Les agents chimiques de guerre et leurs dérivés pesticides sont des molécules toxiques qui provoquent une incapacité temporaire ou des dommages permanents allant jusqu’à la mort de l’individu. Une des voies majeures de la contamination est la pénétration cutanée. La protection de la peau semble donc importante pour prévenir de ces dangers. Cette thèse concerne l’élaboration de nouveaux topiques protecteurs cutanés contenant des polymères HASE fluorés greffés avec des nanoparticules de silice, cérine ou titane. Dans un premier temps les actifs ont été synthétisés en grosse quantité et leurs propriétés de mouillabilité améliorées. Les tests toxicologiques ont montré que les actifs n’étaient pas irritants pour la peau et non toxiques pour l’environnement. La formulation de ces polymères a permis le développement de deux nouvelles crèmes barrières contre la pénétration du paraoxon dont l’efficacité est dépendante de la présence des nanoparticules. Le greffage des nanoparticules à un polymère HASE fluoré et leur formulation a donc permis le développement de nouveaux topiques efficaces. L’évaluation de l’efficacité a été réalisée sur membranes artificielles et confirmée sur explants de peaux humaines. Enfin, le peu de disponibilité des explants de peaux humaines a motivé le développement d’un modèle d’efficacité utilisant des épidermes humains reconstruits. / Chemical warfare agents and pesticides are toxic molecules causing temporary incapacitation or permanent harms leading to the death of people. One of the major routes of contamination is the percutaneous penetration. Skin protection is important to prevent these dangers. The aim of this thesis is to develop new active topical skin protectants based on nanoparticular networks containing fluorinated HASE polymers grafting with silica, cerium or titanium nanoparticles. First, polymers were synthesized in larger quantity and their wettability properties improved. Toxicological studies have showed that these compounds are non-irritant and non-toxic for the environment. The formulation of these polymers has led to the elaboration of two new barrier creams against paraoxon penetration whose efficiency is dependent on the presence of nanoparticles. Therefore, the grafting of nanoparticles to fluorinated HASE polymer and their formulation have enabled the development of new active topical skin protectant. Efficiency evaluation was done using artificial membranes and was confirmed on ex vivo human skin. The limited availability of human skin explants has motivated the development of a new efficiency model using reconstructed human epidermis.

The depletion of fossil fuels together with growing environmental concerns have created incitement for developing a more energy-efficient and environmentally-friendly vehicle fleet. The development towards cleaner heavy-duty vehicles started already in the 80’s with the introduction of emission legislations. Initially, engine optimization was enough for reaching the legislated levels of emissions. However, at present engine optimization is not enough but exhaust aftertreatment has become an essential part of heavy-duty vehicles, in order to meet the emission standards. Today, the total emissions are targeted which means that there is an interest in decreasing the idling emissions as well as the emissions during operation. To reduce the overall emissions several states in the USA have introduced idling legislations. Due to the limitations in idling time alternative solutions for power generation during rests are requested. A possible alternative is a fuel cell auxiliary power unit, combining a fuel cell with a fuel reformer (FC-APU).  The focus of this thesis is the development of the fuel reformer for an FC-APU, in which the hydrogen to the fuel cell is generated from diesel in a high-temperature catalytic process. The produced hydrogen can also be used in other heavy-duty vehicle applications i.e. selective catalytic reduction of NOx (HC-SCR), where addition of hydrogen is essential for reaching high conversion at low temperatures. The effect of using hydrogen from a fuel reformer in HC-SCR is included in this work. The catalytic material development is focused on developing promoted materials with lower rhodium content but with catalytic activity comparable to that of materials with higher rhodium content. This includes evaluation and extensive characterization of both fresh and aged promoted materials. The work also includes reactor design where a micro reactor with multiple air inlets is evaluated. This work has contributed to increased knowledge of catalytic materials suitable for reforming of diesel. By changing the support material from the traditionally used alumina to ceria-zirconia, increased H2 yield was achieved. In addition, the ceria-zirconia supported material was less prone to coke. By promoting the material with cobalt or lanthanum it was possible to decrease the rhodium content by 2/3 with enhanced catalytic performance. It was also discovered that promotion with lanthanum decreased the tendency for coking even further. Additionally, the lanthanum-promoted material had higher thermal stability as well as a stable highly dispersed rhodium phase. Furthermore, the work has contributed to an increased knowledge concerning the fuel reformer’s effect on HC-SCR. The work displays clear evidence of benefits with using hydrogen-rich gas from a fuel reformer instead of pure hydrogen. The benefits are derived from the content of low molecular weight hydrocarbons present in the hydrogen-rich gas, which are strong reducing agents increasing the NOx reduction. This finding proves that fuel reforming in combination with HC-SCR is a viable option for NOx abatement. / <p>QC 20150202</p>

Pesquisas realizadas em todo o mundo exploram a possibilidade de utilizar o hidrogênio como combustível para a geração de energia, já que ele produz a chamada \"energia limpa\". O hidrogênio pode ser obtido a partir das reações de reforma de etanol, fonte renovável, em contraste com o clássico processo de obtenção a partir de derivados de petróleo. Desta forma, há um crescente interesse em pesquisa e desenvolvimento de catalisadores eficientes para gerar hidrogênio. Assim, no presente trabalho foram estudados catalisadores de ródio contendo 0,5; 1 e 3% (m/m) suportados em CeO2, Al2O3 e 20%CeO2- Al2O3 nas reações de reforma a vapor de etanol (RVE) e reforma oxidativa de etanol (ROE) visando a geração de hidrogênio. As amostras foram preparadas pelo método de impregnação úmida e caracterizadas por difração de Raios-X (XRD), área superficial específica - método B.E.T., espectroscopia dispersiva em emissão de Raios-X (EDX), espectroscopia de fotoelétrons excitada por Raios-X (XPS), espectroscopia na região do ultra-violeta e do visível (UV-vis- NIR) e redução à temperatura programada (RTP-H2). Os ensaios catalíticos, realizados entre 400 e 600ºC, mostraram altas conversões de etanol para todos os catalisadores. As maiores produções de H2, a partir das reações de RVE e ROE, foram obtidas à 600ºC com os catalisadores Rh/CeO2 e Rh/20%CeO2-Al2O3. Foi observado que a adição de oxigênio proporcionou um aumento na produção de H2, bem como na razão CO2/CO e nas deposições de carbono. / The researches made in the world explore the possibility in the use of hydrogen like a fuel for energy generation, since it produces the called \"clean energy\". The hydrogen can be obtained through of the ethanol reforming reaction, i.e. renewable source, in contrast with the classical process for obtaining from petroleum derivates. In this way, there is a crescent interest in research and development of efficient catalysts in order to obtain hydrogen. Thus, in this work were studied the rodium catalysts with 0,5; 1 e 3% (w/w) supported on CeO2, Al2O3 e 20%CeO2-Al2O3 for the ethanol steam reforming (ESR) and oxidative reforming (EOR) reactions aiming to the hydrogen generation. The samples were prepared by wet impregnation method and characterized by X-ray diffraction (XRD), specific superficial area - BET method, energy dipersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy (UVvis), and temperature-programmed reduction (TPR-H2). In according to the catalytic tests, performed between 400 and 600ºC, it was obtained higher ethanol conversion values for all catalysts. The highest H2 yield it was obtained at 600ºC, with the Rh/CeO2 e Rh/20%CeO2-Al2O3 catalysts. It was observed that the addition of oxygen caused an increase in H2 production, as well as, in the CO2/CO ratio and in the carbon deposition.

No description available.

Grâce à leurs propriétés particulières dues à leur petite taille, les nanomatériaux (dimension < 100 nm) sont utilisés dans de nombreuses applications grand public (cosmétique, matériaux nanostructurés,...). Cependant, leur présence grandissante inquiète car leur impact potentiel sur les humains et l'environnement reste mal connu. Cette étude est consacrée à une compréhension approfondie des interactions physicochimiques et biologiques entre deux modèles cellulaires présents dans l'environnement : Synechocystis (cyanobactérie contribuant au maintien de la biosphère) et Escherichia coli (bactérie des intestins des mammifères) avec des nanoparticules d'oxyde de cérium (abondance environnementale croissante, ex : additif au diesel). <br />La complexité de l'étude des nanoparticules nécessite une approche différente (multidisciplinaire) de celle des tests de toxicité utilisés pour les composés classiques. En effet, nous montrons que les paramètres physicochimiques (stabilité, agrégation, dissolution et état de surface) des nanoparticules dans le milieu de contact, influencent fortement la toxicité observée sur les cellules. De plus, les interactions physicochimiques (floculation, adsorption, mécanismes redox) sont liées au modèle biologique, en particulier à la présence d'exopolysaccharides (chez Synechocystis) comme barrière naturelle entre la paroi cellulaire et les nanoparticules. La composition du milieu de dispersion des nanoparticules (notamment son pH) a aussi une influence majeure sur la toxicité (survie et intégrité membranaire). Tandis que pour E. coli, ce sont majoritairement les nanoparticules qui provoquent la mortalité (confirmé par analyses métabonomiques par RMN).

The fate and transformation of laboratory-prepared nano-ZnO, nano-Ag and nano-CeO2 in three aqueous solutions under different environmental conditions were investigated in this work. Over the past decades nanomaterials have been widely used in different technical fields and consumer goods. As a result, nanomaterials might enter the environmental media via different routes and then posed potential hazards to the environment and human health. Researches in this regard have received much attention worldwide. In this work it was found that the solubility of each nanomaterial was highly influenced by the solution pH, but not by the solution temperature. The maximal solubility for the tested nanomaterials was obtained at pH 3, namely about 100% for nano-ZnO and lower than 2% for both nano-Ag and nano-CeO2. The solution pH and ionic strength were found to affect the stability of nanoparticles in different aquatic environments. For the solution pH of higher than the isoelectric point of the concerned nanomaterial, the higher the solution pH is, the greater the degree of stabilization of nanoparticles would be. On the contrary, nanoparticles aggregated as the ionic strength of the solution exceeded its critical aggregation concentration (CAC). CAC for each concerned nanomaterial could also be graphically determined as the attachment efficiency (£\) of nanoparticles increased with increasing ionic strength of the solution and then leveled off after reaching CAC. Experimental results also showed that Zn(OH)2(s) would form when nano-ZnO was in the solution of pH 10. The crystalline structure of the said precipitates was confirmed by X-ray diffraction. Likewise, Ce4+ dissolved from nano-CeO2 reacted with SO42- in aqueous solution yielding Ce(SO4)2(s). Clearly, transformation of nanomaterials might take place when they are in contact with various species in different aquatic environments. Humic acid in aqueous solution was found to be beneficial to the stability of nanomaterial of concern. Efforts have also been made to study the reaction behaviors among di(2-ethylhexyl)phthalate, erythromycin, and selected nanomaterials when they co-existed in the same solution. Their interactions, however, seemed to be unobvious. In this work it was found that under sunlight irradiation nano-ZnO did show its antibiotic effect due to photocatalysis. Nano-Ag was proven to have a strong antibacterial ability even in natural aquatic environments. It yielded the total bacteria survival ratio of less than 2% within one hour of reaction. In summary, the findings of this study showed that the behaviors of nano-ZnO, nano-Ag, and nano-CeO2 in aqueous solutions could be greatly influenced by different factors in different reaction systems.

Dans le cadre général des études de matériaux multifonctionnels, électrolytiques et catalytiques, susceptibles d'être utilisés au sein de dispositifs de détection de gaz, un système d'oxydes (1-x)CeO2. x/2Bi2O3 avec 0≤x≤1 a été élaboré par coprécipitation puis traitement thermique à 600°C. Le système ainsi obtenu correspondrait à un diagramme de phases original, constitué d'un domaine de solutions solides (Ce1-xBixO2-z pour x ≤ 0,20), d'un domaine multiphasé pour 0,3≤x≤0,7 comportant une phase de type quadratique b'-Bi2O3 et une phase cubique substituée limite (x=0,20), d'un autre domaine multiphasé pour les compositions 0,8≤x≤1, comportant une phase quadratique b-Bi2O3 et une phase monoclinique. Ces deux phases ont déjà été considérées dans la littérature comme phases métastables résultant de divers modes de refroidissement de la phase pure Bi2O3. Dans le cas présent, la stabilisation de ces deux phases b' et b en présence d'une phase substituée cubique Ce1-xBixO2-z pourrait être due à la présence d'ions cérium au sein duréseau cristallin de Bi2O3. Les interactions catalytiques entre des échantillons polycristallins de ce système avec x variable et des mélanges air-CO et air CH4 ont été étudiées par spectroscopie infrarouge à transformée de Fourier dans le domaine 100 à 525°C. Il apparait que les composés riches en cérium ou riches en bismuth n'ont pas la même réactivité vis-à-vis des gaz CH4 ou CO. Cette diversité de propriétés catalytiques pourrait être utilisée au sein de systèmes multicapteurs de gaz.Une étude de la conduction électrique du système pour x variable a été effectuée par spectroscopie d'impédance électrique entre 100 et 750°C. Les représentations Nyquist des impédances électriques ont été interprétées en mettant en jeu des modèles de type élément de phase constante ou de type Warburg pour prendre en compte l'hétérogénéité des échantillons ainsi que les phénomènes de réaction-diffusion aux électrodes. La conductivité en volume (coeur de grains) augmente avec la composition, avec deux types d'évolutions distinctes : une évolution caractéristique de la phase substituée liée à l'augmentation du taux de lacunes, une évolution dans le système biphasé avec une forte augmentation de conductivité au-dessus de x=0,3 et un maximum atteint pour x=0,7. La phase quadratique de type b'-Bi2O3 connue comme phase métastable est ainsi stabilisée au sein de ce système mixte, au moins à 600°C: elle serait à l'origine de la forte conductivité ionique observée pour la composition proche de x = 0,7.

Submitted by Automação e Estatística (sst@bczm.ufrn.br) on 2018-07-26T16:56:03Z No. of bitstreams: 1 AdrianaPaulaBatistaDosSantos_TESE.pdf: 5927875 bytes, checksum: f7c3f81c7e7da18af342d8e88099208a (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-07-26T19:13:33Z (GMT) No. of bitstreams: 1 AdrianaPaulaBatistaDosSantos_TESE.pdf: 5927875 bytes, checksum: f7c3f81c7e7da18af342d8e88099208a (MD5) / Made available in DSpace on 2018-07-26T19:13:33Z (GMT). No. of bitstreams: 1 AdrianaPaulaBatistaDosSantos_TESE.pdf: 5927875 bytes, checksum: f7c3f81c7e7da18af342d8e88099208a (MD5) Previous issue date: 2018-02-27 / Nanotubos unidimensionais constituídos de La(OH)3 e CeO2 obtidos por síntese hidrotérmica alcalina, tem atraído muito interesse nas pesquisas recentemente, em virtude de suas características físico-químicas destacáveis e aplicações potenciais. O método hidrotérmico tem sido largamente utilizado para a obtenção desse tipo de nanoestruturas, pois é uma técnica simples, de baixo custo em que as propriedades dos produtos obtidos dependem do mecanismo de formação e das condições hidrotérmicas utilizadas. O presente trabalho teve como objetivo sintetizar nanotubos de La(OH)3 e nanotubos de CeO2 através de rota hidrotérmica, livre de templates, e avaliar a influência da variação dos parâmetros de sínteses (concentração de NaOH, temperatura e tempo de síntese) e do processo de calcinação sobre as propriedades físicas e químicas das nanoestruturas obtidas. Os resultados desta pesquisa foram divididos em 5 capítulos. O capítulo 1 apresenta a fundamentação teórica, sendo abordado assuntos relevantes sobre o tema. O capítulo 2 mostra a metodologia utilizada. O capítulo 3 apresenta um artigo cujo o título é a “influência da calcinação sobre as propriedades físico-químicas de nanotubos de La(OH)3”. Os resultados mostraram que a temperatura de calcinação influencia na organização, composição e nas propriedades texturais dos nanotubos obtidos. Um material hidratado constituído de La(OH)3 com estrutura hexagonal foi obtido após a síntese hidrotérmica e se manteve após o processo de calcinação a 750 °C. No entanto, a morfologia nanotubular foi destruída, após esse processo. A calcinação a 450 °C gerou um material de composição La2O2CO3, com uma mistura de simetrias (hexagonal e tetragonal), em que a morfologia nanotubular foi preservada. Assim, nanotubos constituídos de La(OH)3 podem ser obtidos através de síntese hidrotérmica alcalina, sem direcionadores, que pode ter sua composição e propriedades alteradas, através da temperatura de calcinação, conforme aplicação catalítica desejada. O capítulo 4 apresenta os resultados da influência da concentração alcalina e da temperatura de síntese hidrotérmica sobre as propriedades morfológicas e esstruturais dos nanotubos de La(OH)3. Nanotubos constituídos de La(OH)3 organizados em uma estrutura hexagonal foram obtidos em todas as condições de sínteses realizadas, ou seja, em concentrações de NaOH de 5, 10 e 20 mol.L-1 e temperaturas de sínteses de 100, 125 e 150 °C. As nanoestruturas se diferenciaram em suas cristalinidade, tamanhos e o mecanismo envolvido na sua formação foi proposto como sendo o de dissolução/recristalização. O capítulo 5 apresenta um artigo que mostra a influência dos parâmetros de síntese (concentração de NaOH no meio reacional, temperatura e tempo de síntese) e da temperatura de calcinação sobre as algumas propriedades morfológicas, estruturais e ópticas de nanotubos de óxido de cério. Foram obtidos nanotubos hidratados constituídos de CeO2 com estrutura fluorita cúbica em alguns casos. A morfologia, hidratação, tamanho das nanoestruturas e as vacâncias de oxigênio variaram conforme a condição de síntese utilizada, proporcionando materiais com diferentes propriedades para catálise. O mecanismo envolvido na formação das nanoestruturas de CeO2 foi proposto e discutido. Assim, tods os resultados obtidos nesta pesquisa mostram pela primeira vez o domínio sobre a formação, composição e o tamanho das morfologias nanotubulares de La(OH)3 e CeO2 obtidas pela rota hidrotérmica alcalina, livre de templates, através do controle dos parâmetros de síntese e da temperatura de calcinação. Este domínio é de fundamental importância para que se possa obter nanotubos com características adequadas para aplicações específicas em catálise, sensores, dispositivos eletrônicos como também na área biomédica. / Recently, one-dimensional nanotubes consisting of La(OH)3 and CeO2 obtained by alkaline hydrothermal synthesis have attracted much interest in researches, due to their detachable physical-chemical characteristics and potential applications. The hydrothermal method has been widely used to obtain this type of nanostructures, since it is a simple, low cost technique in which the properties of the products obtained depend on the formation mechanism and the hydrothermal conditions used. The present work aims the synthesis of La(OH)3 and CeO2 nanotubes through the template-free hydrothermal route and evaluate the influence of the synthesis parameters, (such as NaOH concentration, temperature and synthesis time) and calcination temperature on the physical and chemical properties of the obtained nanostructures. The results of this research were divided into five chapters. The Chapter 1 presents the theoretical basis, addressing relevant issues on the subject. The Chapter 2 shows the materials and methods used. The Chapter 3 presents an article whose title is the "Influence of calcination on the physical-chemical properties of nanotubes of La(OH)3". The results showed that the calcination temperature influence in the organization, composition and texture properties of the obtained nanotubes. The hydrated material consisting of La(OH)3 with hexagonal structure was obtained after the hydrothermal synthesis and was maintained after the calcination at 750 °C. However, the nanotubular morphology was collapsed after this process. The calcination at 450 °C generated the La2O2CO3 composite material with a mixture of symmetries (hexagonal and tetragonal), in which the nanotubular morphology was preserved. Thus, nanotubes consisting of La(OH)3 can be obtained by the alkaline hydrothermal synthesis without templates, which have their composition and properties altered, through of the calcination temperature, according with the desired catalytic application. The Chapter 4 presents the results of the influence of alkaline concentration and hydrothermal synthesis on the morphological and structural properties of La(OH)3 nanotubes. Nanotubes composed of La(OH)3 organized in a hexagonal structure were obtained in all the synthesis conditions performed, in NaOH concentrations of 5; 10 and 20 mol L -1 and synthesis temperatures of 100; 125 and 150 °C. The nanostructures differed in their crystallinity, sizes and the mechanism involved in their formation were proposed as being the dissolution/recrystallization. The Chapter 5 presents an article that shows the influence of the synthesis parameters (such as NaOH concentration, temperature and synthesis time, and calcination temperature) on the morphological, structural and optical properties of cerium oxide nanotubes. Hydrated nanotubes consisting of CeO2 with a cubic fluorite structure were obtained in some cases. The morphology, hydration, size of nanostructures and oxygen vacancies varied according to the synthesis condition used, providing materials with different properties for catalysis. The mechanism involved in the formation of CeO2 nanostructures was proposed and discussed. Thus, all the results obtained in this research show for the first time the domain in the formation, composition and size of the nanotubular morphologies of the La(OH)3 and CeO2 obtained by the template-free hydrothermal route, through the control of the synthesis parameters and the calcination temperature. This domain is of fundamental importance in order to obtain nanotubes with characteristics suitable for specific applications in catalysis, sensors, and electronic devices as well as in the biomedical area.

Made available in DSpace on 2016-06-02T19:55:26Z (GMT). No. of bitstreams: 1 2628.pdf: 6650095 bytes, checksum: 735ff6e6d408ce155ed63ad80d7cac36 (MD5) Previous issue date: 2008-07-02 / Financiadora de Estudos e Projetos / Cu/CeO2 catalysts doped with Au, Pd or Pt (WGSR) were prepared and applied in water gas shift reaction. The CeO2 support was prepared by four different way: urea co-precipitation-gelation (CeO2-UGC), hydrothermal method (CeO2-HT), precipitation with NH4OH (CeO2-P) and Pechini method (CeO2-Pe). The CeO2-ZrO2 oxide was prepared by Pechini (CeO2-ZrO2-Pe). The Cu deposition was performed by deposition-precipitation on CeO2- UGC, CeO2-HT and CeO2-P (3, 5 or 10wt% Cu/CeO2) and by impregnation on CeO2-Pe and CeO2-ZrO2-Pe. The Au, Pd and Pt (0,2, 0,5 or 0,8wt%) deposition was made by deposition-precipitation. The supports and supported catalysts were characterized by X ray diffraction (XRD), BET specific surface area, X ray energy dispersive spectroscopy (EDS), temperature programmed reduction (TPR), X ray photoelectron spectroscopy (XPS), electronic transmission microscopy (TEM), temperature programmed reduction with dispersive X-ray absorption spectroscopy (TPR-DXAS) and temperature programmed oxidation (TPO). The catalysts were tested in low-temperature water-gas shift reaction and the products were analyzed online by gas chromatography. The results showed that the addition of ZrO2 to CeO2 avoided the decrease of specific surface area of support. The CeO2-P support presented the higher specific surface area. The addition Au, Pd or Pt increased the activity of the catalysts with lower amount metal (< 3,0 wt%). In the catalysts with metal amount higher than 0,5 wt% only the Pd promoted catalysts showed the same or higher activity than copper catalysts. The bimetallic catalysts presented diverse behaviors. In the catalysts with Au the activity decreased with the increase of Au amount. On the other hand, the catalysts with Pd presented opposite performance, with the activity increasing when Pd amount increases. The Pt promoted catalysts do not showed activity changes with increase of Pt amount. The Pd showed the best performance among the materials tested as monometallic catalyst or as promoter in the copper catalysts. / No presente trabalho foram preparados catalisadores Cu/CeO2 dopados com Au, Pd ou Pt para aplicação na reação de deslocamento gás-água, também conhecida como reação de shift ou pela sigla em inglês WGSR (water-gas shift reaction). O suporte CeO2 foi preparado por quatro métodos diferentes: Co-precipitação com uréia (CeO2-UGC), Hidrotérmico (CeO2-HT), Precipitação com NH4OH (CeO2-P) e Pechini (CeO2-Pe), sendo que também foi preparado um suporte CeO2-ZrO2 pelo método de Pechini (CeO2-ZrO2- Pe). As sínteses dos catalisadores x% Cu/CeO2 (x = 3, 5 ou 10% de Cu) foram realizadas por deposição-precipitação para obtenção de catalisadores suportados em CeO2-UGC, CeO2-HT ou CeO2-P e por impregnação para catalisadores suportados em CeO2-Pe ou CeO2-ZrO2-Pe, já a adições dos promotores Au, Pd ou Pt, em teores de 0,2, 0,5 ou 0,8% em massa, foram realizadas por deposição-precipitação. Os suportes e os catalisadores suportados foram caracterizados por difração de raios X (DRX), medida de área superficial específica pelo método BET, espectroscopia de raios X por energia dispersiva (EDS/EDX), redução à temperatura programada (RTP), espectroscopia fotoeletrônica de raios X (XPS), microscopia eletrônica de transmissão (MET), redução a temperatura programada acompanhada por espectroscopia de absorção de raios X dispersivo (DXAS) e oxidação a temperatura programada (OTP). Os catalisadores, previamente ativados, foram testados na reação de deslocamento gás-água a baixa temperatura (entre 200-350ºC) e os produtos formados foram analisados online por cromatografia gasosa. Dos resultados obtidos observou-se que a adição de ZrO2 ao CeO2 levou à estabilização do suporte, evitando a diminuição da área superficial específica. A preparação do CeO2 por precipitação com NH4OH (CeO2-P) resultou em um material com maior área superficial específica. Verificou-se também que a adição dos promotores Au, Pd ou Pt resultou em aumento de atividade dos catalisadores com os teores de metal mais baixos (<3,0% m/m), já nas amostras com teores de metal acima de 5,0%, apenas os catalisadores promovidos com Pd apresentaram desempenho catalítico igual ou superior aos dos catalisadores de cobre. Foram observados comportamentos diferentes nos catalisadores bimetálicos em relação ao aumento do teor de promotor. Enquanto os catalisadores com Au apresentam uma diminuição da atividade com o aumento da quantidade adicionada, ocorreu o contrário com os catalisadores contendo Pd; as amostras contendo Pt mantiveram a atividade quase inalterada, em todos os teores estudados. Dentre os materiais testados, o Pd mostrou melhor desempenho, tanto como catalisador monometálico quanto como promotor dos catalisadores de cobre suportados.

Pesquisas realizadas em todo o mundo exploram a possibilidade de utilizar o hidrogênio como combustível para a geração de energia, já que ele produz a chamada \"energia limpa\". O hidrogênio pode ser obtido a partir das reações de reforma de etanol, fonte renovável, em contraste com o clássico processo de obtenção a partir de derivados de petróleo. Desta forma, há um crescente interesse em pesquisa e desenvolvimento de catalisadores eficientes para gerar hidrogênio. Assim, no presente trabalho foram estudados catalisadores de ródio contendo 0,5; 1 e 3% (m/m) suportados em CeO2, Al2O3 e 20%CeO2- Al2O3 nas reações de reforma a vapor de etanol (RVE) e reforma oxidativa de etanol (ROE) visando a geração de hidrogênio. As amostras foram preparadas pelo método de impregnação úmida e caracterizadas por difração de Raios-X (XRD), área superficial específica - método B.E.T., espectroscopia dispersiva em emissão de Raios-X (EDX), espectroscopia de fotoelétrons excitada por Raios-X (XPS), espectroscopia na região do ultra-violeta e do visível (UV-vis- NIR) e redução à temperatura programada (RTP-H2). Os ensaios catalíticos, realizados entre 400 e 600ºC, mostraram altas conversões de etanol para todos os catalisadores. As maiores produções de H2, a partir das reações de RVE e ROE, foram obtidas à 600ºC com os catalisadores Rh/CeO2 e Rh/20%CeO2-Al2O3. Foi observado que a adição de oxigênio proporcionou um aumento na produção de H2, bem como na razão CO2/CO e nas deposições de carbono. / The researches made in the world explore the possibility in the use of hydrogen like a fuel for energy generation, since it produces the called \"clean energy\". The hydrogen can be obtained through of the ethanol reforming reaction, i.e. renewable source, in contrast with the classical process for obtaining from petroleum derivates. In this way, there is a crescent interest in research and development of efficient catalysts in order to obtain hydrogen. Thus, in this work were studied the rodium catalysts with 0,5; 1 e 3% (w/w) supported on CeO2, Al2O3 e 20%CeO2-Al2O3 for the ethanol steam reforming (ESR) and oxidative reforming (EOR) reactions aiming to the hydrogen generation. The samples were prepared by wet impregnation method and characterized by X-ray diffraction (XRD), specific superficial area - BET method, energy dipersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), UV-vis spectroscopy (UVvis), and temperature-programmed reduction (TPR-H2). In according to the catalytic tests, performed between 400 and 600ºC, it was obtained higher ethanol conversion values for all catalysts. The highest H2 yield it was obtained at 600ºC, with the Rh/CeO2 e Rh/20%CeO2-Al2O3 catalysts. It was observed that the addition of oxygen caused an increase in H2 production, as well as, in the CO2/CO ratio and in the carbon deposition.