Made available in DSpace on 2014-12-17T14:06:59Z (GMT). No. of bitstreams: 1 LucianoLMS.pdf: 2498297 bytes, checksum: 4e0c9395aebdb6d0be7a37737a51ca92 (MD5) Previous issue date: 2008-04-29 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Oxide type spinel AB2O4 presents structure adjusted for application in the automobile industry. The spinel of cobalt has many practical applications had its excellent physical and chemical properties such as catalyst in hydrocarbon oxidation reaction. The CeO2 has been used in many of these processes because it assigns to a material with excellent thermal resistance and mechanics, high capacity of oxygen stockage (OSC) among others properties. This work deals with the synthesis, characterization and catalytic application of spinel of cobalt and CeO2 with fluorita structure, obtained for method of Pechini and method of Gel-Combustion. The process of Pechini, the puff was obtained at 300 ?C for 2 h in air. In the process of Gel-Combustion the approximately at 350 ?C material was prepared and burnt for Pyrolysis, both had been calcined at 500 ?C, 700 ?C, 900 ?C and 1050 ?C for 2 h in air. The materials of the calcinations had been characterized by TG/DTA, electronic microscopy of sweepings (MEV), spectroscopy of absorption in the infra-red ray (FTIR) and diffraction of X-rays (DRX). The obtained material reaches the phase oxide at 450 oC for Pechini method and 500 ?C for combustion method. The samples were submitted catalytic reaction of n-hexane on superficies of materials. The reactor function in molar ration of 0, 85 mol.h-1.g-1 and temperature of system was 450 ?C. The sample obtained for Pechini and support in alumine of superficial area of 178,63 m2.g-1 calcined at 700 ?C, give results of catalytic conversions of 39 % and the sample obtained for method of gel-combustion and support in alumina of 150 mesh calcined at 500 ?C result 13 % of conversion. Both method were selective specie C1 / O espin?lio de cobalto tem muitas aplica??es pr?ticas devido as suas excelentes propriedades f?sicas e qu?micas tal como catalisador nas rea??es de oxida??o de hidrocarboneto. O CeO2 tem sido utilizado em muitos processos porque designa um material com excelente resist?ncia t?rmica e mec?nica, alta capacidade de estocagem de oxig?nio (OSC) entre outras propriedades. Este trabalho trata da s?ntese e caracteriza??o e aplica??o catal?tica dos ?xidos de cobalto com estrutura espin?lio e CeO2 com estrutura fluorita, obtidos pelo m?todo de Pechini e pelo m?todo de gel-combust?o. No processo Pechini o puff foi obtido a 300 ?C por 2 h em atmosfera ambiente. No processo de gel-combust?o o material foi preparado e queimado a aproximadamente 350 ?C por igni??o espont?nea e, posteriormente, ambos os p?s foram calcinados a 500 ?C, 700 ?C, 900 ?C e 1050 ?C por 2 h em atmosfera ambiente. Os p?s-resultantes das calcina??es foram caracterizados por TG/DTA, microscopia eletr?nica de varredura (MEV), espectroscopia de absor??o no infravermelho (FTIR) e difra??o de raios X (DRX). O material obtido deve atingir a fase ?xida a 450 ?C, para Pechini e 500 ?C para gel-combust?o. As amostras foram submetidas a rea??es catal?ticas de n-hexano sobre os catalisadores de Ce/Co. O reator operou a uma raz?o F/W fluxo molar de reagente por grama de catalisador de 0,85 mol.h-1.g-1 e temperatura no leito de 450 ?C. Para amostras obtidas por Pechini calcinadas a 700 ?C e suportada em alumina com ?rea superficial de 178,63 m2.g-1 obteve-se 39 % de convers?o catal?tica. Para as amostras obtidas pelo m?todo de gel-combust?o calcinadas a 500 ?C e suportada em alumina da Porogel com 150 mesh obteve cerca de 13 % de convers?o catal?tica. Ambos os m?todos foram seletivos a esp?cie C1.

Made available in DSpace on 2014-12-17T14:07:09Z (GMT). No. of bitstreams: 1 AmandaLM_DISSERT.pdf: 3676559 bytes, checksum: 256cb3ce22bbf3b5f114a2ff3021de96 (MD5) Previous issue date: 2013-02-06 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Fuel cells are electrochemical devices that convert chemical energy into electricity. Due to the development of new materials, fuel cells are emerging as generating clean energy generator. Among the types of fuel cells, categorized according to the electrode type, the solid oxide fuel cells (SOFC) stand out due to be the only device entirely made of solid particles. Beyond that, their operation temperature is relatively high (between 500 and 1000 ?C), allowing them to operate with high efficiency. Another aspect that promotes the use of SOFC over other cells is their ability to operate with different fuels. The CeO2 based materials doped with rare earth (TR+3) may be used as alternatives to traditional NiO-YSZ anodes as they have higher ionic conductivity and smaller ohmic losses compared to YSZ, and can operate at lower temperatures (500-800?C). In the composition of the anode, the concentration of NiO, acting as a catalyst in YSZ provides high electrical conductivity and high electrochemical activity of reactions, providing internal reform in the cell. In this work compounds of NiO - Ce1-xEuxO2-δ (x = 0.1, 0.2 and 0.3) were synthesized from polymeric precursor, Pechini, method of combustion and also by microwave-assisted hydrothermal method. The materials were characterized by the techniques of TG, TPR, XRD and FEG-SEM. The refinement of data obtained by X-ray diffraction showed that all powders of NiO - Cex-1EuxO2-δ crystallized in a cubic phase with fluorite structure, and also the presence of Ni. Through the characterizations can be proved that all routes of preparation used were effective for producing ceramics with characteristics suitable for application as SOFC anodes, but the microwave-assisted hydrothermal method showed a significant reduction in the average grain size and improved control of the compositions of the phases / C?lulas a combust?vel s?o dispositivos eletroqu?micos que convertem a energia qu?mica em el?trica. Em virtude do desenvolvimento de novos materiais, as c?lulas a combust?vel v?m se destacando como promissores na gera??o de energia de forma limpa. Dentre os tipos de c?lulas a combust?vel, classificadas de acordo com o tipo de eletr?lito, destacam-se as de ?xido s?lido (SOFC), por serem as ?nicas inteiramente constitu?das por s?lidos. Al?m disso, pela sua temperatura de opera??o ser relativamente elevada (entre 500 e 1000 ?C), estas c?lulas operam com alta efici?ncia. Outro aspecto que favorece o emprego de SOFC ? a sua habilidade de operar com diferentes combust?veis, como fontes de hidrog?nio.Os materiais a base de CeO2 dopados com terras raras (TR+3) podem ser utilizados como alternativas aos tradicionais anodos de NiO-YSZ. Al?m de maior condutividade i?nica maior e menores perdas ?hmicas, elas podem operar a temperaturas mais baixas (500- 800?C). Na composi??o do anodo, a concentra??o de NiO, atuando como catalisador confere alta condutividade el?trica e alta atividade eletroqu?mica das rea??es, proporcionando a reforma interna do combust?vel na c?lula. Neste trabalho compostos de NiO - Ce1-xEuxO2-δ (x = 0,1; 0,2 e 0,3), foram sintetizados a partir do m?todo dos precursores polim?ricos, Pechini, do m?todo de combust?o e, tamb?m, pelo m?todo hidrotermal assistido por micro-ondas. Os materiais obtidos foram caracterizados atrav?s das t?cnicas de TG, DRX, TPR e MEV-FEG. O refinamento dos dados obtidos pela difra??o de raios X indicou que todos os p?s de NiO - Ce1- xEuxO2-δ cristalizaram-se em uma fase c?bica com estrutura fluorita, e tamb?m a presen?a de NiO. Todas as rotas de prepara??o utilizadas mostraram-se eficientes para a produ??o de p?s com caracter?sticas adequadas para aplica??o como anodos de SOFC, por?m o m?todo hidrotermal assistido por micro-ondas apresentou significativa redu??o do tamanho m?dio de gr?os e melhor controle das composi??es das fases

Made available in DSpace on 2014-12-17T14:09:14Z (GMT). No. of bitstreams: 1 RenataMB_TESE.pdf: 1339744 bytes, checksum: 24902b1b3636b97bbd787863d62c1f99 (MD5) Previous issue date: 2012-08-09 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The fast pyrolysis of lignocellulosic biomass is a thermochemical conversion process for production energy which have been very atratactive due to energetic use of its products: gas (CO, CO2, H2, CH4, etc.), liquid (bio-oil) and charcoal. The bio-oil is the main product of fast pyrolysis, and its final composition and characteristics is intrinsically related to quality of biomass (ash disposal, moisture, content of cellulose, hemicellulose and lignin) and efficiency removal of oxygen compounds that cause undesirable features such as increased viscosity, instability, corrosiveness and low calorific value. The oxygenates are originated in the conventional process of biomass pyrolysis, where the use of solid catalysts allows minimization of these products by improving the bio-oil quality. The present study aims to evaluate the products of catalytic pyrolysis of elephant grass (Pennisetum purpureum Schum) using solid catalysts as tungsten oxides, supported or not in mesoporous materials like MCM-41, derived silica from rice husk ash, aimed to reduce oxygenates produced in pyrolysis. The biomasss treatment by washing with heated water (CEL) or washing with acid solution (CELix) and application of tungsten catalysts on vapors from the pyrolysis process was designed to improve the pyrolysis products quality. Conventional and catalytic pyrolysis of biomass was performed in a micro-pyrolyzer, Py-5200, coupled to GC/MS. The synthesized catalysts were characterized by X ray diffraction, infrared spectroscopy, X ray fluorescence, temperature programmed reduction and thermogravimetric analysis. Kinetic studies applying the Flynn and Wall model were performed in order to evaluate the apparent activation energy of holoceluloce thermal decomposition on samples elephant grass (CE, CEL and CELix). The results show the effectiveness of the treatment process, reducing the ash content, and were also observed decrease in the apparent activation energy of these samples. The catalytic pyrolysis process converted most of the oxygenate componds in aromatics such as benzene, toluene, ethylbenzene, etc / A pir?lise r?pida da biomassa lignocelul?sica ? um processo de convers?o termoqu?mica para produ??o de energia que vem se tornando muito atratativo devido ao aproveitamento energ?tico de seus produtos: g?s (CO, CO2, H2, CH4, etc), l?quido (bio-?leo) e carv?o vegetal. O bio-?leo ? o principal produto da pir?lise r?pida, sendo a sua composi??o e caracter?sticas finais intrinsecamente relacionadas ? qualidade da biomassa (elimina??o de cinzas, teor de umidade, teor de celulose, hemicelulose e lignina) bem como ? efici?ncia da remo??o dos compostos oxigenados que causam caracter?sticas indesej?veis como aumento da viscosidade, instabilidade, corrosividade e baixo poder calor?fico. Os compostos oxigenados s?o originados no processo de pir?lise convencional da biomassa onde o uso de catalisadores s?lidos, em geral, permite a minimiza??o destes produtos melhorando a qualidade do produto final, o bio-?leo. O presente trabalho teve como objetivo avaliar os produtos da pir?lise catal?tica do capim elefante (Pennisetum purpureum Schum) utilizando catalisadores s?lidos, ?xidos a base de tungst?nio, suportados ou n?o em materiais mesoporosos do tipo MCM-41, derivados da s?lica da casca do arroz, visando ? redu??o de compostos oxigenados produzidos na pir?lise. O tratamento da biomasssa atrav?s da lavagem com ?gua aquecida (CEL) ou lavagem com solu??o ?cida (CELix), bem como a aplica??o de catalisadores a base de tungst?nio nos vapores provenientes do processo de pir?lise, teve a finalidade de melhorar a qualidade dos produtos da pir?lise. A pir?lise convencional e catal?tica da biomassa foram realizadas em um micro pirolisador, Py-5200, acoplado ao GC/MS. Os catalisadores sintetizados foram caracterizados por Difra??o de raios X, Espectroscopia na regi?o do infravermelho, Fluoresc?ncia de Raios X, Redu??o por Temperatura Programada e An?lise termogravim?trica. Estudos cin?ticos aplicando o modelo de Flynn Wall foram realizados com a finalidade de avaliar a energia de ativa??o aparente da decomposi??o t?rmica da holoceluloce nas amostras de capim elefante (CE, CEL e CELix). Os resultados mostraram a efici?ncia do processo de tratamento, reduzindo o teor de cinzas, como tamb?m foi observada a diminui??o na energia de ativa??o aparente dessas amostras. O processo de pir?lise catal?tica converteu a maioria dos produtos oxigenados do CE em arom?ticos como benzeno, tolueno, etilbenzeno, etc

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-01-04T20:50:47Z No. of bitstreams: 1 AndreLuisLopesMoriyama_TESE.pdf: 5424215 bytes, checksum: 7e441e3f7c8e167e83a6733578cbcab5 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-01-05T22:00:58Z (GMT) No. of bitstreams: 1 AndreLuisLopesMoriyama_TESE.pdf: 5424215 bytes, checksum: 7e441e3f7c8e167e83a6733578cbcab5 (MD5) / Made available in DSpace on 2016-01-05T22:00:58Z (GMT). No. of bitstreams: 1 AndreLuisLopesMoriyama_TESE.pdf: 5424215 bytes, checksum: 7e441e3f7c8e167e83a6733578cbcab5 (MD5) Previous issue date: 2014-11-06 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / Esta tese ? parte de pesquisa sobre novos materiais para catalisadores e sensores de g?s mais ativos, sens?veis, e seletivos. O objetivo desta tese foi desenvolver e caracterizar ferrita de cobalto em diferentes morfologias, a fim de estudar sua influ?ncia sobre a resposta el?trica e a atividade catal?tica do material. Foi tamb?m de hierarquizar estes nanocristalitos para obter maior difusividade do g?s no material. Os p?s foram produzidos via hidrot?rmica e solvot?rmica, e foram caracterizados por termogravimetria, difra??o de raios X, microscopia eletr?nica de varredura, microscopia eletr?nica de transmiss?o (difra??o de el?trons, simula??es de alta resolu??o), e espectroscopia de energia dispersiva. As propriedades catal?ticas e el?tricas foram testados em presen?a dos gases CO e NO2, este ?ltimo em diferentes concentra??es (1- 100 ppm), e a diferentes temperaturas (temperatura ambiente at? 350 ?C). Nanooctaedros com tamanho m?dio de 20 nm foram obtidos por via hidrot?rmica. Determinou-se que a forma dos cristalitos est? principalmente associada ? natureza do agente precipitante e ? presen?a de ?ons OHno meio de rea??o. Por via solvot?rmico, foram preparados p?s esf?ricos de CoFe2O4 e com tamanho de cristalitos de 8 e 20 nm. Os p?s de CoFe2O4 apresentam uma resposta forte a pequenas quantidades de NO2 (10 ppm a 200 ?C). Os nanooctatedros tem maior sensibilidade do que os cristalitos esf?ricos de mesmo tamanho, e apresentam menor tempo de resposta e menor tempo de retorno. Estes resultados foram confirmados atrav?s da modelagem da cin?tica de resposta e de recupera??o do sensor. Testes iniciais de atividade catal?tica na rea??o de oxida??o do CO entre 100 ? e 350 ? C mostram que o efeito do tamanho ? predominante em rela??o ao efeito da forma no que diz respeito ? convers?o da rea??o. A morfologia dos cristalitos nanom?tricos influenciou a taxa da rea??o. Uma maior taxa de rea??o ? obtida em presen?a de nanooctaedros. A fim de melhorar as propriedades de detec??o e catal?ticas do material, n?s desenvolvemos uma metodologia de hierarquiza??o de nanocristalitos que envolve o uso de templates a base de carbono. / This thesis is part of research on new materials for catalysis and gas sensors more active, sensitive, selective. The aim of this thesis was to develop and characterize cobalt ferrite in different morphologies, in order to study their influence on the electrical response and the catalytic activity, and to hierarchize these grains for greater diffusivity of gas in the material. The powders were produced via hydrothermal and solvothermal, and were characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, transmission electron microscopy (electron diffraction, highresolution simulations), and energy dispersive spectroscopy. The catalytic and electrical properties were tested in the presence of CO and NO2 gases, the latter in different concentrations (1-100 ppm) and at different temperatures (room temperature to 350 ? C). Nanooctahedra with an average size of 20 nm were obtained by hydrothermal route. It has been determined that the shape of the grains is mainly linked to the nature of the precipitating agent and the presence of OH ions in the reaction medium. By solvothermal method CoFe2O4 spherical powders were prepared with grain size of 8 and 20 nm. CoFe2O4 powders exhibit a strong response to small amounts of NO2 (10 ppm to 200 ? C). The nanooctahedra have greater sensitivity than the spherical grains of the same size, and have smaller response time and shorter recovery times. These results were confirmed by modeling the kinetics of response and recovery of the sensor. Initial tests of catalytic activity in the oxidation of CO between temperatures of 100 ?C and 350 ?C show that the size effect is predominant in relation the effect of the form with respect to the conversion of the reaction. The morphology of the grains influence the rate of reaction. A higher reaction rate is obtained in the presence of nanooctahedra. In order to improve the detection and catalytic properties of the material, we have developed a methodology for hierarchizing grains which involves the use of carbonbased templates.

Made available in DSpace on 2014-12-17T15:01:51Z (GMT). No. of bitstreams: 1 AristidesFSJ_TESE.pdf: 1616188 bytes, checksum: 162e291640cf71e1607267c17f431e17 (MD5) Previous issue date: 2010-10-15 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The wet oxidation of organic compounds with CO2 and H2O has been demonstrated to be an efficient technique for effluent treatment. This work focuses on the synthesis, characterization and catalytic performance of Fe-MnO2/CeO2, K-MnO2/CeO2/ palygorskite and Fe/ palygorskite toward the wet oxidative degradation of phenol. The experiments were conducted in a sludge bed reactor with controlled temperature, pressure and stirring speed and sampling of the liquid phase. Experiments were performed on the following operating conditions: temperature 130 ? C, pressure 20.4 atm, catalyst mass concentration of 5 g / L initial concentration of phenol and 0.5 g / L. The catalytic tests were performed in a slurry agitated reactor provided with temperature, pressure and agitation control and reactor liquid sampling. The influences of iron loaded on the support (0.3; 7 and 10%, m/m) and the initial pH of the reactant medium (3.1; 6.8; 8.7) were studied. The iron dispersion on the palygorskite, the phase purity and the elemental composition of the catalyst were evaluated by X-Ray Difraction (XRD), Scanning Electron Microscopy (SEM) and X-Ray Flourescence (XRF). The use of palygorskite as support to increase the surface area was confirmed by the B.E.T. surface results. The phenol degradation curves showed that the Fe3+ over palygorskite when compared with the other materials tested has the best performance toward the (Total Organic carbonic) TOC conversion. The decrease in alkalinity of the reaction medium also favors the conversion of TOC. The maximum conversion obtained from the TOC with the catalyst 3% Fe / palygorskite was around 95% for a reaction time of 60 minutes, while reducing the formation of acids, especially acetic acid. With products obtained from wet oxidation of phenol, hydroquinone, p-benzoquinone, catechol and oxalic acid, identified and quantified by High Performance Liquid Chromatography was possible to propose a reaction mechanism of the process where the phenol is transformed into the homogeneous and heterogeneous phase in the other by applying a kinetic model, Langmuir-Hinshelwood type, with evaluation of kinetic constants of different reactions involved. / A oxida??o ?mida de compostos org?nicos a CO2 e H2O tem demonstrado ser uma t?cnica interessante no tratamento de efluentes. Este trabalho tem como objetivo a s?ntese e caracteriza??o dos catalisadores Fe-MnO2/CeO2, K-MnO2/CeO2/paligorsquita e Fe/paligorsquita, assim como, a avalia??o na degrada??o oxidativa do fenol. Os experimentos foram realizados em um reator de leito de lama, com controle de temperatura, de press?o e de velocidade de agita??o e com coleta de amostras da fase l?quida. Os Experimentos foram executados nas seguintes condi??es operacionais: temperatura de 130 oC, press?o de 20,4 atm, concentra??o m?ssica do catalisador de 5 g/L e concentra??o inicial do fenol de 0,5 g/L. Os par?metros avaliados foram: teor de ferro impregnado (0,3; 7 e 10% em massa) e o pH do meio reacional (3,1; 6,8 e 8,7). Os resultados da caracteriza??o por DRX, MEV e FRX mostraram a dispers?o do ferro na paligorsquita, a pureza das fases e, finalmente, a composi??o dos elementos que constituem o catalisador. O uso da paligorsquita como suporte eleva a ?rea especifica superficial do catalisador que foi confirmada por an?lise BET. As curvas de degrada??o do fenol indicam que o catalisador Fe3+ suportado em paligorsquita tem um papel preponderante na convers?o de Carbono Org?nico Total (COT) quando comparado aos demais catalisadores. A diminui??o da alcalinidade do meio reacional favorece tamb?m a convers?o de COT. A convers?o m?xima de COT obtida com o catalisador 3% Fe/paligorsquita, foi em torno de 95 % para um tempo de rea??o de 60 minutos, reduzindo ao mesmo tempo a forma??o de ?cidos, em especial o ?cido ac?tico. Com os produtos obtidos da oxida??o ?mida do fenol, hidroquinona, p-benzoquinona, catecol e ?cido ox?lico, identificados e quantificados por Cromatografia L?quida de Alta Efici?ncia, foi poss?vel propor um mecanismo do processo reacional onde o fenol ? transformado em fase homog?nea e os demais em fase heterog?nea. Aplicou-se um modelo cin?tico, tipo Langmuir- Hinshelwood, com avalia??o das constantes cin?ticas das diferentes rea??es envolvidas

Made available in DSpace on 2014-12-17T15:41:47Z (GMT). No. of bitstreams: 1 KesiaKV.pdf: 2272602 bytes, checksum: 46f23a52fbc9d4e74dfd9f25d2f58e11 (MD5) Previous issue date: 2009-02-19 / In present work, mesoporous materials of the M41S family were synthesized, which were discovered in the early 90s by researchers from Mobil Oil Corporation, thus allowing new perspectives in the field of catalysis. One of the most important members of this family is the MCM-41, which has a hexagonal array of mesopores with pore diameters ranging from 2 to 10 nm and a high surface area, enabling it to become very promising for the use as a catalyst in the refining of oil in the catalytic cracking process, since the mesopores facilitate the access of large hydrocarbon molecules, thereby increasing the production of light products, that are in high demand in the market. The addition of aluminum in the structure of MCM-41 increases the acidity of the material, making it more beneficial for application in the petrochemical industry. The mesoporous materials MCM-41 and Al-MCM-41 (ratio Si / Al = 50) were synthesized through the hydrothermal method, starting with silica gel, NaOH and distilled water. CTMABr was used as template, for structural guiding. In Al-MCM-41 the same reactants were used, with the adding of pseudoboehmite (as a source of aluminum) in the synthesis gel. The syntheses were carried out over a period of four days with a daily adjustment of pH. The optimum conditions of calcination for the removal of the organic template (CTMABr) were discovered through TG / DTG and also through analysis by XRD, FTIR and Nitrogen Adsorption. It was found that both the method of hydrothermal synthesis and calcination conditions of the studies based on TG were promising for the production of mesoporous materials with a high degree of hexagonal array. The acidic properties of the materials were determined by desorption of n-butylamine via thermogravimetry. One proved that the addition of aluminum in the structure of MCM-41 promoted an increase in the acidity of the catalyst. To check the catalytic activity of these materials, a sample of Atmospheric Residue (RAT) that is derived from atmospheric distillation of oil from the Pole of Guamar?- RN was used. This sample was previously characterized by various techniques such as Thermogravimetry, FTIR and XRF, where through thermal analysis of a comparative study between the thermal degradation of the RAT, the RAT pyrolysis + MCM-41 and RAT + Al- MCM-41. It was found that the Al-MCM-41 was most satisfactory in the promotion of a catalytic effect on the pyrolysis of the RAT, as the cracking of heavy products in the waste occurred at temperatures lower than those observed for the pyrolysis with MCM-41, and thereby also decreasing the energy of activation for the process and increasing the rates of conversion of residue into lighter products / No presente trabalho, foram sintetizados materiais mesoporos da fam?lia M41S que foram descobertos no in?cio dos anos 90 por pesquisadores da Mobil Oil Corporation, possibilitando assim novas perspectivas no ramo da cat?lise. Um dos mais importantes membros desta fam?lia ? o MCM-41, que possui um arranjo hexagonal de mesoporos com di?metros de poros entre 2 a 10 nm e uma alta ?rea superficial, tornando-o bastante promissor para ser utilizado como catalisador no refino do petr?leo para o craqueamento catal?tico, j? que seus mesoporos facilitam o acesso de mol?culas grandes de hidrocarbonetos, aumentando assim a produ??o de produtos leves com uma alta demanda no mercado. A adi??o de alum?nio na estrutura do MCM-41 aumenta a acidez do material, tornando-o mais positivo para aplica??o na ind?stria petroqu?mica. Os materiais mesoporosos do tipo MCM-41 e Al-MCM- 41 (raz?o Si/Al=50) foram sintetizados atrav?s do m?todo hidrot?rmico partindo da S?lica gel, NaOH e ?gua destilada. Como direcionador estrutural foi utilizado CTMABr. Para o Al- MCM-41 utilizaram-se os mesmos reagentes acrescentando a pseudobohemita (fonte de alum?nio) no gel de s?ntese. As s?nteses foram realizadas durante um per?odo de quatro dias com corre??o di?ria de pH. As melhores condi??es de calcina??o para remo??o do direcionador org?nico (CTMABr) foram otimizadas por TG/DTG e atrav?s de an?lises por DRX, FTIR e adsor??o de nitrog?nio verificou-se que tanto o m?todo de s?ntese hidrot?rmica como as condi??es de calcina??o baseado nos estudos por TG foram promissores para produ??o de materiais mesoporosos com alto grau de ordena??o hexagonal. As propriedades ?cidas dos materiais foram determinadas pela dessor??o de n- butilamina via termogravimetria. Comprovou-se que a adi??o de alum?nio na estrutura do MCM-41 promoveu um aumento na acidez deste catalisador. Para verificar a atividade catal?tica desses materiais utilizou-se uma amostra do Res?duo Atmosf?rico (RAT) que ? proveniente da destila??o atmosf?rica do petr?leo proveniente do P?lo de Guamar?- RN previamente caracterizado por v?rias t?cnicas como: Termogravimetria, FTIR e FRX, realizando-se atrav?s da an?lise t?rmica um estudo comparativo entre a degrada??o t?rmica do RAT, pir?lise do RAT+MCM-41 e RAT+Al-MCM-41. Verificou-se que o Al-MCM-41 promoveu um efeito catal?tico mais satisfat?rio na pir?lise do RAT, j? que o craqueamento dos produtos pesados presentes no res?duo ocorreu em temperaturas inferiores ?s observadas para a pir?lise com MCM-41 e com isso diminuindo tamb?m a energia de ativa??o para o processo, bem como aumentando os valores de convers?o do res?duo em produtos leves

Made available in DSpace on 2014-12-17T15:42:27Z (GMT). No. of bitstreams: 1 KesiaKVC_TESE.pdf: 1888403 bytes, checksum: 628d99fa0e77dc19c5054fa5d201217e (MD5) Previous issue date: 2013-04-17 / In this work were synthesized and characterized the materials mesoporous SBA-15 and Al- SBA-15, Si / Al = 25, 50 and 75, discovered by researchers at the University of California- Santa Barbara, USA, with pore diameters ranging from 2 to 30 nm and wall thickness from 3.1 to 6.4 nm, making these promising materials in the field of catalysis, particularly for petroleum refining (catalytic cracking), as their mesopores facilitate access of the molecules constituting the oil to active sites, thereby increasing the production of hydrocarbons in the range of light and medium. To verify that the materials used as catalysts were successfully synthesized, they were characterized using techniques of X-ray diffraction (XRD), absorption spectroscopy in the infrared Fourier transform (FT-IR) and adsorption nitrogen (BET). Aiming to check the catalytic activity thereof, a sample of atmospheric residue oil (ATR) from the pole Guamar?-RN was performed the process by means of thermogravimetry and thermal degradation of catalytic residue. Upon the curves, it was observed a reduction in the onset temperature of the decomposition process of catalytic ATR. For the kinetic model proposed by Flynn-Wall yielded some parameters to determine the apparent activation energy of decomposition, being shown the efficiency of mesoporous materials, since there was a decrease in the activation energy for the reactions using catalysts. The ATR was also subjected to pyrolysis process using a pyrolyzer with gas chromatography coupled to a mass spectrometer. Through the chromatograms obtained, there was an increase in the yield of the compounds in the range of gasoline and diesel from the catalytic pyrolysis, with emphasis on Al-SBA-15 (Si / Al = 25), which showed a percentage higher than the other catalysts. These results are due to the fact that the synthesized materials exhibit specific properties for application in the process of pyrolysis of complex molecules and high molecular weight as constituents of the ATR / No presente trabalho foram sintetizados e caracterizados os materiais mesoporosos SBA-15 e Al-SBA-15, Si/Al= 25, 50 e 75, descobertos por pesquisadores da Universidade da Calif?rnia- Santa B?rbara- EUA, tendo di?metro de poros variando entre 2 a 30 nm e espessura das paredes de 3,1 - 6,4 nm, tornando estes materiais promissores na ?rea da cat?lise, especificamente para o refino do petr?leo (craqueamento catal?tico), j? que seus mesoporos facilitam o acesso das mol?culas constituintes do petr?leo aos s?tios ativos, aumentando assim a produ??o de produtos na faixa dos hidrocarbonetos leves e m?dios. Para verificar se os materiais utilizados como catalisadores haviam sido sintetizados com sucesso, os mesmos foram caracterizados atrav?s das t?cnicas de difra??o de raios-X (DRX), espectroscopia de absor??o na regi?o do infravermelho com transformada de Fourier (FTIR) e adsor??o de nitrog?nio (BET). Com o intuito de verificar a atividade catal?tica dos mesmos, utilizou-se uma amostra de Res?duo Atmosf?rico de petr?leo (RAT), proveniente do P?lo de Guamar?- RN, realizando-se atrav?s da termogravimetria o processo de degrada??o t?rmica e catal?tica do res?duo. Mediante as curvas obtidas, observou-se uma redu??o na temperatura de in?cio do processo de decomposi??o catal?tica do RAT. Pelo modelo cin?tico proposto por Flynn- Wall obtiveram-se alguns par?metros para determina??o da energia de ativa??o aparente das decomposi??es, ficando evidenciada a efici?ncia dos materiais mesoporosos, j? que houve uma diminui??o da energia de ativa??o para as rea??es utilizando os catalisadores. O RAT tamb?m foi submetido ao processo de pir?lise utilizando-se um pirolisador com cromatografia gasosa, acoplado a um espectr?metro de massa. Mediante os cromatogramas obtidos, observou-se um aumento no rendimento dos compostos na faixa da gasolina e diesel oriundos da pir?lise catal?tica, com ?nfase para o Al-SBA-15 (Si/Al= 25), que apresentou um percentual superior aos demais catalisadores. Esses resultados se devem ao fato dos materiais sintetizados exibirem propriedades espec?ficas, para aplica??o no processo de pir?lise de mol?culas complexas e com alto peso molecular, como os constituintes do RAT

Submitted by Jos? Henrique Henrique (jose.neves@ufvjm.edu.br) on 2017-06-02T20:34:08Z No. of bitstreams: 2 camila_diana_lima.pdf: 4383425 bytes, checksum: a00aa24c475acb8858df11e235a0c29c (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2017-06-14T19:40:25Z (GMT) No. of bitstreams: 2 camila_diana_lima.pdf: 4383425 bytes, checksum: a00aa24c475acb8858df11e235a0c29c (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-06-14T19:40:25Z (GMT). No. of bitstreams: 2 camila_diana_lima.pdf: 4383425 bytes, checksum: a00aa24c475acb8858df11e235a0c29c (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017 / O presente trabalho descreve o estudo de novas metodologias para obten??o de ?steres benz?licos e ?steres met?licos de ?cidos graxos (biodiesel) utilizando o NbCl5 s?lido e catalisadores heterog?neos ?cidos. No estudo, o NbCl5 s?lido foi utilizado como reagente, e nos outros m?todos foi empregado um catalisador de ni?bio enxertado em s?lica e um catalisador de grupos sulf?nicos imobilizado em s?lica. Nos processos heterog?neos a SiO2 (507 m2g-1, ?rea espec?fica) utilizada como suporte dos catalisadores, foi produzida a partir de areia constru??o e carbonato. O NbCl5 e os grupos ?SO3H foram imobilizados diretamente ? temperatura ambiente na SiO2, formando respectivamente o SiO2-Nb, com 412 m2g-1 de ?rea espec?fica e o SiO2-SO3H, com 115 m2g-1 de ?rea espec?fica. Nas esterifica??es utilizando NbCl5 s?lido foi determinado que para a obten??o de rendimentos razo?veis de ?steres de benz?licos (>85%) e ?steres met?licos (>70%) em rea??es a temperatura ambiente, a propor??o m?nima em moles de NbCl5:?lcool benz?lico deve ser 1,5:1,0 e para obten??o dos ?steres met?licos a propor??o de 1,5:6,0. Nas metodologias aplicando os catalisadores heterog?neos foi utilizada uma quantidade de 7% (m/m) do catalisador SiO2-SO3H para catalisar a esterifica??o de diferentes ?cidos carbox?licos com ?lcool benz?lico. E para as mesmas rea??es com o catalisador SiO2-Nb foi utilizada uma raz?o de 10% (m/m) do catalisador. Ambos os processos foram realizados sob refluxo na aus?ncia de um solvente; rendimentos muito semelhantes foram obtidos apesar do catalisador SiO2-SO3H possuir uma ?rea superficial muito menor que o catalisador SiO2-Nb. / Disserta??o (Mestrado) ? Programa de P?s-gradua??o em Biocombust?veis, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2017. / The current work describes the study of new methodologies for obtaining benzyl esters and methyl esters of fatty acids (biodiesel) using solid NbCl5 and heterogeneous acid catalysts. In this study, solid NbCl5 was used as a reagent, and in the other methods a silica grafted niobium catalyst and a sulphonic group catalyst immobilized on silica were used. In the heterogeneous processes the SiO2 (507 m2g-1, specific area) used as support of the catalysts, was produced from sand building and carbonate. The NbCl5 and the -SO3H groups were directly immobilized at room temperature in SiO2, forming respectively SiO2-Nb, with 412 m2g-1 of specific area and SiO2 -SO3H, with 115 m2g-1 of specific area. In the esterifications using solid NbCl5 it was determined that in order to obtain reasonable yields of benzyl esters (>85%) and methyl esters (>70%) in reactions at room temperature, the minimum mole ratio of NbCl5/benzyl alcohol should be 1,5:1,0 and in the obtainment of the methyl esters at a ratio of 1,5:6,0. In the methodologies applying the heterogeneous catalysts to an amount of 7% (w/w) of the catalyst SiO2 -SO3H to catalyze an esterification of different carboxylic acids with benzyl alcohol. Both processes were performed under reflux in the absence of a solvent; very similar yields were obtained although the SiO2-SO3H catalyst had a much lower surface area than the SiO2-Nb catalyst.

Made available in DSpace on 2014-12-17T15:01:22Z (GMT). No. of bitstreams: 1 KalyanneKPG_ate o resumo.pdf: 69797 bytes, checksum: 49f1d53a5fe82cc0c03f9f579c34a190 (MD5) Previous issue date: 2006-09-12 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The nanostructures materials are characterized to have particle size smaller than 100 nm and could reach 1 nm. Due to the extremely reduced dimensions of the grains, the properties of these materials are significantly modified relatively when compared with the conventional materials. In the present work was accomplished a study and characterization of the molybdenum carbide, seeking obtain it with particles size in the nanometers order and evaluate its potential as catalyst in the reaction of partial methane oxidation. The method used for obtaining the molybdenum carbide was starting from the precursor ammonium heptamolybdate of that was developed in split into two oven, in reactor of fixed bed, with at a heating rate of 5?C/min, in a flow of methane and hydrogen whose flow was of 15L/h with 5% of methane for all of the samples. The studied temperatures were 350, 500, 600, 650, 660, 675 and 700?C and were conducted for 0, 60, 120 and 180 minutes, and the percent amount and the crystallite size of the intermediate phases were determined by the Rietveld refinement method. The carbide obtained at 660?C for 3 hours of reaction showed the best results, 24 nm. Certain the best synthesis condition, a passivating study was accomplished, in these conditions, to verify the stability of the carbide when exposed to the air. The molybdenum carbide was characterized by SEM, TEM, elemental analysis, ICP-AES, TG in atmosphere of hydrogen and TPR. Through the elemental analysis and ICP-AES the presence carbon load was verified. TG in atmosphere of hydrogen proved that is necessary the passivating of the molybdenum carbide, because occur oxidation in room temperature. The catalytic test was accomplished in the plant of Fischer-Tropsch of CTGAS, that is composed of a reactor of fixed bed. Already the catalytic test showed that the carbide presents activity for partial oxidation, but the operational conditions should be adjusted to improve the conversion / Os materiais nanoestruturados s?o caracterizados por terem um tamanho de cristalito inferior a 100 nm podendo atingir 1 nm. Devido ?s dimens?es extremamente reduzidas dos cristalitos, as propriedades destes materiais s?o significativamente modificadas relativamente ?s dos materiais convencionais. No presente trabalho foi realizado um estudo de s?ntese e caracteriza??o do carbeto de molibd?nio, visando obt?-lo com tamanho de part?culas na ordem de nan?metros e avaliar seu potencial como catalisador na rea??o de oxida??o parcial do metano. O m?todo utilizado para obten??o do carbeto de molibd?nio foi a partir do precursor heptamolibdato de am?nio que foi desenvolvida em forno bipartido, em reator de leito fixo, com uma taxa de aquecimento de 5?C/min, em um fluxo de metano e hidrog?nio cuja vaz?o foi de 15L/h com 5% de metano para todos os ensaios. As temperaturas estudadas foram 350, 500, 600, 650, 660, 675 e 700?C e nos tempos de isoterma de 0, 60, 120 e 180 minutos, sendo que a determina??o das fases presentes, estrutura cristalina e tamanho de cristalitos foram obtidos por refinamento de estrutura pelo m?todo de Rietveld. O carbeto obtido a 660?C e 3 horas de rea??o foi o que apresentou menor tamanho de cristalito 24 nm. Determinada a melhor condi??o de s?ntese foi realizado um estudo de passivac?o, nestas condi??es, para verificar a estabilidade do carbeto ao ser exposto ao ar. O carbeto de molibd?nio foi caracterizado por MEV, MET, an?lise elementar, ICP-AES, TG em atmosfera de hidrog?nio e RTP. Atrav?s da an?lise elementar e ICP-AES foi verificada a presen?a de carbono livre. A TG em atmosfera de hidrog?nio comprovou que ? necess?ria a passivac?o do carbeto de molibd?nio, pois ele ? oxidado em temperatura ambiente. O teste catal?tico foi realizado na planta semipiloto de Fischer-Tropsch do CTGAS, que ? composta de um reator de leito fixo. O teste catal?tico mostrou que o carbeto apresenta atividade para oxida??o parcial, mas as condi??es operacionais devem ser ajustadas para melhorar a convers?o

Made available in DSpace on 2014-12-17T15:41:46Z (GMT). No. of bitstreams: 1 StevieHLpdf.pdf: 1475886 bytes, checksum: e83c49569bddebb612701e2de7e607bc (MD5) Previous issue date: 2009-08-31 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In last years it has talked a lot about the environment and the plastic waste produced and discarded. In last decades, the increasing development of research to obtain fuel from plastic material, by catalytic degradation, it has become a very attractive looking, as these tailings are discarded to millions worldwide. These materials take a long time to degrade themselves by ways said natural and burning it has not demonstrated a viable alternative due to the toxic products produced during combustion. Such products could bring serious consequences to public health and environment. Therefore, the technique of chemical recycling is presented as a suitable alternative, especially since could be obtain fractions of liquid fuels that can be intended to the petrochemical industry. This work aims to propose alternatives to the use of plastic waste in the production of light petrochemical. Zeolites has been widely used in the study of this process due to its peculiar structural properties and its high acidity. In this work was studied the reaction of catalytic degradation of high-density polyethylene (HDPE) in the presence HZSM-12 zeolites with different acid sites concentrations by thermogravimetry and pyrolysis coupled with GC-MS. The samples of the catalysts were mixed with HDPE in the proportion of 50% in mass and submitted to thermogravimetric analyses in several heating rates. The addition of solids with different acid sites concentrations to HDPE, produced a decrease in the temperature of degradation of the polymer proportional the acidity of the catalyst. These qualitative results were complemented by the data of activation energy obtained through the non-isothermal kinetics model proposed by Vyazovkin. The values of Ea when correlated to the data of surface acidity of the catalysts indicated that there is a exponential decrease of the energy of activation in the reaction of catalytic degradation of HDPE, in function of the concentration of acid sites of the materials. These results indicate that the acidity of the catalyst added to the system is one of the most important properties in the reaction of catalytic degradation of polyethylene / Nos ?ltimos anos tem-se falado muito sobre o meio ambiente e sobre o lixo pl?stico produzido e descartado. Nas ?ltimas d?cadas, o crescente desenvolvimento de pesquisas com o intuito de obter combust?veis a partir de material pl?stico, via degrada??o catal?tica, tem-se tornado uma busca muito atrativa, j? que esses rejeitos s?o descartados aos milh?es em todo mundo. Esses materiais levam muito tempo para se degradar por meios ditos naturais e sua incinera??o n?o tem se demonstrado uma alternativa vi?vel devido aos produtos t?xicos produzidos durante sua combust?o. Tais produtos conseq?entes poderiam trazer s?rios problemas de sa?de p?blica e ambiental. Logo, a t?cnica da reciclagem qu?mica apresenta-se como uma alternativa adequada, inclusive porque podemos obter fra??es leves do petr?leo que podem ser destinadas ao setor petroqu?mico. Este trabalho tem como objetivo propor alternativas para o aproveitamento de lixo pl?stico na produ??o de combust?veis l?quidos. Ze?litas tem sido amplamente utilizada no estudo desse processo devido ?s suas propriedades estruturais peculiares e sua alta acidez. Neste trabalho, investigou-se a rea??o de degrada??o de Polietileno de Alta Densidade (PEAD) na presen?a de HZSM-12, com diferentes concentra??es de s?tios ?cidos, atrav?s da termogravimetria e pir?lise acoplada ? cromatografia ? g?s e ao espectr?metro de massa (Py-GC-MS). As amostras de catalisadores foram misturadas com PEAD na propor??o de 50% em massa e submetidas a an?lises em diferentes taxas de aquecimento. A adi??o de catalisadores com diferentes concentra??es de s?tios ?cidos produziu uma diminui??o na temperatura de degrada??o do pol?mero proporcional ? acidez do catalisador. Estes resultados qualitativos foram complementados por dados da energia de ativa??o (Ea) obtidos atrav?s do modelo cin?tico n?o-isot?rmico proposto por Vyazovkin. Os valores das Ea quando correlacionados com os dados da acidez superficial dos catalisadores, indicaram que h? uma redu??o exponencial da Ea da rea??o catal?tica de degrada??o em fun??o da concentra??o dos s?tios ?cidos dos materiais, indicando que esta propriedade ? significativa neste tipo de rea??o