Les matériaux à base de vanadium sont largement utilisés comme catalyseurs pour l'oxydation de composés organiques. Les propriétés catalytiques des catalyseurs au vanadium pour l'oxydation dépendent de l'état et de la stabilité des espèces de vanadium. Dans cette étude, nous développons des nouveaux catalyseurs hétérogènes au vanadium pour la réaction d’oxydation.Dans la première partie du travail, les matériaux mésoporeux à base de silice (MCM-41) contenant du Al (III) et du Ti (IV) sont envisagés comme supports. L'effet d'ancrage chimique de ces hétéroatomes sur les ions V (V) et leur dispersion dans la silice MCM- 41 ont été étudiés à l'aide d'une analyse quantitative des spectres UV-visible de réflectance diffuse. En complément, les matériaux ont été caractérisés par diffraction des rayons X (DRX), mesure de sorption d’azote, spectroscopie de résonance magnétique électrique (RPE) et la spectroscopie Raman. Les spectres UV-visible des échantillons hydratés et déshydratés mettent en évidence la coexistence de plusieurs espèces V (V) de différente nucléarité et différent taux d'hydratation. Le décalage vers le bleu de la bande UV des échantillons contenant comme des additifs les ions Al(III) ou Ti(IV) est cohérent avec une meilleure dispersion des ions vanadium présentant entre autres plus d’espèces mononucléaires (isolées). L'effet bénéfique du titane sur la dispersion de vanadium est compatible avec la formation directe de ponts covalents de type Ti-O-V.Dans la seconde partie, les ions V(IV) ont été déposés sur des matériaux mésoporeux à base de silice en utilisant une nouvelle stratégie dite de pochoir moléculaire ou « Molecular-Stencil Patterning ». La stratégie de pochoir moléculaire s’applique à la silice contenant des tensioactifs ioniques en utilisant ces derniers comme agent de masquage lors du greffage covalent de diverses fonctions. Cette stratégie de surface moléculaire permet de contrôler à la fois le voisinage moléculaire et la dispersion à longue distance des espèces de vanadium entre elles. La caractérisation a été effectuée en utilisant plusieurs méthodes telles l’analyse thermogravimétrique (ATG), la spectroscopie de résonance magnétique nucléaire (RMN), la spectroscopie infrarouge (IR) et la spectroscopie UV-visible. L'incorporation des ions titane (IV) joue le rôle d’ancre chimique pour les ions V(IV) comme dans le chapitre précédent. Il est montré qu’une proportion de V/Ti inférieure à un et proche de trois génère les meilleures conditions pour éviter la formation de gros agrégats d’oxyde de vanadium.Enfin, ces nouveaux matériaux au vanadium ont été testés en phase liquide pour catalyser l'oxydation partielle du cyclohexane en une huile désignée par son rapport molaire K/A de cyclohexanone (K) et de cyclohexanol (A). Ce mélange est utilisé comme telle en chimie industrielle de base, an particulier comme précurseurs de l'acide adipique et de caprolactame pour la synthèse du nylon. Les tests ont démontré que l’introduction de titane combiné à la stratégie de pochoir moléculaire a notablement amélioré les propriétés catalytiques de ce type de catalyseurs au vanadium.En conclusion, la silice MCM-41 au vanadium a été conçu par l’introduction des hétéroatomes d'ancrage et de la stratégie de pochoir moléculaire, afin d'améliorer la dispersion et la stabilité des sites actifs. Les matériaux conçus ont montré de meilleures propriétés et caractéristiques catalytiques dans divers caractérisation et la réaction d'oxydation. / Vanadium-based materials are widely used as catalysts for oxidation of organic compounds. The catalytic properties of vanadium catalysts for oxidation are related closely to the state and the stability of vanadium species. Therefore, a series of vanadium-containing MCM-41 silica were designed and developed in this study, and their catalytic application for oxidation reactions was evaluated as well.In the first part of work, the chemical anchoring effect of Al(III) or Ti(IV) heteroatoms on the dispersion of V (V) in MCM-41 type silica was investigated using a quantitative analysis of diffuse reflectance UV-visible spectra. The characteristic properties of prepared materials were determined by various characterization such as X-ray diffraction (XRD), N2 sorption measurement, Electron paramagnetic resonance (EPR) spectroscopy, UV-visible spectroscopy and Raman spectroscopy. UV-visible spectra of hydrated and dehydrated samples evidenced the coexistence of several V(V) species of different oligomerization and hydration levels. The global blue shift of the band in the presence of Al(III) or Ti(IV) additives was then assigned to a higher proportion of less clustered and isolated V(V) species. The stronger beneficial effect of Ti on the vanadium dispersion is consistent with a higher stability of the X-O-V bridges moving from X = Si to X = Al and Ti. In the second part, new mesoporous silica materials containing vanadium species were synthesized according to the molecular stencil patterning technique. Molecular stencil patterning is developed specifically for silica templated with ionic surfactants used as masking agent to sequentially immobilize via covalent bonding (grafting) different functions. This molecular surface engineering was proved to improve the vanadium species dispersion according to Thermogravimetric Analysis (TGA), Nuclear Magnetic Resonance spectroscopy (NMR), Infrared spectroscopy (IR) and UV-visible spectroscopy. The incorporation of titanium species played again the role to immobilize the vanadium species as the results in previous work. The V/Ti ratio should be less than 1 to control the formation of clusters of vanadium species.Lastly, the vanadium-containing materials were applied to the liquid phase oxidation of cyclohexane into cyclohexanol (A) and cyclohexanone (K). A mixture of these two products is often called K/A oil in the industrial chemical production. K/A oil is widely used as a raw material for adipic acid and caprolactam in the nylon industry. The catalysis results proved that the modification by adding titanium chemical anchors combined with the MSP technique improve the catalytic properties of vanadium-containing heterogeneous catalysts.In conclusion, the dispersion and stability of vanadium active sites has been improved in new syntheses of vanadium-containing MCM-41 type silica by combining both anchoring heteroatoms and molecular stencil patterning techniques. Such a novel design leads to better catalytic performance in oxidation reaction in correlation with the structural and physical characteristics of the material.

Made available in DSpace on 2014-12-17T15:42:13Z (GMT). No. of bitstreams: 1 TiagoRC_DISSERT.pdf: 2194143 bytes, checksum: 2a20949c899c91ba3e574d7f71d319d4 (MD5) Previous issue date: 2012-04-11 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Oxygen carriers are metal oxides which have the ability to oxidize and reduce easily by various cycles. Due to this property these materials are widely usedin Chemical-Looping Reforming processes to produce H2 and syngas. In this work supports based on MCM-41 and La-SiO2 were synthesized by hydrothermal method. After the synthesis step they were calcined at 550?C for 2 hours and characterized by TG, XRD, surface area using the BET method and FTIR spectroscopy. The deposition of active phase, in this case Nickel, took place in the proportions of 5, 10 and 20% by weight of metallic nickel, for use as oxygen carriers.The XRD showed that increasing in the content of Ni supported on MCM-41 resulted in a decrease in spatial structure and lattice parameter of the material. The adsorption and desorption curves of the MCM-41 samples exhibited variations with the increase of Ni deposited. Surface area, average pore diameter and wall density of silica showed significant changes , due to the increase of the active phase on the mesoporous material. By other hand, in the samples with La-SiO2 composition was not observed peaks characteristic of hexagonal structure, in the XRD diffractogram. The adsorption/desorption isotherms of nitrogen observed are type IV, characteristic of mesoporous materials. The catalytic test indicates that the supports have no influence in the process, but the nickel concentration is very important, because the results for minor concentration of nickel are not good. The ratio H2/O2 was close to 2, for all 15 cycles involving the test storage capacity of O2, indicating that the materials are effective for oxygen transport / Transportadores de oxig?nio s?o ?xidos met?licos que possuem a capacidade de oxidar e reduzir facilmente por diversos ciclos. Devido a essa propriedade estes materiais s?o bastante utilizados nos processos de Chemical-Looping Reforming para a produ??o de H2 ou g?s de s?ntese (H2 mais CO). Neste trabalho foram sintetizados os suportes MCM-41 e La-SiO2 pelo o m?todo hidrot?rmico. Os materiais resultantes foram calcinados a 550 ?C por 2 horas e, posteriormente, caracterizados por TG, DRX, ?rea superficial pelo m?todo BET e FTIR. Ap?s a caracteriza??o dos suportes foi feita a deposi??o da fase ativa (Ni) com as propor??es de 5, 10 e 20% em massa de n?quel met?lico, para aplica??o como transportadores de oxig?nio. As an?lises de DRX mostraram que o aumento do teor de Ni suportado em MCM-41 deu origem a uma diminui??o no ordenamento estrutural e no par?metro de rede do material. As amostras MCM-41 apresentaram varia??es quanto ?s curvas de adsor??o/dessor??o de nitrog?nio, ?rea superficial, di?metro m?dio de poros e espessura da parede de s?lica, em fun??o do aumento da fase ativa no material mesoporoso. Enquanto que nas amostras com La-SiO2 n?o se observou picos caracter?sticos da estrutura hexagonal, nos difratogramas de DRX. Entretanto, as curvas de adsor??o/dessor??o de nitrog?nio observadas s?o do tipo IV, caracter?stico de materiais mesoporosos. Os resultados dos testes dos transportadores indicam que o suporte n?o influenciou no processo catal?tico. A raz?o H2/O2 foi pr?xima de 2, durante todos os 15 ciclos envolvendo o teste de capacidade de armazenamento de O2 , indicando que os materiais s?o eficientes para o transporte de oxig?nio estrutural e no par?metro de rede do material. As amostras MCM-41 apresentaram varia??es quanto ?s curvas de adsor??o/dessor??o de nitrog?nio, ?rea superficial, di?metro m?dio de poros e espessura da parede de s?lica, em fun??o do aumento da fase ativa no material mesoporoso. Enquanto que nas amostras com La-SiO2 n?o se observou picos caracter?sticos da estrutura hexagonal, nos difratogramas de DRX. Entretanto, as curvas de adsor??o/dessor??o de nitrog?nio observadas s?o do tipo IV, caracter?stico de materiais mesoporosos. Os resultados dos testes dos transportadores indicam que o suporte n?o influenciou no processo catal?tico. A raz?o H2/O2 foi pr?xima de 2, durante todos os 15 ciclos envolvendo o teste de capacidade de armazenamento de O2 , indicando que os materiais s?o eficientes para o transporte de oxig?nio

Este trabajo ha sido realizado en el contexto de los proyectos de MAT 2002-03808 y MAT 2002-02158, financiados por la Dirección General de Investigación del Ministerio de Ciencia y Tecnología (MCyT). Se han sintetizado y caracterizado catalizadores Rh-soportado (sólo o promovido con Sn) utilizando diferentes tipos de soportes. Como soportes de catalizadores se utilizaron tanto materiales microporosos, silicatos laminares (bentonitas) de distinta procedencia y bentonitas modificadas mediante la introducción de pilares (PILC's) o transformadas en productos zeolíticos; como materiales mesoporosos, MCM-41, con una o dos fuentes de Silicio. Los mencionados catalizadores han sido aplicados en la hidrogenación de crotonaldehído, en fase gaseosa y condiciones suaves, de alto interés tanto académico como industrial en química fina, farmacéutica y alimentaria. Se han analizado y discutido la actividad/selectividad en relación con las diferentes características de los soportes y las distintas condiciones de trabajo como: temperatura de reducción del Rh, temperaturas de reacción, y presencia de estaño como promotor. Se han caracterizado los soportes y catalizadores mediante diferentes técnicas instrumentales UV-Vis, espectroscopia IR, ATG/DTG, DRX, isotermas de adsorción-desorción de N2, quimisorción de O2/H2, quimisorción de NH3, adsorción-desorción de piridina mediante espectroscopia IR-TF, XPS y se utilizó la Cromatografia de gases para la hidrogenación de crotonaldehído. Los resultados obtenidos ponen de manifiesto que tanto las arcillas de partida como las modificadas (con pilares o bien transformada en zeolitas) y materiales MCM-41, han resultado soportes idóneos para la formación de catalizadores heterogéneos de Rh y de Rh promovido con Sn, habiéndose generado, por tanto, nuevos materiales de alto valor añadido para el caso de las arcillas modificadas y nuevos retos de aplicación para los nuevos nanomateriales MCM-41. Así mismo se constata que la adición de Sn como promotor, modifica la conversión a todas las temperaturas de reacción, obteniéndose para todos los catalizadores, mayor selectividad hacia alcohol crotílico que en ausencia de Sn. En resumen, a lo largo de este trabajo se han logrado preparar catalizadores metal soportados utilizando unos nuevos soportes de catalizadores que muestran, generalmente, alta selectividad hacia alcohol crotílico en la hidrogenación de crotonaldehído, en condiciones suaves y a presión atmosférica, condiciones usuales de trabajo en la industria de química fina, farmacéutica y alimentaria, donde time mayor repercusión la aplicación de la reacción estudiada. / This work has been performed within the projects MAT 2002-03808 and MAT 2002-02158, financed by the DGESIC (Dirección General de Enseñanza Superior e Investigación y Ciencia) and CICYT (Comisión de Investigación Científica y Técnica), respectively.An Rh-supported catalyst (alone or promoted with Sn) has been synthesized and characterized using different types of supports. Aluminum silicate (clay) of different origins and clay modified by introduction of pillars (PILC's) or transformed into zeolytic products were used as microporous materials. MCM-41 (with one or two Silicon sources) was used as mesoporous materials. The catalyst has been applied in the hydrogenation of cortonaldehyde in gaseous phase and mild conditions. These have high academic and industrial interest. Activity and selectivity of catalysts have been analyzed at different conditions of work like: temperature of reduction of the Rh, temperatures of reaction and tin presence as promoter.These supports (micro and mesoporous materials) and catalysts have been characterized using different technical instruments: UV-Vis, spectroscopy IR, ATG/DTG, XRD, isotherms of adsorption-desorption of N2, chemisorptions of O2/H2, chemisorptions of NH3, adsorption-desorption of pyridine by DRIFTS, XPS and hydrogenation of crotonaldehyde by Gas Chromatography. The results obtained show that the natural clay material, as modified (with incorporation of pillars or transformed into zeolites), and materials MCM-41, have been good supports to the formation of heterogeneous catalysts of Rh and Rh promoted with Sn, having generated new materials of high value in the case of modified clays and raises new challenges of application for nanomaterials MCM-41. Also observed is that the addition of Sn as promoter was modifying the conversion at all temperatures of reaction, obtaining for all the catalysts greater selectivity to crotyl alcohol than without tin (Sn).In summary, throughout this work, we have been able to prepare and obtain metal supported catalysts using new supports of catalysts that show great selectivity towards crotyl alcohol in the hydrogenation of crotonaldehyde in mild conditions and atmospheric pressure. This is a very important reaction in the production of many pharmaceutical, agrochemical and fragrance compounds, having great repurcussion on the application of the studied reaction and attracting much interest in fundamental research in catalysis.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-03-19T16:45:48Z No. of bitstreams: 1 WELLINGTON SIQUEIRA LIMA - TESE PPGEQ 2015..pdf: 2629273 bytes, checksum: eb08d915f7af848456b05135a5dca125 (MD5) / Made available in DSpace on 2018-03-19T16:45:48Z (GMT). No. of bitstreams: 1 WELLINGTON SIQUEIRA LIMA - TESE PPGEQ 2015..pdf: 2629273 bytes, checksum: eb08d915f7af848456b05135a5dca125 (MD5) Previous issue date: 2015 / CNPq / Nos últimos anos, o processo de conversão de gás natural para líquidos (GTL) via síntese de Fischer-Tropsch (SFT) recebeu interesse renovado por motivos que vão desde as vastas reservas de gás natural à excelente qualidade dos combustíveis sintéticos produzidos através desse processo. Por este motivo, se faz necessário a busca por novos catalisadores que possibilitem um aumento da seletividade a produtos de maior valor agregado na reação de Fischer-Tropsch. Sendo assim, este trabalho teve como objetivos: a preparação e caracterização do suporte zeolítico MCM-22 através do método hidrotérmico estático, numa primeira etapa. A segunda parte deste trabalho consistiu na preparação dos catalisadores a base de cobalto e rutênio como promotor da reação, obtidos por impregnação úmida e suportados na zeólita MCM-22. Por fim, avaliar o desempenho dos catalisadores na reação de Fischer-Tropsch para produção de hidrocarbonetos de cadeia longa C5+. Os catalisadores foram caracterizados pelas técnicas de: Difração de Raios X, Espectroscopia Dispersiva de Raios X, Adsorção Física de N2, Redução a Temperatura Programada e Microscopia Eletrônica de Transmissão. Os testes catalíticos foram conduzidos à temperatura fixa de 240 °C, variando as pressões entre 10 e 20 bar e a alimentação H2/CO entre 1-2, em um reator leito de lama durante um período de 6 h. Os resultados mostraram ser possível obter a zeólita MCM-22 em 7, 8, 9 e 10 dias de síntese com elevada cristalinidade e áreas superficiais. Os materiais obtidos com diferentes dias de síntese serviram de suportes para os catalisadores 20%Co0,5%RuMCM-22(7D), 20%Co0,5%RuMCM22(8D) 20%Co0,5%RuMCM-22(9D) e 20%Co0,5%RuMCM-22(10D). Após aplicação na reação de Fischer-Tropsch, estes catalisadores apresentaram alta seletividades a formação de hidrocarbonetos C5+, o que sugere um alto potencial da zeólita MCM-22 como suporte catalítico desta reação. / In recent years, the natural gas conversion to liquids (GTL) via Fischer-Tropsch synthesis (FTS) has received renewed interest for reasons ranging from the vast reserves of natural gas to the excellent quality of synthetic fuels produced by this process. For this reason, if the search is necessary for new catalysts that enable an increase in selectivity to higher value-added products in the Fischer-Tropsch reaction. Thus, this study aimed to: the preparation and characterization of zeolite support MCM-22 through the static hydrothermal method, a first step. The second part of this work consisted in the preparation of the cobalt-based catalysts and ruthenium as a promoter of the reaction, obtained by wet impregnation and supported on MCM-22 zeolite. Finally, to assess the performance of catalysts in the Fischer-Tropsch reaction for the production of long chain C5+ hydrocarbons. The catalysts were characterized by techniques: X-ray diffraction, X-ray dispersive spectroscopy, N2 adsorption of Physics, Temperature Programmed Reduction and Transmission Electron Microscopy. The catalytic tests were conducted at a fixed temperature of 240 °C, pressures ranging between 10 and 20 bar and a H2/CO feed between 1-2, in a slurry bed reactor for a period of 6h. The results proved possible to obtain MCM-22 zeolite 7, 8, 9 and 10 days of synthesis with high crystallinity and surface areas. The materials obtained with different days synthesis served as supports for catalysts 20%Co0,5%RuMCM-22(7D), 20%Co0,5%RuMCM-22(8D) 20%Co0,5%RuMCM-22(9D) e 20%Co0,5%RuMCM-22(10D). After application of the Fischer-Tropsch reaction, these catalysts showed high selectivity for the formation of C5+ hydrocarbons, which suggests a high potential of MCM-22 zeolite as a catalyst support for this reaction.

Made available in DSpace on 2014-12-17T14:07:00Z (GMT). No. of bitstreams: 1 AuristelaCM_DISSERT.pdf: 1278248 bytes, checksum: cbdcf9cab5a2fc14113da4b21bc60b64 (MD5) Previous issue date: 2011-11-28 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The mesoporous molecular sieves of the MCM-41 and FeMCM-41 type are considered promissory as support for metals used as catalysts in oil-based materials refine processes and as adsorbents for environmental protection proposes. In this work MCM-41 and FeMCM41 were synthesized using rice husk ash - RHA as alternative to the conventional silica source. Hydrothermal synthesis was the method chosen to prepare the materials. Pre-defined synthesis parameters were 100?C for 168 hours, later the precursor was calcinated at 550?C for 2 hours under nitrogen and air flow. The sieves containing different proportions of iron were produced by two routes: introduction of iron salt direct synthesis; and a modification post synthesis consisting in iron salt 1 % and 5% impregnation in the material followed by thermal decomposition. The molecular sieves were characterized by X ray diffraction XRD, Fourier transform infrared spectroscopy FT-IR, X ray fluorescence spectroscopy XFR, scanning electronic microscopy SEM, specific surface area using the BET method, Termogravimetry TG. The kinetic model of Flynn Wall was used with the aim of determining the apparent activation energy of the surfactant remove (CTMABr) in the MCM- 41 porous. The analysis made possible the morphology characterization, identifying the presence of hexagonal structure typical for mesoporous materials, as well as observation of the MCM41 and iron of characteristic bands. / As peneiras moleculares mesoporosas do tipo MCM-41 e FeMCM-41, s?o consideradas promissoras como suporte para metais, usadas como catalisadores em processos de refino de materiais a base de petr?leo e como adsorventes com o prop?sito de prote??o ambiental. Neste trabalho MCM-41 e FeMCM-41 foram sintetizadas utilizando a cinza da casca de arroz CCA, como alternativa para a fonte de s?lica. O m?todo escolhido foi a s?ntese hidrotermal para o preparo dos materiais, a temperatura de 100 ?C por 168 horas em estufa, posteriormente foi calcinado a 550 ?C por 2 horas sob fluxo de nitrog?nio e ar. As peneiras moleculares contendo diferentes propor??es de ferro foram produzidas por duas rotas: introdu??o do sal de ferro no gel de s?ntese e impregna??o de 1% e 5% de ferro no MCM-41 sintetizado. As peneiras moleculares foram caracterizadas por difra??o de raios X DRX, espectroscopia no infravermelho por transformada de Fourier (Fourier transform infrared spectroscopy FT-IR), espectroscopia de fluoresc?ncia de raios X FRX, microscopia eletr?nica de varredura MEV, ?rea superficial espec?fica atrav?s do m?todo BET e Termogravimetria TG. O modelo cin?tico de Flynn Wall foi utilizado com o objetivo de determinar a energia de ativa??o aparente da remo??o do surfactante (CTMABr) nos poros do MCM-41. As an?lises possibilitaram a caracteriza??o morfol?gica, identificando a presen?a da estrutura hexagonal t?pica dos materiais mesoporosos, assim como das bandas caracter?sticas do MCM41 e do ferro.

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-08-23T19:44:24Z No. of bitstreams: 1 THIAGO RODRIGO BARBOSA BARROS – DISSERTAÇÃO (PPGEQ) 2017.pdf: 2174476 bytes, checksum: 3268fd475d20f6eff1be072f2e7fa4e3 (MD5) / Made available in DSpace on 2018-08-23T19:44:24Z (GMT). No. of bitstreams: 1 THIAGO RODRIGO BARBOSA BARROS – DISSERTAÇÃO (PPGEQ) 2017.pdf: 2174476 bytes, checksum: 3268fd475d20f6eff1be072f2e7fa4e3 (MD5) Previous issue date: 2017-02-20 / Capes / Biodiesel, que é produzido a partir de óleos vegetais ou gorduras animais através da reação de transesterificação com álcool é um excelente substituto para o diesel de petróleo por ser um combustível biodegradável derivado de fontes renováveis. A peneira molecular MCM-41 apresenta potencial para processamento de ácidos graxos visando a produção de biodiesel, por controle da composição química e por tratamentos químicos posterior a sua síntese. A inserção de óxidos metálicos pode proporcionar um aumento no desempenho catalítico da peneira molecular, possibilitando a preparação de catalisadores com maior atividade, seletividade e estabilidade térmica. O presente trabalho tem como objetivo principal a obtenção de biodiesel a partir da reação de transesterificação do óleo de soja utilizando o catalisador MoO3/25CeO2/MCM-41. Para tal afinidade, a peneira molecular foi preparada partindo-se de um gel com a seguinte composição molar da mistura reacional: 1SiO2 : 0,30 CTABr : 11 NH3 : 144 H2O. A incorporação do cério e molibdênio (em peso) no suporte MCM-41 foi por via seca. Através dos difratogramas foi possível identificar os picos característicos da peneira molecular MCM-41, como também as fases dos óxidos de cério e molibdênio na estrutura da peneira molecular, confirmando os processos de impregnação. Por meio da isoterma de adsorção de nitrogênio a peneira molecular apresentou uma área superficial SBET de 1072 m2/g e isoterma do tipo IV característica de materiais mesoporosos. O catalisador contendo 15% em peso de molibdênio e 25% em peso de cério atingiu a maior conversão em éster metílico em torno de 93% como também densidade de 0.8832 g/cm3, viscosidade cinemática 4,044 mm2/s e acidez de 0,49 mg KOH/g. / Biodiesel, which is produced from vegetable oils or animal fats by transesterification reaction with alcohol, is an excellent substitute for diesel oil being a biodegradable fuel derived from renewable. The molecular sieve MCM-41 has the potential to process fatty acids aiming biodiesel production, by controlling the chemical composition and subsequent chemical treatments to their synthesis. The inclusion of metallic oxides can provide an increase in catalytic performance of the molecular sieve, allowing th e preparation of catalysts with higher activity, selectivity and thermal stability. This study aims to obtain biodiesel from the transesterification reaction of soybean oil using the catalyst MoO3/25CeO2/MCM-41. To this affinity, the molecular sieve was prepared starting with a gel with the following molar composition of the reaction mixture: 1SiO2 : 0,30 CTABr : 11 NH3 : 144 H2O. The incorporation of cerium and molybdenum (by weight) in the MCM-41 was supported by dry. Through the XRD patterns it was possible to identify the peaks characteristic of MCM-41 molecular sieve, as well as phases of cerium and molybdenum oxides in the molecular sieve structure, confirming the impregnation process. By means of the nitrogen adsorption isotherm molecular sieve had a surface area SBET de 1072 m2/g and isotherm type IV characteristic of mesoporous materials. The catalyst containing 15% by weight molybdenum and 25% by weight cerium reached the highest methyl ester conversion around 93% as well as density of 0.8832 g/cm3, kinematic viscosity 4,044 mm2/s and acidity of 0,49 mg KOH/g

MCM-22 is a typical representative of the MWW family zeolite being obtained from laminated precursor MCM-22 (P) after calcination process having high surface area and high thermal stability. In this work, we carried out an optimization of the synthesis process of MCM-22 zeolite, in order to reduce the amount of reactants used and the crystallization time. The zeolite was synthesized using three different sources of silicon (Aerosil silica, silica gel and Ultrasil 60) and static hydrothermal treatment; in order to evaluate the influence of silicon source on the formation of the structure and physicochemical properties. The syntheses were performed without aging and with aging at room temperature and at 40 ° C for each source of silicon. It was also a study on the influence of calcination on the formation of MCM-22 structure. The materials (MCM-22 (P) and MCM-22) were characterized by X-ray diffraction (XRD); textural analysis of nitrogen adsorption at low temperature; scanning electron microscopy (SEM); spectroscopy in the infrared (FT-IR); thermogravimetry / derivative thermogravimetry (TGA / DTG) and determination of acidity termoprogramada desorption of NH3 (NH3-TPD). The X-ray diffraction showed that the synthesis of the materials has been successful, with the characteristic peaks of the MWW topology. In the conditions proposed in this work it was possible to optimize the synthesis of MCM-22 zeolite, which is obtained in a short time of 4 days without aging, for the sources of silica and Aerosil Ultrasil, and 3-day aging at 40 ° C for source of Aerosil silica. Unable to the formation of MCM-22 zeolite with silica gel within 8 days. The X-ray diffraction confirmed the obtaining of MCM-22 with high purity and crystallinity without the presence of any contaminant phase in a short time (4 days) in the absence of aging. Through the analysis (FT-IR) was confirmed the presence of the intrinsic vibrations of TO4 tetrahedrons that provide internal and external bands characteristics of these materials. Through the thermogravimetric analysis (TGA / DTG) it was found that higher weight loss occurred between 180 and 530 ° C and corresponds to the output of most of the organic driver. The results of BET showed that the textural properties of MCM-22 zeolite were heavily dependent on silicon source and treatment of synthesis gel. Generally, the samples showed a surface area higher than 500 m2 / g. From acid analysis by NH3-TPD it was observed that acid sites present in the samples were predominantly mild and strong acid sites. The source of silicon and the aging of the gel did not influence the acidity of the material. The evaluation method of calcination showed that the form of calcination used to obtain MCM-22 influences the textural properties of the zeolite. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A MCM-22 é uma zeólita típica representante da família MWW, sendo obtida a partir do precursor lamelar MCM-22(P) após processo de calcinação possuindo elevada área superficial e alta estabilidade térmica. Neste trabalho, realizou-se uma otimização do processo de síntese da zeólita MCM-22, com a finalidade de reduzir a quantidade de reagentes utilizados e o tempo de cristalização. A zeólita foi sintetizada empregando três diferentes fontes de silício (Sílica Aerosil, Ultrasil e Sílica gel 60) e tratamento hidrotérmico estático; com o objetivo de avaliar a influência da fonte de silício sobre a formação da estrutura e propriedades físico-químicas. As sínteses foram realizadas sem envelhecimento e com envelhecimento a temperatura ambiente e a 40°C, para cada fonte de silício. A influência do processo de calcinação sobre a formação da estrutura da MCM-22 também foi estudada. Os materiais obtidos (MCM-22 (P) e MCM-22) foram caracterizados por difração de raios-X (DRX); análise textural por adsorção de nitrogênio a baixa temperatura; microscopia eletrônica de varredura (MEV); espectroscopia na região do infravermelho (FT-IR); termogravimetria/termogravimetria derivada (TG/DTG), e determinação de acidez por dessorção termoprogramada de NH3 (TPD-NH3).Os difratogramas de raios-X comprovaram que a síntese dos materiais foi bem sucedida, apresentando os picos característicos da topologia MWW. Nas condições propostas neste trabalho foi possível otimizar a síntese da zeólita MCM-22, em um tempo curto de 4 dias sem envelhecimento, para as fontes de sílicas Aerosil e Ultrasil, e com 3 dias com envelhecimento a 40°C para a fonte de sílica Aerosil.Não foi possível a formação da zeólita MCM-22 com a sílica gel no período de 8 dias. Os difratogramas de raios-X comprovaram a obtenção da MCM-22 com alta pureza e cristalinidade, sem a presença de nenhuma fase contaminante, em um tempo reduzido (4 dias), e na ausência de envelhecimento. Por meio das análises (FT-IR) foi possível confirmar a presença das vibrações intrínsecas dos tetraedros TO4 que fornecem as bandas internas e externas características desses materiais. Através das análises termogravimétricas (TG/DTG) verificou-se que a maior perda de massa ocorreu entre 180 e 530 °C, e corresponde à saída da maior parte do direcionador orgânico. Os resultados de BET mostraram que as propriedades texturais da zeólita MCM-22 foram fortemente dependentes da fonte de silício e do tratamento do gel de síntese. De uma forma geral, as amostras apresentaram área superficial superior a 500 m2/g. A partir das análises de acidez por TPD-NH3 observou-se que os sítios ácidos presentes nas amostras foram, predominantemente, sítios ácidos moderados e fortes. A fonte de silício e o envelhecimento do gel não influenciaram na acidez do material. A avaliação do método de calcinação revelou que a forma de calcinação empregada para a obtenção da MCM-22 influencia nas propriedades texturais da zeólita.

Made available in DSpace on 2014-12-17T14:08:54Z (GMT). No. of bitstreams: 1 DanielleLM_DISSERT.pdf: 1223674 bytes, checksum: 2d564bea614284da929e26c705739bfb (MD5) Previous issue date: 2013-06-24 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The production of synthesis gas has received renewed attention due to demand for renewable energies to reduce the emissions of gases responsible for enhanced greenhouse effect. This work was carried out in order to synthesize, characterize and evaluate the implementation of nickel catalysts on MCM-41 in dry reforming reactions of methane. The mesoporous molecular sieves were synthesized using as silica sources the tetraethyl orthosilicate (TEOS) and residual glass powder (PV). The sieves were impregnated with 10% nickel to obtain the metallic catalysts (Ni/MCM-41). These materials were calcined and characterized by Thermogravimetric Analysis (TG), Infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Temperature-Programmed Reduction (TPR) and N2 Adsorption/Desorption isotherms (BET/BJH). The catalytic properties of the samples were evaluated in methane dry reforming with CO2 in order to produce synthesis gas to be used in the petrochemical industry. The materials characterized showed hexagonal structure characteristic of mesoporous material MCM-41 type, being maintained after impregnation with nickel. The samples presented variations in the specific surface area, average volume and diameter of pores based on the type of interaction between the nickel and the mesoporous support. The result of the the catalytic tests showed conversions about 91% CO2, 86% CH4, yelds about 85% CO and 81% H2 to Ni/MCM-41_TEOS_C, and conversions about 87% CO2, 82% CH4, yelds about 70% CO and 59% H2 to Ni/MCM-41_PV_C. The similar performance confirms that the TEOS can be replaced by a less noble materials / A produ??o de g?s de s?ntese tem recebido muita import?ncia devido a procura por fontes de energias renov?veis para reduzir as emiss?es dos gases respons?veis pelo aumento do efeito estufa. Este trabalho foi realizado com o objetivo de sintetizar, caracterizar e avaliar a aplica??o dos catalisadores de n?quel sobre MCM-41, em rea?oes de reforma a seco de metano. As peneiras moleculares mesoporosas foram sintetizadas utilizando como fontes de s?lica o Tetraetil Ortosilicato (TEOS) e o res?duo de p? de vidro (PV). As peneiras foram impregnadas com 10% de n?quel para forma??o dos catalisadores met?licos (Ni/MCM-41). Esses materiais foram calcinados e caracterizados por Termogravimetria (TG), Espectroscopia na Regi?o do Infravermelho (FTIR), Difratometria de raios X (DRX), Redu??o de Temperatura Programada (TPR) e Adsor??o e Dessor??o de N2 (BET/BJH). As propriedades catal?ticas das amostras foram avaliadas na reforma a seco de metano com CO2, tendo como objetivo a produ??o de g?s de s?ntese para utiliza??o na ind?stria petroqu?mica. Os materiais caracterizados apresentaram estrutura hexagonal caracter?stica do material mesoporoso tipo MCM-41, sendo mantida ap?s a impregna??o com n?quel. As amostras apresentaram varia??es quanto ? ?rea superficial espec?fica e volume m?dio de poros, em fun??o do tipo de intera??o existente entre o n?quel e o suporte mesoporoso. Os resultados dos testes catal?ticos mostraram convers?es de 86% de CH4 e 91% de CO2 e rendimento de 85% de CO e 81% de H2 para o material Ni/MCM-41_TEOS_C, e convers?es de 82% de CH4 e 87% de CO2 e rendimentos na produ??o do g?s de s?ntese de 70% de CO e 59% de H2 para o material Ni/MCM-41_PV. Esse comportamento semelhante comprova que o TEOS pode ser substitu?do por um material menos nobre

Pavel Jůda - Abstract The cell nucleus is a complex cellular organelle. The nucleus and nuclear processes are organized into functionally and morphologically separated nuclear subcompartments. This thesis is particularly concerned with the three following nuclear subcompartments: sites of DNA replication, Polycomb bodies and nuclear inclusions constituted of inosine monophosphate dehydrogenase 2 (IMPDH2). First, we examined the relationship between MCM proteins and DNA replication. Using immunofluorescent labeling of cells extracted prior fixation and applying cross-correlation function analysis, we showed that MCM proteins are present at the sites of active DNA synthesis. Our results contributed to the solving of the first part of so-called MCM paradox. Second, we studied the structural basis of the Polycomb bodies. Based on fluorescence microscopy studies, Polycomb bodies have been considered to be the nuclear subcompartments formed by the accumulation of Polycomb proteins in the interchromatin compartment. In our work, using correlative light electron microscopy and experimental changes in macromolecular crowding, we clearly showed that a Polycomb body is a chromosomal domain formed by an accumulation of heterochromatin structures, rather than a typical nucleoplasmic body. Third, we were interested in...

Pavel Jůda - Abstract The cell nucleus is a complex cellular organelle. The nucleus and nuclear processes are organized into functionally and morphologically separated nuclear subcompartments. This thesis is particularly concerned with the three following nuclear subcompartments: sites of DNA replication, Polycomb bodies and nuclear inclusions constituted of inosine monophosphate dehydrogenase 2 (IMPDH2). First, we examined the relationship between MCM proteins and DNA replication. Using immunofluorescent labeling of cells extracted prior fixation and applying cross-correlation function analysis, we showed that MCM proteins are present at the sites of active DNA synthesis. Our results contributed to the solving of the first part of so-called MCM paradox. Second, we studied the structural basis of the Polycomb bodies. Based on fluorescence microscopy studies, Polycomb bodies have been considered to be the nuclear subcompartments formed by the accumulation of Polycomb proteins in the interchromatin compartment. In our work, using correlative light electron microscopy and experimental changes in macromolecular crowding, we clearly showed that a Polycomb body is a chromosomal domain formed by an accumulation of heterochromatin structures, rather than a typical nucleoplasmic body. Third, we were interested in...