine evidence of discriminant validity. Criterion-related validity was examined through differences in depressed and non-depressed group scores and levels of sensitivity and specificity found at an optimum cut score.
The study findings revealed high internal consistency for the HDS-OA, evidence of convergent validity with the GDS and GDS-15, evidence of discriminant validity when correlated with anxiety, cognitive status, and self-rated health scores, and a significant difference between group scores, which attributes to the ability of the HDS-OA to differentiate between individuals with depression and those without. In these analyses, the HDS-OA performed as well as the GDS and GDS-15. The HDS-OA revealed higher sensitivity than the GDS and GDS-15 though, indicating slightly better performance in accurately identifying individuals with depression.
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CORDERO, SANCHEZ MARIO EDGAR 37450, and SANCHEZ MARIO EDGAR CORDERO. "Análisis multiescala de un reactor de lecho percolado para un proceso de hds mediante cfd." Tesis de doctorado, Universidad Autónoma del Estado de México, 2017. http://hdl.handle.net/20.500.11799/67502.
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En este trabajo se presenta un análisis multiescala de un reactor de lecho percolado en el que tiene lugar una reacción de Hidrodesulfurización de gasóleo ligero y en donde la velocidad de reacción sigue una cinética heterogénea del tipo Langmuir/Hinshelwood Hougen/Watson (LHHW). Las escalas estudiadas fueron: (1) escala a nivel de poros en el catalizador, (2) escala a nivel de una partícula catalítica y (3) escala de un clúster de partículas catalíticas, representando al reactor. El estudio se llevó a cabo mediante la técnica de Computer Fluid Dynamics (CFD por sus siglas en inglés). En las diferentes escalas se tienen diversos objetivos de estudios: A escala poros se analizó el efecto de la microestructura de la red de poros en el comportamiento cinético, térmico y el factor de efectividad de un catalizador. A escala catalizador se analizó el efecto de la representación de geométrica de la microestructura de la red de poros en el pelle catalítico sobre los coeficientes efectivos de transporte y sobre el comportamiento cinético, térmico y el factor de efectividad de un catalizador. A escala de un conjunto de partículas catalíticas (Modelo representativo del Reactor) se estudió: (a) el efecto de la geometría del catalizador en el comportamiento hidrodinámico del Reactor de lecho escurrido (TBR por sus siglas en inglés) en donde dos fases fluidas interactúan con una fase sólida; (b) el efecto de los diferentes modelos de intercambio de momento entre fases sobre el comportamiento hidrodinámico del TBR; (c) el efecto de la geometría del catalizador y del modelo de intercambio de momento entre fases sobre el comportamiento hidrodinámico, cinético y térmico del TBR; y (d) el efecto de la representación geométrica de la microestructura de los poros del catalizador sobre el comportamiento cinético y térmico del TBR a través de los valores calculados de los coeficientes efectivos de transporte de energía y masa.
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Oliveira, De Souza Danilo. "Quick-EXAFS and hydrotreating catalysts : chemometrics contribution." Thesis, Lille 1, 2015. http://www.theses.fr/2015LIL10061/document.
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L’hydrodésulfuration (HDS) est un procédé catalytique utilisé pour éliminer le soufre des carburants. La demande mondiale de carburants propres a stimulé les recherches sur autour de ce procédé afin de mieux comprendre les mécanismes réactionnels et de produire des catalyseurs plus efficaces. Deux axes de recherches peuvent être dégagés : d’une part la formulation de nouvelles voies de synthèse permettant la production des catalyseurs plus efficaces et d’autre part la compréhension du processus catalytique au niveau moléculaire. La compréhension des transformations structurales du catalyseur au niveau moléculaire pendant la réaction ainsi que pendant la genèse de la phase active est une nécessité pour améliorer les propriétés des catalyseurs. Dans ce contexte, ce travail propose deux objectifs. En premier lieu, il présente nouvelle méthode de synthèse de catalyseurs d’HDS à base de CoMo supporté dans TiO2 par voie sol-gel. Dans un deuxième temps, le travail présente la mise-en-œuvre de la chimiometrie pour traiter des données in situ de spectroscopie d’absorption de rayons-X (XAS) qui permet d’obtenir des informations sur la structure moléculaire du catalyseur pendant son activation. Les installations synchrotron de dernière génération permettent en effet d’enregistrer des données expérimentales avec résolution temporelle de l’ordre de la seconde (Quick-EXAFS) et la chimiometrie fournit des outils d’analyse et d’interprétation pour extraire des informations sur les cinétiques de réaction et sur les transformations structurales menant à la formation de la phase active du catalyseurHydrodesulfurization (HDS) is catalytic process used to remove sulfur from petroleum feedstock. The world claim for clean fuel boosted scientists to get new insights on the catalytic reaction in order to understand the mechanisms of the process and, thus, produce catalysts that are more efficient. Such researches are based mainly in to lines: by one hand, in the formulation of new routes that lead to tailored catalysts and, by the other hand, in a better understanding of the catalytic process at the molecular and atomic level. Particularly, the later leads to an optimization of the formulation and better catalytic performance, for which is required further understanding of the molecular structure, its transformations during the reaction, the nature of active species and its genesis. In this picture, the goal of this work is twofold. First, to present a new route for produce HDS CoMo-based catalysts via one-pot sol-gel method, which revealed to have suitable macro- and microscopic properties making promising solids for further applications. Second, to adapt and use chemometrics method to treat in situ measurements, particularly, X-ray absorption spectra (XAS), to get new insights on the genesis of the catalytic active phase at the molecular level. XAS techniques is suitable to probe local atomic structure, and last generation synchrotron facilities provide conditions to perform such in situ experiments with very fast acquisition (Quick-EXAFS). Chemometrics provide a brand new scope on data analysis and interpretation for extract information on the kinetics of reaction and structure transformation that leads to the active phase of the catalysts
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Mitterauer, Lukas. "Editorial." Hochschuldidaktisches Zentrum Sachsen (HDS), 2020. https://ul.qucosa.de/id/qucosa%3A72551.
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Unter dem Titel „Regeneration Hochschullehre“ fand die Jahrestagung der dghd 2019 in Leipzig statt. Regeneration kann hier zumindest auf drei Arten interpretiert werden:
Der Hochschullehre wird in den letzten Jahren wieder ein höherer Stellenwert zugeordnet und sie erscheint wieder nach Jahren der Konzentration auf Forschung regeneriert auf der Bildfläche.
Auf der organisatorischen und institutionellen Ebene sind vor allem die Entwicklungen seit dem Start des Bolognaprozesses und dem Qualitätspakt Lehre zu nennen, durch die in der Hochschullehre – neben ihrer Aufwertung – neue Ansätze generiert wurden.
Gleichzeitig kam es mit der Schaffung von Stellen für young professionals zu einem Generationenwechsel in der Hochschuldidaktik, was automatisch auch zur Entwicklung von und Öffnung hin zu neuen Ansätzen führt.
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Zhao, Haiyan. "Catalytic Hydrogenation and Hydrodesulfurization of Model Compounds." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/26526.
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This dissertation describes two related studies on hydrogenation and hydrodesulfurization of heterocyclic S-containing compounds.
Alkyl substituted thiophenes are promising candidates for hydrogen carriers as the dehydrogenation reactions are known to occur under mild conditions. Four types of catalysts including supported noble metals, bimetallic noble metals, transition metal phosphides and transition metal sulfides have been investigated for 2-methylthiophene (2MT) hydrogenation and ring opening. The major products were tetrahydro-2-methylthiophene (TH2MT), pentenes and pentane, with very little C5-thiols observed. The selectivity towards the desired product TH2MT follows the order: noble metals > bimetallics > phosphides > sulfides. The best hydrogenation catalyst was 2% Pt/Al2O3 which exhibited relatively high reactivity and selectivity towards TH2MT at moderate temperatures. Temperature-programmed desorption (TPD) of hydrogen indicated that the H2 desorption amount was inversely related to the rate of TH2MT formation. Temperature programmed reaction (TPR) experiments revealed that pentanethiol became the major product, especially with HDS catalysts like CoMoS/Al2O3 and WP/SiO2, which indicates that poisoned or modified conventional HDS catalysts would be good candidates for further 2MT hydrogenation studies.
The role of tetrahedral Ni(1) sites and square pyramidal Ni(2) sites in Ni2P hydrotreating catalysts was studied by substitution of Ni with Fe. The Fe component was deemed as a good probe because Ni2P and Fe2P adopt the same hexagonal crystal structure, yet Fe2P is completely inactive for hydrodesulfurization (HDS). For this purpose a series of NiFeP/SiO2 catalysts were prepared with different Ni:Fe molar ratios (1:0, 3:1, 1:1, 1:3, and 0:1) and investigated in the HDS of 4,6-dimethyldibenzothiophene at 300 and 340 oC. The uniformity of the NiFe series was demonstrated by x-ray diffraction analysis and by Fourier transform infrared (FTIR) spectroscopy of adsorbed CO. The position of substitution of Fe was determined by extended X-ray absorption fine structure (EXAFS) analysis. It was found that at 300 oC the HDS activity of the catalysts decreased with increasing Fe content and that this could be explained by the substitution of Fe at the more active Ni(2) sites. As temperature was raised to 340 oC, the activity of the Fe-containing samples increased, although not to the level of Ni2P, and this could be understood from a reconstruction of the NiFe phase to expose more Ni(2) sites. This was likely driven by the formation of surface Ni-S bonds, which could be observed by EXAFS in spent samples.Ph. D.
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Hove, Mfandaidza. "The kinetics and mechanisms of the oxidation and precipitation of iron : the high density sludge (HDS) process." Doctoral thesis, University of Cape Town, 2008. http://hdl.handle.net/11427/5318.
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Includes abstract.Includes bibliographical references.
The oxidation and precipitation of iron are key reactions in the treatment of hydrometallurgical waste water and acid mine drainage (AMD) by the high density sludge process (HDS). The removal of other pollutants by adsorption and coprecipitation using this technique depends on the nature and the process by which iron is removed. Although this technique is cheap and easy to operate and therefore the most common method by which hydrometallurgical waste water is treated, there are some problems inherent in this technique. Such problems include; the formation of gelatinous sludge which is difficult to dewater, the low solids density resulting in considerable water losses and a large land area for sludge disposal, the instability of the sludge thus requiring post neutralisation stabilisation and the formation of the solids as mixed sludge, thus diminishing chances for waste material recovery, reuse or recycle. In view of the above problems, the objectives of the present study were; to gain more understanding of the oxidation and precipitation reactions of iron through investigating the effect of pH on the oxidation rate and on the chemical and physical characteristics of the iron precipitates, to make an inference on the mechanisms by which iron precipitates are formed and finally to investigate the effect of seeding on the oxidation and precipitation of iron. To achieve the set objectives, experiments were carried out in a 4 L perspex batch reactor. The reactor was fitted with four equally spaced buffles and a draft tube to maximise mixing. Ferrous iron (Fe2+) was added as FeSO4.7H2O at initial concentrations of 200 mg/L and oxidised using air. pH control was achieved by titration with either 0.1 M NaOH or 0.1 M H2SO4 through a custom made Hitech Micro Systems controller. The reactions were carried out at pH levels 6.0, 8.0, 9.0 and 10.0. Three types of materials (recycled solids, natural haematite and natural goethite) at three concentration levels (Cs = 1.0, 0.5 and 0.1) were used as seed material in the seeded experiments.
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Tiago, Ana Emília Reis da Silva Gomes. "A visita guiada pré-natal como elemento chave no acolhimento da grávida no bloco de partos do HDS." Master's thesis, Universidade de Évora, 2012. http://hdl.handle.net/10174/15609.
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A visita guiada pré-natal no bloco de partos é uma atividade do nosso quotidiano do cuidar em enfermagem e foi o eixo norteador da temática do projeto. Advém da articulação dos cuidados de saúde primários, sendo uma estratégia institucional e um pilar de humanização no acolhimento em contexto de nascimento.
A ESMO é a profissional preparada para assistir a mulher grávida / casal no processo de gravidez, parto e maternidade.
O relatório tem por objetivo descrever a intervenção realizada em contexto profissional, a visita guiada pré-natal, contemplando as três áreas de atuação (Prestação, Gestão dos Cuidados e Metodologias de Formação), com o intuito de presentear os prestadores de cuidados e seus beneficiários: grávida/casal. Desta atuação emergem instrumentos formulados (norma, guia, panfleto, poster e publicações) com orientações precisas, tendo como objetivo, além de contribuírem para o desenvolvimento e crescimento pessoal, serem também contributos relevantes para a população alvo e todos os intervenientes da instituição acolhedora; ABSTRACT:The prenatal visit in the block of births is an activity of our daily nursing care and was a guiding theme of the project. Arises from the articulation of primary health care with differentiated, and an institutional strategy and a pillar of the humanization of birth care in context.
The ESMO is prepared to assist the professional pregnant women / couples in the process of pregnancy, childbirth and motherhood. The report aims to describe the intervention performed, the guided prenatal visit, in a professional context, addressing the three areas of performance (Performance Management, Care and Training Methodologies), with the aim of giving care providers and their beneficiaries: pregnant woman / couple. This action made instruments emerge (guide, pamphlet, poster and publications) with precise guidelines, aiming, and contribute to the development and personal growth, contributions will also be relevant to the target population and all stakeholders of the host institution.
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Chassard, Orianne. "Etude de la genèse de précurseurs oxydes modifiés : influence du prétraitement sur leurs performances en HDS des gazoles." Thesis, Lille 1, 2010. http://www.theses.fr/2010LIL10189.
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La modification de précurseurs oxydes commerciaux par des molécules organiques est une voie de recherche prometteuse pour l’amélioration des performances catalytiques des catalyseurs d’HDS. Le rôle de ces agents modifiants ainsi que l’influence de la nature du précurseur oxyde de départ ne sont cependant pas bien connus.Ce travail porte donc sur l’amélioration des performances des catalyseurs d’HDS de gazoles par modification de précurseurs oxydes de type CoMoP/Al2O3 préalablement séchés ou calcinés. Des tests en micro-pilote sur charge réelle ont montré que les formulations ainsi obtenues permettent d’améliorer significativement les performances catalytiques par rapport aux catalyseurs conventionnels. Les caractérisations physico-chimiques effectuées au cours des étapes de préparation et d’activation de ces solides ont permis de mettre en évidence un effet redispersant des molécules sur les métaux actifs, redispersion en outre préservée durant la sulfuration et permettant une optimisation de la quantité de phase active « CoMoS » forméeThe modification of oxidic precursors with organic agents is a promising procedure to improve the performances of HDS catalysts. The exact role of the modifying agents and the influence of the nature of the oxidic precursor are however not well known.This study therefore deals with the improvement of gasoil HDS catalysts by modification of CoMoP/Al2O3 oxidic precursors previously dried or calcined. The modified catalysts and the reference ones are tested on real feedstocks. A large improvement of the performances is obtained upon modifications. Physico-chemical characterizations performed at each step of the preparation and activation of these catalysts have highlighted a dispersing effect of molecules on active metals, this effect being preserved after sulfidation. This leads an optimization of the amount of the active phase "CoMoS" formed
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Dumeignil, Franck. "CATALYSE ET ENVIRONNEMENT : DEVELOPPEMENT ET AMELIORATION DE PROCEDES D'HDN & HDS / ETUDE DU COMPORTEMENT DES PHASES ACTIVES IN SITU." Habilitation à diriger des recherches, Université des Sciences et Technologie de Lille - Lille I, 2005. http://tel.archives-ouvertes.fr/tel-00098387.
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Les gouvernements et l'opinion publique ont maintenant nettement pris conscience de l'absolue nécessité d'utiliser plus rationnellement et parcimonieusement les énergies fossiles, et plus particulièrement les carburants commerciaux. On distingue deux aspects essentiels à cette problématique : l'aspect écologique avec la nécessité de proposer des carburants plus ‘propres' (au travers notamment du couple interdépendant désulfuration/déazotation), et l'aspect énergétique avec la nécessité d'économiser au maximum les carburants fossiles tout en développant l'utilisation de nouvelles sources d'énergie alternatives, ce deuxième aspect étant aussi étroitement lié à la nécessité de diminuer les émissions de CO2 afin d'enrayer l'effet de serre.Dans ce contexte, les travaux de recherche effectués en France et au Japon présentés dans cet exposé portent essentiellement sur l'amélioration des procédés de désulfuration/déazotation des coupes pétrolières. En outre, des travaux de recherche plus récemment entamés constituent une ouverture vers le développement des nouvelles technologies en rapport avec l'utilisation de l'hydrogène comme nouveau vecteur d'énergie du 21ème siècle.
De nouvelles techniques de caractérisation in situ des phases actives ont été mises au point afin d'avoir une meilleure connaissance des modes de fonctionnement des catalyseurs d'hydrotraitement, ce qui a permis de mieux cibler les stratégies à mettre en œuvre pour leur amélioration. Les catalyseurs d'hydrotraitement ont été améliorés grâce à l'utilisation de nouveaux supports pour les phases actives conventionnelles à base de MoS2. De plus, les performances de nouvelles phases actives à base de métaux nobles ont aussi été évaluées. Enfin, de nouvelles technologies de purification de ces coupes pétrolières à basse consommation d'énergie ont été développées, i) la biodéazotation à l'aide d'une nouvelle bactérie, et ii) l'oxy-désulfuration/oxy-déazotation, lesquelles se sont montrées particulièrement efficaces.
Par ailleurs pour répondre à la demande croissante d'hydrogène tout en valorisant des déchets particulièrement réfractaires aux procédés de recyclage, un procédé de production d'hydrogène par réformage à la vapeur de déchets de PVC est en cours d'élaboration. Parallèlement, nous tentons actuellement de comprendre le mode de stockage/déstockage de l'hydrogène dans les oxydes mixtes (technologie propre au LCL) à l'aide de diverses techniques de caractérisations physico-chimiques.
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Dastoor, Dolly P. "Rate and predictors of decline in dementia of the Alzheimer type as measured by the Hierarchic Dementia Scale (HDS)." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0018/NQ43563.pdf.
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Babcock, Kenneth W. "Influence of mass transport limitations on kinetics of thiophene desulfurization for resids HDS catalyst in the fresh, spent, and regenerated states." Thesis, Georgia Institute of Technology, 1987. http://hdl.handle.net/1853/11870.
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Zavala, Sanchez Luz Adela. "Supported metal disulfide (TMS) catalysts for ultra-deep HDS : coupling of IR spectoscopy and microscopy for a deeper insight into active sites." Thesis, Normandie, 2019. http://www.theses.fr/2019NORMC258.
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Ce travail de thèse a permis d’obtenir une caractérisation à l’échelle atomique des feuillets (Co)MoS2 et (Ni)WS2 de catalyseurs d’hydrotraitement supportés sur alumine et de déterminer l’impact d’un additif organique, l’acide citrique (CA). Dans cette étude des techniques avancées ont été mises en œuvre telles la caractérisation par adsorption de CO à basse température suivie par spectroscopie IR (IR/CO), des calculs DFT et des observations par microscopie électronique haute résolution en mode transmission et par STEM HAADF.Sur les catalyseurs non promu à base de W et de Mo, l’adsorption de CO permet de discriminer les sites des bords M- et des bords S- des feuillets de TMS. La détermination des coefficients d’extinction molaire des bandes liées au CO adsorbé permet de déduire la morphologie des feuillets. L’HR STEM HAADF confirme que l’addition de CA modifie la morphologie des feuillets TMS d’un triangle tronqué à une forme hexagonal.Sur les catalyseurs promus NiW et CoMo, la microscopie electronique montre que l’addition de CA diminue la taille des feuillets de TMS et conduit aussi à la création de petits clusters (<1 nm). L’analyse de particules isolées par HR STEM HAADF permet d’identifier la nature des atomes du bord du feuillet de TMS. Ainsi la microscopie et l’IR/CO mettent en évidence que au sein d’un même feuillet sulfure peuvent coexister des bords totalement promus, et partiellement promusThis work was focused on obtaining an atomic scale characterization of the (Co)MoS2 and (Ni)WS2 slabs of hydrotreating catalysts supported on alumina and to determine the impact of citric acid (CA) addition. In this study, advanced techniques were implemented such as low temperature CO adsorption followed by IR spectroscopy (IR/CO), DFT calculations and high resolution electron microscopy observations in transmission mode and by STEM HAADF.On the non-promoted W and Mo catalysts, CO adsorption makes it possible to discriminate between the sites of the M- and S- edges of the TMS slabs. The determination of the molar extinction coefficients of the adsorbed CO bands allows the morphology of the slabs to be deduced. HR STEM HAADF confirms that the addition of CA modifies the morphology of the TMS slabs from a truncated triangle to a hexagonal shape.On the promoted NiW and CoMo catalysts, electron microscopy shows that the addition of CA decreases the size of the TMS slabs and also leads to the creation of very small clusters (<1 nm). The analysis of isolated particles by HR STEM HAADF allows identifying the nature of the atoms on the edge of the TMS slabs. Thus microscopy and IR/CO show that within the same sulfide slabs, can coexist edges that are fully promoted and partially promoted
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Michaux, Olivier. "Etude de la réactivité des sulfures métalliques pour la réaction d'hydrodésulfuration (HDS) une application de la RMN du métal solide à la catalyse." Grenoble 2 : ANRT, 1986. http://catalogue.bnf.fr/ark:/12148/cb375996435.
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Michaux, Olivier. "Etude de la reactivite des sulfures metalliques pour la reaction d'hydrodesulfuration (hds) : une application de la rmn du metal solide a la catalyse." Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13073.
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Proposition d'un nouveau modele de surface active grace a l'utilisation de la rmn du cobalt 59 et a l'activite des sulfures de tous les metaux de transitions. Proposition d'un nouveau modele pour l'empoisonnement des catalyseurs hds par le vanadium
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Dahlgren, Lena. "Treatment of Spent Pickling Acid from Stainless Steel Production : A review of regeneration technologies with focus on the neutralisation process for implementation in Chinese industry." Thesis, KTH, Industriell ekologi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-57907.
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Pickling is a unit operation within stainless steel production, which means treating the steel with hydrofluoric acid (HF) and nitric acid (HNO3), also called mixed acid. The whole process generates waste water streams which have to be treated before released to recipient. The aim of this degree thesis was to make an evaluation of different possibilities for reduction of emissions from the pickling process with China as a possible future market. The work consisted of two different parts; the first was to describe and evaluate different treatment methods for waste pickling acid, with emphasis on denitrification technologies. The second and main part was to make a fundamental description of the neutralisation process and outline important parameters. The work was performed by gathering information from literature but also from industry in both Sweden and China. The work has been a collaboration between the Royal Institute of Technology (KTH), the Swedish Environmental Institute (IVL) and the company Scanacon. A review of the different acid recovery methods; ionic exchange, diffusion dialysis and extraction was made. The study showed that ionic exchange is a robust method with relatively low cost and therefore it has been largely implemented both in Swedish and Chinese industry. The outflow however still requires neutralisation. Nitrate reduction can be performed as “end of pipe”, those methods investigated in this study were; biological treatment, reverse osmosis and nanofiltration. Meanwhile, internal solutions such as evaporation and electro-dialysis are two interesting technologies which reduce nitrates in combination with acid recovery. It was found that slaked lime (Ca(OH)2) is the most suitable neutralisation agent for pickling waste and, besides the choice of chemicals, many important parameters influence the process, such as the optimal pH, mixing and conditions during lime slaking. Based on information from one of the visited sites in Sweden a mass balance of the neutralisation facility was made and from that the required amount of Ca(OH)2 was calculated. The calculations were verified by an experimental part performed by IVL, using pickling acids from the same site. The amount of metals in the outgoing water was calculated using software “Medusa” but also by equilibrium equations. However, the results differed somewhat; this is probably due to the fact that Medusa takes other complexes and their interaction, besides the formed metal hydroxides, into consideration. Within the mining industry research has been made on different methods for neutralisation and some have been tested in field. An example is the High Density Sludge process (HDS), were an amount of sludge is recycled back to the neutralisation tank. It was shown that this gave improved sludge properties and decreased lime consumption. This could perhaps also be implemented for waste water in the stainless steel industry, and the method was also tested during the experimental part of this project. The dry content increased after a number of cycles but further investigation is required before any conclusion can be drawn.Betning är en enhetsprocess inom tillverkningen av rostfritt stål då godset behandlas med fluorväte syra (HF) och salpetersyra (HNO3), också kallad blandsyra. Betningen ger upphov till vatten strömmar som måste behandlas innan de släpps ut till recipienten. Syftet med det här examensarbetet var att göra en utvärdering av olika tekniker för att reducera utsläpp till vatten från betningen med Kina som potentiell framtida marknad. Arbetet bestod av två delar; den första delen var att beskriva och utvärdera olika behandlingsmetoder av förbrukade betbad med betoning på denitrifikationstekniker. Den andra och största delen var att göra en grundläggande beskrivning av neutralisationsprocessen. Studien utfördes genom att inhämta information från litteratur samt från industrin i både Sverige och Kina. Arbetet har varit ett samarbetsprojekt mellan Kungliga Tekniska Högskolan (KTH), Svenska miljöinstitutet (IVL) och företaget Scanacon. Arbetet behandlar syraåtervinningsystemen; jonbytare, diffusions dialys samt extraktion. Nitrat reduktion kan ske internt eller externt där de externa åtgärder som behandlas i denna rapport är biologisk rening, omvänd osmos och nanofiltrering. De interna metoderna avdunstning och elektrodialys är intressanta eftersom de återvinner syran samtidigt som de reducerar nitraterna avsevärt. Studien visade att jonbyte, på grund av dess robusthet och relativt låga kostnad är den mest implementerade metoden för syraåtervinning i både svensk och kinesisk industri idag. Restprodukten från jonbytaren kräver dock fortsatt behandling, där det traditionella valet är neutralisation. Studien visade att släckt kalk (Ca(OH)2) är det mest passande kemikalien för neutralisation av betsyror. Förutom kemikalieval så finns det många parametrar som påverkar effektiviteten hos processen så som pH, omrörning och förhållanden under kalksläckningen. Baserat på information ifrån ett av de besökta stålverken i Sverige, gjordes en massbalans över dess neutralisationanläggning. Utifrån de flöden som denna gav kunde den teoretiska mängden kalk som krävdes för utfällning räknas ut. Beräkningarna verifierades med en experimentell del som utfördes av IVL på betsyror från samma verk. Resthalterna av metall i utgående vatten beräknades med programmet ”Medusa” men också med jämviktsekvationer. Resultaten mellan de två skiljde sig, detta beror förmodligen på att Medusa förutom hydroxidutfällning tar hänsyn till andra utfällningskomplex och dess interaktioner. Inom gruvvatten industrin har det forskats en del kring olika neutralisationsmetoder, en i litteraturen föreslagen sådan är ”High Density Sludge process (HDS)”. Här återförs en del av slammet tillbaka till neutralisationssteget, vilket visade sig ge förbättrade slamegenskaper och minskad kalkåtgång. Det var intressant att undersöka om denna metod också gick att implementera på förbrukade betbad och därför prövades metoden i den experimentella delen av detta projekt. Detta gav efter ett antal återföringscykler högre torrhalt på slammet, dock krävs fortsatta undersökningar innan någon slutsats kan dras.
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Suvio, Piia. "From threat to an asset : water in steelworks : how modern steelworks can improve water related performance via benchmarking and development of High Density Sludge (HDS) Process." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/26204/.
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The Water Framework Directive (WFD) 2000/60/EC is set to overhaul the management of the water environment within the EU. Following its enforcement in 2015, changes are expected to the current water related regulations and water intensive industries, including steelworks, ought to prepare themselves for changes. In 2007 Corus Group was taken over by Tata Steel, now one of the World’s top 10 steel producers with its production of 31 MTPA (million tonnes per annum of crude steel). Tata Steel Port Talbot Integrated Steelworks is one of Tata Steel’s main sites, currently producing some 4.33 MTPA (in 2007) of crude steel (slab) and is a major user of water with its 8 production facilities and supporting functions. From 2007 to 2011 the author worked as a core member of the World Steel Association Water Management Project. The project included development of a survey to gather water-related data from the World’s steelworks. 29 steelworks took part in the survey and using the data, an extensive assessment of water related performance in steelworks around the World has been carried out. The findings show that water performance related figures, including water use and effluent generation, vary from under 1 to near 150 m3/ts. The average consumption figure being 28.4 m3/ts with once-through cooling using an average 82% of this water. The average effluent discharge figure is 25.4 m3/ts. For Port Talbot Steelworks these figures are 33.8 m3/ts and 28.8 m3/ts respectively. An investigation into effluent treatment technologies and efficiencies included carrying out chemical precipitation and co-precipitation titration experiments, especially looking at zinc, in order to better understand the behaviour of relevant metals during hydroxide precipitation reactions. The experimental results were compared against PHREEQCi theoretical geomodelling precipitation prediction data and PHREEQCi 2 indicated minimum zinc solubility is received at pH 9.5. Laboratory experiments support this. Iron enhances zinc precipitation strongly via co-precipitation. A similar effect, although to a lesser extent, is achieved for zinc co-precipitation with nickel and lead. The author’s study of the Port Talbot water systems established that the chemical precipitation processes in operation leads to the generation of voluminious sludge that is hard to dewater further. This prompted the initiation of an investigation into the suitability of the High Density Sludge (HDS) process in treating high volume, non-acidic low metal concentration effluents, such as steelworks final effluent. Prior to this research the HDS process has been used mainly for the treatment of mine effluents and its suitability in treating non-acidic, low metal concentration effluent has not been fully explored. During the trial, a 10 L/h influent feed rate was aimed for with a half hour retention time at the first two reactors. The flocculant feed rate was around 2.5-3 mg/l of treated effluent throughout the trial. At the end of the trial the sludge concentrations exceeded 17% (w/w), while the treatment efficiencies of zinc and other metals stabilised and improved. Furthermore, the sludge was behaving as HDS sludge achieving high settling rates in excess of 22 m/h at 5% (w/v). Solids concentrations and sludge filterability had improved with the specific cake resistance reducing from the ‘single pass’ precipitation sludge near 35,000 Gm/kg to the 777 Gm/kg after 2 weeks of trial to a mere 169 Gm/kg at the end of the HDS trial.
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Hynaux, Amélie. "Synthèse et caractérisation de carbures de molybdène supportés sur composite de noir de carbone mésoporeux : application en hydrodésulfuration du dibenzothiophène et en hydrodésazotation de l'indole." Paris 6, 2005. http://www.theses.fr/2005PA066096.
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Krebs, Emmanuel. "Modélisation moléculaire ab initio des effets de morphologie en catalyse par les sulfures." Paris 6, 2008. http://www.theses.fr/2008PA066174.
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L'un des procédés catalytiques du raffinage du pétrole, essentiel pour l'obtention de carburants propres (essence) vise à sélectivement hydrodésulfurer (HDS) les molécules soufrées (thiophènes) en évitant l’hydrogénation des molécules oléfiniques (HydO), afin de préserver l’indice d’octane des essences. La phase active des catalyseurs d'HDS est composée d'une phase disulfure de molybdène (MoS2), promue par du Co ou du Ni, et appelée "Co(Ni)MoS". La compréhension à l'échelle moléculaire de l’origine de la sélectivité HDS/HydO est l'enjeu de cette thèse. A l'aide de la modélisation moléculaire ab initio couplé à des modèles thermodynamiques, nous étudions premièrement la nature des sites actifs et la morphologie des phases Co(Ni)MoS en milieu réactionnel (HDS). Nous proposons, ensuite, une interprétation de la sélectivité HDS/HydO basée sur l'adsorption sélective de deux réactifs modèles (thiophénique et oléfinique) en fonction des conditions d'HDS. Le rôle clef des promoteurs est mis en évidence. Une interprétation électronique de l'adsorption des molécules est fournie.
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Silva, Neto Alano Vieira da. "Catalisadores de Mo suportados sobre sílica, sílica-titânia ou sílica-zircônia promovidos por Co ou Ni : avaliação do método de preparação e da composição do suporte na atividade para HDS." Universidade Federal de São Carlos, 2012. https://repositorio.ufscar.br/handle/ufscar/3913.
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Previous issue date: 2012-04-30Universidade Federal de Sao Carlos
Hydrodesulfurization (HDS) catalysts containing Mo, NiMo or CoMo were supported on silica, silica-titania and silica-zirconia. These supports were synthesized by the sol-gel method, using citric acid as an agent to pore formation and to complex Ti and Zr. The incorporation of the precursor salts of the active phases was done during the sol-gel preparation of the different supports (in situ addition) or by impregnation using citric acid as chelating agent. The catalysts in the oxide form were characterized by atomic absorption spectroscopy (AAS), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), temperature-programmed desorption of NH3 (TPD-NH3), Fourier Transform infrared spectroscopy (FTIR), thermogravimetric (TG) and differential thermal analysis (DTA), N2 adsorption/desorption, diffuse reflectance UVVis spectroscopy (DRSUV-Vis), temperature-programmed reduction with H2 (TPR-H2) and evaluated from 240 to 300°C in the HDS of thiophene used a model molecule. Supports and catalysts showed high specific surface area and pore volume as result of the use of citric acid in the preparation of the respective sol-gel mixtures. From XRD data was evident that the citric acid promoted a high dispersion of Ti and Zr in the silica framework, because was not observed XRD peaks related to separated phases of those metals. The XRD patterns of the catalysts did not show diffraction peaks related to other species or oxides of Mo, Co or Ni, behavior that was attributed to the high dispersion of these metal species in the different supports that was confirmed by DRSUV-Vis and H2-TPR. The HDS reaction of thiophene on NiMo and CoMo catalysts showed a higher activity for the first ones, which were more active when supported on silica or silica-zirconia. This result was attributed to the higher interaction of Ni with Mo, which generated a higher degree of reducibility of the Mo species, facilitating the subsequent sulphidation process and consequently favoring the formation of the NiMoS phase, which is indicated as the main responsible of the catalyst activity in the HDS process. The lower activity of the catalysts supported in situ on SiO2-TiO2, was related to the formation of separated phases of Mo and Ni or Co sulfides, which are less active to the HDS reaction.
Catalisadores de hidrodessulfurização (HDS) contendo Mo, NiMo ou CoMo foram suportados sobre sílica, sílica-titânia e sílica-zircônia. Esses suportes foram sintetizados via sol-gel, utilizando ácido cítrico como agente formador de poros e complexante dos metais Ti e Zr. A incorporação dos sais precursores das fases ativas foi realizada durante a preparação sol-gel dos diferentes suportes (adição in situ) ou por impregnação utilizando ácido cítrico como agente quelante. Os catalisadores na forma de óxidos foram caracterizados por espectrofotometria de absorção atômica, espectroscopia dispersiva de raios X (EDX), difração de raios X (DRX), termodessorção programada de amônia (TPD-NH3), espectroscopia no infravermelho médio (FTIR), termogravimetria (TG) e análise térmica diferencial (ATD), adsorção/dessorção de nitrogênio, espectroscopia por refletância difusa no ultravioleta visível (DRSUV-Vis), redução com hidrogênio à temperatura programada (RTP-H2) e avaliados de 240 a 300°C no HDS do tiofeno utilizado como molécula modelo. Os suportes e catalisadores apresentaram área superficial específica e volume de poros altos como resultado da utilização de ácido cítrico na preparação das respectivas misturas sol-gel. Dados de DRX evidenciaram que o ácido cítrico promoveu uma alta dispersão de Ti e Zr na rede da sílica, não se verificando a formação de fases separadas relacionadas a esses metais. Os difratogramas dos catalisadores não apresentaram picos de difração referentes aos óxidos ou outras espécies de Mo, Co ou Ni, comportamento que foi atribuído a uma alta dispersão dessas espécies nos diferentes suportes, que foi confirmada por DRSUV-Vis e RTPH2. A reação de HDS do tiofeno sobre os catalisadores NiMo e CoMo, mostrou que os primeiros apresentaram maior atividade, sendo os mais ativos os suportados in situ sobre sílica ou sílica-zircônia. Esse resultado foi atribuído à maior interação do Ni com o Mo, que permitiu um maior grau de redutibilidade das espécies desse último metal, facilitando o posterior processo de sulfetação e, consequentemente, favorecendo a formação da fase NiMoS , apontada como a principal responsável pela atividade do catalisador no processo de HDS. A menor atividade dos catalisadores suportados em SiO2-TiO2 in situ foi relacionada à formação de fases separadas dos sulfetos de Mo e de Ni ou Co, que são menos ativas na reação de HDS.
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Steiner, Petr. "Kinetic and Deactivation Studies of Hydrodesulfurization Catalysts." Doctoral thesis, Norwegian University of Science and Technology, Department of Chemical Engineering, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-94.
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Hydrodesulfurization is an important part of the hydrotreating process. More stringent regulations on the quality of fuels bring new requirements to the catalytic processes. The removal of sulfur has become a key issue in the oil refining and this work aims to address several aspects of the process.
Kinetic studies of the hydrodesulfurization reaction over conventional (molybdenum-based) and new (Pt/Y-zeolite) catalysts are reported. The hydrodesulfurization of both the real oil (light gas oil from Statoil Mongstad refinery) and model compounds (thiophene and dibenzothiophene) over a NiMo/γ-Al2O3 catalyst were studied. In a high-pressure study of the light gas oil, substituted alkyl-DBTs were found to be the most difficult to desulfurize and the order of reactivity was found to be DBT > 4-MDBT > 4,6-DMDBT. Steric hindrance together with electronic effects were identified as possible reasons for this behavior. The difference in reactivities of the individual compounds was found to decrease with the increasing reaction temperature. A gas chromatograph equipped with the atomic emission detector (GC-AED) was used for the analysis of the individual components of the oil.
The initial deactivation and the steady-state kinetics were studied during the HDS of thiophene at atmospheric pressure. Unpromoted Mo/γ-Al2O3, CoMo/γ-Al2O3, NiMo/γ-Al2O3, and phosphorus modified NiMo/γ-Al2O3 were used for the deactivation study, while NiMo/γ-Al2O3,CoMo/γ-Al2O3, and Pt/Y-zeolite (with three different pretreatments) were used for the steadystate study. Several experiments related to the deactivation of Mo/γ-Al2O3 and NiMo/γ-Al2O3 catalysts prepared with the chelating agent (NTA) were also performed and NTA was found to have no significant effect on the activity of the catalysts.
In the deactivation study, a fast initial decrease in the activity was observed on all the catalysts. However, nickel promoted catalysts were found to be more resistant to deactivation than unpromoted ones. The presence of phosphorus slightly increased the activity of the catalyst towards the thiophene HDS, but had no effect on the deactivation behavior. Several methods to regenerate the catalyst were investigated. During the resulfiding experiments, a difference between Mo/γ-Al2O3 and NiMo/γ-Al2O3 was observed. Deactivation of the Mo catalyst was more severe with increasing temperature, while for the NiMo catalyst the opposite behavior was observed. Carbon deposition on catalysts followed the similar trend: More carbon was observed on the Mo catalyst at higher temperatures, while the opposite is true for NiMo. The restoration of the activity of NiMo was complete, while the reactivation of the Mo catalyst was only partial. The results from the reactivation experiments with pure H2 and inert gas (helium) suggest that several mechanisms of the restoration of activity exist: Resulfiding of the desulfided active sites, hydrogenation and removal of the deposited carbonaceous species, and the desorption of the reactants and products from the active sites of the catalyst. Based on the observed results, the higher hydrogenation activity of nickel is assumed to be the reason for the behavior. Hydrogenation causes the faster removal of the deposited carbonaceous species and this leads to the conclusion that the desulfiding of the active sites and the adsorption of the reaction species is significantly less pronounced on the NiMo/γ-Al2O3 catalyst.
Characterization studies show differences between standard and NTA-based catalysts. The higher amount of carbon on the NTA catalysts is attributed to the presence of the carboncontaining precursor - NTA. The changes in the surface area and the pore volume were observed only during the sulfiding process. In the case of standard catalysts the surface area and the pore volume decreased, while for the NTA-based catalysts the opposite is true. No change in the surface area and the pore volume with the increasing time on stream indicates that the deactivation is not due to structural changes of the catalyst. The amount of sulfur was found to be constant during the time on stream for all the catalysts.
In the steady-state study of the HDS of thiophene, CoMo and NiMo catalysts were found to be equally active. The activity of the Pt/Y-zeolite catalyst was found to be comparable to conventional catalysts when based on the amount of active material, but a fast deactivation was observed. The product selectivities during the HDS of thiophene were found to be the same for all standard catalysts, but slightly different for the Pt/Y-zeolite catalyst. This was attributed to a higher hydrogenation activity of the Pt/Y-zeolite catalyst.
The inhibition effect of other sulfur compounds and aromatics on the high-pressure hydrodesulfurization of dibenzothiophene (DBT), the so-called “matrix effect” was studied. Thiophene and DMDS have the same inhibiting effect on the total conversion of DBT, but differences exist in the effect on the selectivities of the products at low concentrations. The results indicate that the inhibiting effect of H2S on the direct desulfurization route is stronger than the effect of thiophene on the hydrogenation pathway. In the study of aromatics, both toluene and naphthalene affect the total conversion of DBT. Naphthalene was found to be a much stronger inhibitor and inhibits mainly the direct desulfurization pathway, while the hydrogenation route is more affected by the presence of toluene.
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Sayeed, Yeasmin. "Child Marriage, Human Development and Welfare : Using Public Spending, Taxation and Conditional Cash Transfers as Policy Instruments." Doctoral thesis, Örebro universitet, Handelshögskolan vid Örebro Universitet, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:oru:diva-47122.
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The theme of this thesis is to analyze the impact of policy interventions such as financing human development (HD), tax reform and conditional cash transfer programmes, under the framework of growth and sustainable development. These policy instruments are evaluated through the application of both partial and general equilibrium models, and the last paper concentrates on developing regional social accounting matrices (SAMs) as a core database for spatial general equilibrium modelling. Essay 1: Trade-offs in Achieving Human Development Goals for Bangladesh investigates the benefits and costs associated with alternative investment financing options for achieving HD goals by applying the MAMS (Maquette for Millennium Development Goals Studies) model. We find that full achievement of these goals would have led to a GDP loss that would have been significantly larger in the domestic borrowing scenario than in the tax scenario. The tax-financing alternative is thus the better option for financing large development programs. In terms of public spending composition, we find that, under some circumstances, a trade-off arises between overall Millennium Development Goal (MDG) progress and poverty reduction. Essay 2: Welfare impact of broadening VAT by exempting Small-Scale food markets: The case of Bangladesh analyses the welfare impacts of different VAT reforms. A general and uniform VAT on all commodities is preferred as it is more efficient and less administratively costly. However, due to equity concerns, food is normally exempted from VAT. On the other hand, exemptions on food mean that an implicit subsidy is provided to high-income households. Hence, we analyze a broad-based VAT regime with a high threshold that excludes small-scale operators (where the low-income households buy their products most, including food) and the simulation result shows that welfare improves for the low-income households. Essay 3: Effect of Girls’ Secondary School Stipend on Completed Schooling and Age at Marriage: Evidence from Bangladesh estimates the effect of a conditional cash transfer programme on education and age at marriage. We apply both difference in differences (DiD) and regression discontinuity methods to evaluate the impact of the policy instrument. Our estimation results show that the girls in the treatment group who were exposed to the programme had a higher average number of completed years of schooling and also delayed their first marriage compared to the girls in the control group. We also show that the DiD approach might produce a biased result as it does not consider the convergence effect. Essay 4: Estimation of Multiregional Social Accounting Matrices using Transport Data proposes a methodology for estimating multiregional SAMs from a national SAM by applying the cross-entropy method. The methodology makes possible the construction of regional SAMs that are consistent with official regional accounts and minimize deviations from transport data.
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Nyström, Simon, and Joakim Lönnegren. "Processing data sources with big data frameworks." Thesis, KTH, Data- och elektroteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-188204.
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Big data is a concept that is expanding rapidly. As more and more data is generatedand garnered, there is an increasing need for efficient solutions that can be utilized to process all this data in attempts to gain value from it. The purpose of this thesis is to find an efficient way to quickly process a large number of relatively small files. More specifically, the purpose is to test two frameworks that can be used for processing big data. The frameworks that are tested against each other are Apache NiFi and Apache Storm. A method is devised in order to, firstly, construct a data flow and secondly, construct a method for testing the performance and scalability of the frameworks running this data flow. The results reveal that Apache Storm is faster than Apache NiFi, at the sort of task that was tested. As the number of nodes included in the tests went up, the performance did not always do the same. This indicates that adding more nodes to a big data processing pipeline, does not always result in a better performing setup and that, sometimes, other measures must be made to heighten the performance.Big data är ett koncept som växer snabbt. När mer och mer data genereras och samlas in finns det ett ökande behov av effektiva lösningar som kan användas föratt behandla all denna data, i försök att utvinna värde från den. Syftet med detta examensarbete är att hitta ett effektivt sätt att snabbt behandla ett stort antal filer, av relativt liten storlek. Mer specifikt så är det för att testa två ramverk som kan användas vid big data-behandling. De två ramverken som testas mot varandra är Apache NiFi och Apache Storm. En metod beskrivs för att, för det första, konstruera ett dataflöde och, för det andra, konstruera en metod för att testa prestandan och skalbarheten av de ramverk som kör dataflödet. Resultaten avslöjar att Apache Storm är snabbare än NiFi, på den typen av test som gjordes. När antalet noder som var med i testerna ökades, så ökade inte alltid prestandan. Detta visar att en ökning av antalet noder, i en big data-behandlingskedja, inte alltid leder till bättre prestanda och att det ibland krävs andra åtgärder för att öka prestandan.
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Lesage, Clément. "Caractérisation par Quick-XAS operando du rôle de l’additif organique sur le mécanisme de sulfuration en phase liquide des catalyseurs d’hydrotraitement." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS565.
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Pour répondre aux normes environnementales relatives à la teneur en soufre des carburants pétroliers et optimiser l’éco-efficience des procédés d’hydrotraitement, un des leviers consiste à mettre au point des catalyseurs de plus en plus performants. Ces dernières années, l’amélioration des performances catalytiques a été possible notamment par l’ajout d’additifs organiques dont le rôle est d’améliorer la dispersion des phases oxydes sur le support catalytique et/ou de complexer les métaux pouvant conduire à leur sulfuration simultanée et favoriser ainsi la formation de catalyseurs plus actifs. Avant son utilisation, le catalyseur peut être activé selon deux méthodes. La première méthode en phase gaz (H₂S/H₂, 1 bar) a largement été utilisée en laboratoire pour étudier l’effet des additifs organiques. Cependant, la seconde méthode en phase liquide (Gazole/H₂/DMDS) sous pression (30 bar) et à 350°C est celle utilisée industriellement. Pour étudier en détail le mécanisme de sulfuration in situ en conditions industrielles des catalyseurs d’HDT additivés, une cellule d’analyse Quick-XAS permettant de reproduire ces conditions opératoires a été développée et validée sur la ligne ROCK du synchrotron SOLEIL. Le Quick-XAS est en effet une technique de choix pour caractériser la structure des phases actives formées pendant cette étape d’activation et ainsi mettre en évidence le rôle des additifs (acide citrique, triéthylène glycol et acide thioglycolique). Cette étude nous a permis d’apporter de nouvelles connaissances pour expliquer les modifications apportées à la phase active pendant la sulfuration en phase liquide et leur effet sur les performances catalytiques. En complément, le couplage des spectroscopies Raman et d’absorption des rayons X mises en œuvre sur les catalyseurs oxydes a permis une meilleure compréhension du rôle des additifs organiques étudiés dès l’étape de synthèse des solidesTo meet the environmental standards on the sulfur content in fuels and improve the eco-efficiency of hydrotreatment processes, one lever is to develop more and more efficient catalysts. In the last years, the improvement of catalytic performances has been made possible by the addition of organic additives whose role is to improve the dispersion of the oxide precursors on the support and/or create a complex with the metals, which could lead to a simultaneous sulfidation and to a more active catalyst. Before its use, the catalyst may be activated via two different methods. The first one with a gas mixture (H₂S/H₂, 1 bar), was largely used at the laboratory scale to study the effect of organic additives. However, the second activation method with a liquid phase (Gasoil/H₂/DMDS) under 30 bar at 350°C is the one used at the industrial scale. To study in situ the sulfidation mechanism of additivated HDT catalysts in industrial conditions, a Quick-XAS analytical cell was developed and validated on the ROCK beamline at the SOLEIL synchrotron. Quick-XAS is a technique of choice to characterize the formation of the active phase during the activation procedure and therefore evidence the role of organic additives (citric acid, triethyleneglycol, thioglycolic acid). This study has provided us with new knowledge to explain the changes observed in the active phase during liquid phase sulfidation and their effect on catalytic performance. In addition, coupling the Raman spectroscopy and the absorption spectroscopy to study the oxide phase has led to a better understanding of the role of the organic additives studied from the solid synthesis stage
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Verma, Anshuman. "On the Programmability and Performance of OpenCL Designs for FPGA." Thesis, Virginia Tech, 2018. http://hdl.handle.net/10919/92699.
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Field programmable gate arrays (FPGAs) have been emerging as a promising bedrock to provide opportunities for several types of accelerators that spans across various domains such as finance, web-search, and data center networking, among others. Research interests facilitating the development of accelerators on FPGAs are increasing significantly, in particular, because of their effectiveness with a variety of applications, flexibility, and high performance per watt. However, several key challenges remain that hinder their large-scale deployment. Overcoming these challenges would enable them to match the pervasiveness of graphics processor units (GPUs), their principal competitors in this arena. One of the primary reasons responsible for the slow adaptation by programmers has been the programming model, which uses a low-level hardware description language (HDL).
Using HDLs require a detailed understanding of logic design and significant effort to implement and verify the behavioral models, with the latter growing with its complexity. Recent advancements in high-level language synthesis (HLS) tools have addressed this challenge to a considerable extent by allowing the programmers to write their applications in a high-level language named OpenCL. These applications are then compiled and synthesized to create a bitstream that configures the FPGA. This thesis characterizes the efficacy of HLS compiler optimizations that can be employed to improve the performance of these applications.
The synthesized hardware from OpenCL kernels is fundamentally different from traditional hardware such as CPUs and GPUs, which exploit instruction level parallelism (ILP) thread level parallelism (TLP), or data level parallelism (DLP) for performance gains. FPGAs typically use deep pipelining (i.e., ILP) for performance. A stall in this pipeline may severely undermine the performance of applications. Thus, it is imperative to identify and remove any such bottlenecks. To this end, this thesis presents and discusses a software-centric framework to debug and profile the synthesized designs generated using HLS tools. This thesis proposes basic code patterns, including a timestamp and a scalable framework, which can be plugged easily into OpenCL kernels, to collect and process run-time information dynamically. This scalable framework has a small overhead for area utilization and frequency but provides fine-grained information about the bottlenecks and latencies in design.
Additionally, although HLS tools have improved programmability, this may come at the cost of performance or area utilization. This thesis addresses this design trade-off via a comparative study of a hand-coded design in HDL and an architecturally similar, tool-generated design using an OpenCL compiler in the application area of 3D-stencil (i.e., structured grid) computation. Experiments in this thesis show that the performance of an OpenCL approach can achieve 95% of the peak attainable performance of a microkernel for multiple problem sizes. In comparison to the OpenCL approach, an HDL approach results in approximately 50% less memory usage and only 2% better performance on average.MS
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Bhat, Adithya. "RDMA-based Plugin Design and Profiler for Apache and Enterprise Hadoop Distributed File system." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1440188090.
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Zelenková, Jana. "Přístupy k měření chudoby se zaměřením na členské státy EU." Master's thesis, Vysoká škola ekonomická v Praze, 2014. http://www.nusl.cz/ntk/nusl-201951.
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This thesis focuses on current approaches to the measurement of poverty. The aim of the thesis is to evaluate if measuring poverty indicators and quality of life indicators used by United Nations Development Programme and Eurostat are meaningful enough. The theoretical part is an analysis of chosen indicators. The theoretical knowledge is followed by practical part, comparing poverty levels in member states of the European Union, and giving deeper insight into the analysis of sub-indicators. Furthermore, the thesis looks at informative value connected to mutual relations among the indicators. The comparison reveals that the level of human development is negatively related to aspects such as insufficient economic growth, inequality and low level of wealth redistribution. From an analytical point of view, new multi-criteria indicators are useful enough for the purpose of research on this topic, in spite of certain imperfections.
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Cunha, Caroline de Andrade Gomes da. "Análise da eficiência de um sistema combinado de alagados construídos na melhoria da qualidade das águas." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/18/18139/tde-04122006-232326/.
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Este trabalho teve como objetivo avaliar a eficiência de um sistema combinado de alagados construídos, localizado no Parque Ecológico do Tietê em São Paulo, na melhoria da qualidade das águas. A estação de estudo é composta por um canal de decantação, um canal de macrófitas flutuantes (Eicchornia crassipes, Pistia stratioides, Salvinia auriculata) e emergentes (Typha angustifolia) de fluxo superficial, e duas células paralelas de solos filtrantes de fluxo vertical descendente cultivados com arroz (Oryza sativa). As coletas de água foram realizadas mensalmente, na entrada e saída de cada etapa do sistema, no período de fevereiro, março, junho e julho de 2004 e de março a setembro de 2005. As variáveis físicas, químicas e biológicas da água foram medidas e taxas de eficiência de remoção parcial e total do sistema foram calculadas. A estação construída de alagados mostrou-se eficiente principalmente na remoção de sulfato (52%), turbidez (86%), 'DBO IND.5' (41 - 64%), fósforo total (51 68%), nitrogênio albuminóide (51,7%), nitrito (77,8%) e nitrogênio amoniacal (57 84%). Os canais de macrófitas apresentaram um alto desempenho de remoção média para maioria das variáveis analisadas no trabalho, contribuindo com a maior porção na taxa de remoção total do sistema. Durante o período de estudo, provavelmente devido à falta de manejo do sistema, observou-se a volta dos nutrientes assimilados pelas macrófitas para a coluna d`água (N, P, Fe) com a decomposição das plantas e condições de anaerobiose nos solos filtrantes. Esses fatores, juntamente com a presença dos animais do parque atraídos pelo arroz, contribuíram com o baixo desempenho do canal de macrófitas e dos solos filtrantes na remoção de cor, turbidez, ferro total e coliformes em alguns meses de coleta. Para a maioria das variáveis analisadas, a água tratada pelo sistema de alagados construídos alcançou os limites e padrões estabelecidos pela Resolução CONAMA 357/2005 para águas doces de classe 2 (BRASIL, 2005). Contudo, em função dos dados obtidos, não se pode enquadrar totalmente o efluente, embora seja esperado que com a estabilização do sistema e um manejo adequado, a água tratada consiga atingir as características exigidas e possa ser enquadrada em águas doces de classe 2.The aim of this work was evaluate the efficiency of combined constructed wetlands, located in the Tiete Ecological Park in São Paulo, in water quality improvement. The station consists of a settling channel, one free-floating (Eichhornia crassipes, Salvinia auriculata, Pistia stratiotes) and rooted emergent macrophyte-based system (Typha angustifolia) with surface flow and two cells of vertical flow filter soils in parallel, planted with rice (Oryza sativa). The water samples were collected monthly at the inlet and outlet of each step of the system, in the period of February, March, June and July of 2004 and of March to September of 2005. The physical, chemical and biological variables of the water were measured and efficiency rates of the system were made. The constructed wetlands system mainly showed efficient removal rates in sulphate (52%), turbidity (86%), BDO (41 - 64%), total phosphorus (51 - 68%), organic nitrogen (51,7%), nitrite (77,8%) and ammonia nitrogen (57 - 84%). The settling channel and macrophyte-based system presented a high removal performance for most of the variables analyzed in the work, contributing with the largest portion in the total removal rate of the system. During the study period, probably due to the lack of system management, the return of nutrients previously uptaken (N, P, Fe) by macrophytes for the water column was observed with the decay of aging plants and anaerobic conditions in the HDS system. Those factors, added with the presence of the park´s animals attracted for the rice, contributed with the low performance of macrophyte-based and HDS system in the removal of color, turbidity, total iron and coliforms in some months of collection. For most of the analyzed variables, the water treated by the constructed wetlands system reached the limits and patterns established by the Resolution CONAMA 357/2005 for fresh water of class 2 (BRAZIL, 2005). However, due to the obtained data, the treated water cannot be totally classified as class 2, although it is expected that with the stabilization of the system and appropriate handling, the treated water reach the demanded characteristics and can be classified in fresh water of class 2.
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Nosko, Svetozár. "Akcelerace HDR tone-mappingu na platformě Xilinx Zynq." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2016. http://www.nusl.cz/ntk/nusl-255329.
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This diploma thesis focuses on the High-level synthesis (HLS). The first part deals with theoretical details and methods that are used in HLS tools. This is followed by a description of the synthesis tool Vivado HLS which will be used for implementation of an application. In the second part is briefly introduced high dynamic range images (HDR) and tone mapping. The third part is dedicated to design and implementation of the aplication which implements tone mapping methods in HDR images. This methods are implemented in Vivado HLS and language C++. This application is based on platform Xilinx Zynq and it uses multiexposure camera for capturing HDR images. Images are transmitted to FPGA for tone mapping processing.
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Vasconcelos, Sebastião Junior Teixeira. "Catalisadores derivados de hidrotalcita dopados com cobre na transformação química do glicerol." reponame:Repositório Institucional da UFC, 2014. http://www.repositorio.ufc.br/handle/riufc/20116.
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VASCONCELOS, Sebastião Junior Teixeira. Catalisadores derivados de hidrotalcita dopados com cobre na transformação química do glicerol. 2014. 70 f. Dissertação (Mestrado em química)- Universidade Federal do Ceará, Fortaleza-CE, 2014.Submitted by Elineudson Ribeiro (elineudsonr@gmail.com) on 2016-10-11T18:03:43Z No. of bitstreams: 1 2014_dis_sjtvasconcelos.pdf: 2964927 bytes, checksum: bb81ba47076b4718708588b791e60c4e (MD5)
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The hydrotalcites are a class of layered double hydroxides with important physical and chemical properties. The use of this class of compounds in catalysis of specific reactions also requires many studies. The literature has exploited these materials in catalytic reactions in liquid phase with glycerol, particularly in hydrogenolysis reactions. The gas phase reactions with glycerol usually make use of acid catalysts. Thus, both the liquid phase reactions involving catalysts derived from hydrotalcite-like gas phase reactions involving basic catalysts require further study. We developed a study to elucidating the combined effects of basic catalytic sites (MgO and amorphous aluminum oxide) and dehydrogenation (derived from copper oxides) in the hydrogenolysis reaction. The materials used were derived from hydrotalcite oxides, and oxides derivatives containing in its composition 2.5% copper (molar ratio) in relation to the metal network hydrotalcite (Mg and Al). The results obtained for the gas phase show an interrelationship between the sites and the major products of the reaction, acetol and acrolein. Was determined conditions under which one or another product is more favored, with conversions that can reach over 90% and selectivities that exceed 99%. In the liquid phase this interrelationship is more difficult to be demonstrated, given the complications arising from the greater contact time between catalyst and reactants to the point of the major products at the reaction gas phase includes both as reaction intermediates in the liquid phase. In the liquid phase, the predominant carbon chain compounds of higher alcohol and ester functional groups, cyclic compounds but also from various functional groups.
As hidrotalcitas são uma classe de hidróxidos duplos lamelares com importantes propriedades físico-químicas. O emprego desta classe de compostos na catálise de reações específicas requer, ainda, muitos estudos. A literatura tem explorado estes materiais na catálise das reações com glicerol em fase líquida, principalmente, em reações de hidrogenólise. As reações em fase gasosa com glicerol normalmente fazem uso de catalisadores ácidos, de modo. Deste modo, tanto as reações em fase líquida envolvendo catalisadores derivados da hidrotalcita como reações em fase gasosa envolvendo catalisadores básicos requerem maiores estudos. Desenvolveu-se um estudo com vistas a elucidação dos efeitos combinados de sítios catalíticos básicos (MgO e óxidos de alumínio amorfo) e desidrogenante (óxidos derivados do cobre) na reação de hidrogenólise. Os materiais empregados foram óxidos derivados da hidrotalcita, e óxidos derivados contendo em sua composição 2,5% cobre (proporção molar) em relação aos metais da rede hidrotalcita (Mg e Al). Os resultados obtidos para a fase gasosa evidenciam uma inter-relação entre os sítios e os produtos majoritários da reação, acetol e acroleina. Determinou-se condições em que um ou outro produto é mais favorecido, com conversões que podem chegar a mais de 90% e seletividades que superam 99%. Em fase líquida esta inter-relação é mais difícil de ser evidenciada, dadas as complicações originadas pelo maior tempo de contato entre catalisador e reagentes a tal ponto dos produtos majoritários verificados na reação fase gasosa figurarem como intermediários da reação em fase líquida. Na fase líquida, predominam compostos de maior cadeia carbônica dos grupos funcionais álcool e éster, mas também compostos cíclicos de grupos funcionais diversos.
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Lukáč, Ľuboš. "Udržitelnost sociální situace obyvateľstva v období hospodářské krize." Master's thesis, Vysoká škola ekonomická v Praze, 2010. http://www.nusl.cz/ntk/nusl-72281.
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Abstract The role of the thesis is to analyze the financial situation of households and changes in living standards in Slovakia since 2000 through the creation of economic crisis to the present. In the thesis are described in detail information about unemployment, income and economically active population, but also the inflow of foreign investment, social security, household indebtedness of individuals and social situation in the Slovak Republic. These indicators compared with countries of European Union Member States. This topic is very interested because of its topicality. I chose Slovakia for two reasons. The first is that I am citizen of the Slovak Republic and the second is the availability of statistical data and work with them. Keywords: social situation, GDP, HDI, unemployment, poverty, FDI
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Vasconcelos, SebastiÃo Junior Teixeira. "Catalysts from hydrotalcite dopped with copper in chemical transformation of glycerol." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=14604.
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Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoThe hydrotalcites are a class of layered double hydroxides with important physical and chemical properties. The use of this class of compounds in catalysis of specific reactions also requires many studies. The literature has exploited these materials in catalytic reactions in liquid phase with glycerol, particularly in hydrogenolysis reactions. The gas phase reactions with glycerol usually make use of acid catalysts. Thus, both the liquid phase reactions involving catalysts derived from hydrotalcite-like gas phase reactions involving basic catalysts require further study. We developed a study to elucidating the combined effects of basic catalytic sites (MgO and amorphous aluminum oxide) and dehydrogenation (derived from copper oxides) in the hydrogenolysis reaction. The materials used were derived from hydrotalcite oxides, and oxides derivatives containing in its composition 2.5% copper (molar ratio) in relation to the metal network hydrotalcite (Mg and Al). The results obtained for the gas phase show an interrelationship between the sites and the major products of the reaction, acetol and acrolein. Was determined conditions under which one or another product is more favored, with conversions that can reach over 90% and selectivities that exceed 99%. In the liquid phase this interrelationship is more difficult to be demonstrated, given the complications arising from the greater contact time between catalyst and reactants to the point of the major products at the reaction gas phase includes both as reaction intermediates in the liquid phase. In the liquid phase, the predominant carbon chain compounds of higher alcohol and ester functional groups, cyclic compounds but also from various functional groups.
As hidrotalcitas sÃo uma classe de hidrÃxidos duplos lamelares com importantes propriedades fÃsico-quÃmicas. O emprego desta classe de compostos na catÃlise de reaÃÃes especÃficas requer, ainda, muitos estudos. A literatura tem explorado estes materiais na catÃlise das reaÃÃes com glicerol em fase lÃquida, principalmente, em reaÃÃes de hidrogenÃlise. As reaÃÃes em fase gasosa com glicerol normalmente fazem uso de catalisadores Ãcidos, de modo. Deste modo, tanto as reaÃÃes em fase lÃquida envolvendo catalisadores derivados da hidrotalcita como reaÃÃes em fase gasosa envolvendo catalisadores bÃsicos requerem maiores estudos. Desenvolveu-se um estudo com vistas a elucidaÃÃo dos efeitos combinados de sÃtios catalÃticos bÃsicos (MgO e Ãxidos de alumÃnio amorfo) e desidrogenante (Ãxidos derivados do cobre) na reaÃÃo de hidrogenÃlise. Os materiais empregados foram Ãxidos derivados da hidrotalcita, e Ãxidos derivados contendo em sua composiÃÃo 2,5% cobre (proporÃÃo molar) em relaÃÃo aos metais da rede hidrotalcita (Mg e Al). Os resultados obtidos para a fase gasosa evidenciam uma inter-relaÃÃo entre os sÃtios e os produtos majoritÃrios da reaÃÃo, acetol e acroleina. Determinou-se condiÃÃes em que um ou outro produto à mais favorecido, com conversÃes que podem chegar a mais de 90% e seletividades que superam 99%. Em fase lÃquida esta inter-relaÃÃo à mais difÃcil de ser evidenciada, dadas as complicaÃÃes originadas pelo maior tempo de contato entre catalisador e reagentes a tal ponto dos produtos majoritÃrios verificados na reaÃÃo fase gasosa figurarem como intermediÃrios da reaÃÃo em fase lÃquida. Na fase lÃquida, predominam compostos de maior cadeia carbÃnica dos grupos funcionais Ãlcool e Ãster, mas tambÃm compostos cÃclicos de grupos funcionais diversos.
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Rettore, Paulo Henrique Lopes. "Infraestrutura de compilação para a implementação de aceleradores em FPGA." Universidade Federal de São Carlos, 2012. https://repositorio.ufscar.br/handle/ufscar/510.
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Previous issue date: 2012-11-23Financiadora de Estudos e Projetos
In recent years, performance improvements in sequential microprocessors have been limited by physical and technological factors. For this reason, alternative approaches for high performance execution have gained importance. One of them is based in the use of reconfigurable hardware, implemented using FPGAs. However, conventional methods for programming those devices are notoriously complex, usually based on hardware description languages such as VHDL and Verilog. This work presents the development of a compilation framework to support the translation of a loop, described in C language, into its corresponding version for synthesis in reconfigurable hardware. The optimized execution is based on the loop pipelining technique, which requires advanced compiler support. That is achieved by using the Cetus compiler, enhanced by a number of modifications, and thus used as a basis for the semi-automatic generation of custom-hardware accelerators. In order to guide the compiler developments and validate its basic functionalities, two study cases were considered: one based on finite state machines as the method of choice for hardware modelling (EC-1), and another based on the LALP domain specific language. In both cases, the proposed compilation framework have shown to be a facilitator element for the development of high performance custom-hardware.
O aumento no desempenho de processadores sequenciais tem sido limitado severamente por fatores físicos e tecnológicos nos últimos anos. Dessa forma, abordagens alternativas para a execução com alto desempenho ganharam maior importância nos últimos anos. Uma delas baseia-se na utilização de hardware customizado, implementado utilizando-se FPGAs. Entretanto, os métodos convencionais para programação desses dispositivos são notoriamente complexos, normalmente baseados em linguagens como VHDL e Verilog. Este trabalho apresenta o desenvolvimento de um framework de compilação para auxiliar a transformação de um loop, escrito em linguagem C, em sua versão para hardware customizado. A execução otimizada baseia-se na técnica de loop pipelining, a qual exige suporte avançado de compilação. Este é conseguido utilizando o compilador Cetus, que após uma série de modificações, pode ser utilizado como base para a geração semi-automática de aceleradores em hardware customizado. Como forma de guiar o desenvolvimento do compilador e validar suas funcionalidades básicas, dois casos de estudo foram considerados: um baseado na utilização de máquinas de estados finitos como método para a modelagem de hardware (EC-1), e outro baseado na linguagem de domínio específico LALP (EC-2). Em ambos os casos, o framework de compilação proposto mostrou-se útil como elemento facilitador ao desenvolvimento de hardware customizado de alto desempenho.
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Burgisser, Alain. "HDR." Habilitation à diriger des recherches, Université d'Orléans, 2009. http://tel.archives-ouvertes.fr/tel-00447580.
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La Volcanologie moderne utilise des approches expérimentales, de terrain et théoriques pour mieux comprendre des phénomènes volcaniques critiques. Ces différents angles sont nécessaires en raison de l'extrême variation des échelles impliquées : des bulles de gaz de moins d'un millimètre libérant le gaz générant des panaches explosifs de plusieurs kilomètres de haut. La physique multiphasée, qui a pour objet d'étude l'écoulement de mixtures réactives de fluide et de particules, a permis des avancées dans l'unification de ces échelles. En combinant des lois à petite échelle, comme la croissance d'une bulle, des propriétés nouvelles émergent des simulations numériques, comme la ségrégation des bulles dans un conduit volcanique. De telles propriétés émergentes sont souvent valides à de grandes échelles et peuvent parfois être testées dans les systèmes naturels. La physique multiphasée reste cependant très jeune: les expérimentalistes qui déterminent les lois constitutives des systèmes les plus simples, les modélisateurs qui assemblent ces lois dans des modèles numériques complexes aux propriétés émergentes et les volcanologues de terrain qui mesures ces propriétés n'ont pas toujours le langage commun permettant de confronter leurs découvertes. Mes travaux ont eu pour but de trouver ce langage commun afin de faciliter l'intégration de nos connaissances sur les volcans. Cette intégration, renforcée dans le futur, pourrait ouvrir la possibilité d'unification de ces sous domaines. Allons-nous vers une unification de la Volcanologie ?
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Kremer, Laurent. "HDR." Habilitation à diriger des recherches, Université Montpellier II - Sciences et Techniques du Languedoc, 2007. http://tel.archives-ouvertes.fr/tel-00259336.
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Adams, Katherine M. "Has-Been." Digital Commons at Loyola Marymount University and Loyola Law School, 2013. https://digitalcommons.lmu.edu/etd/10.
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