Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2017-12-12T18:27:28Z No. of bitstreams: 1 AngelinneCostaAlexandrino_TESE.pdf: 3367753 bytes, checksum: c56321a7ee935dea3023d07d501a15bd (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2017-12-13T20:12:54Z (GMT) No. of bitstreams: 1 AngelinneCostaAlexandrino_TESE.pdf: 3367753 bytes, checksum: c56321a7ee935dea3023d07d501a15bd (MD5) / Made available in DSpace on 2017-12-13T20:12:54Z (GMT). No. of bitstreams: 1 AngelinneCostaAlexandrino_TESE.pdf: 3367753 bytes, checksum: c56321a7ee935dea3023d07d501a15bd (MD5) Previous issue date: 2017-09-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / H? d?cadas que a produ??o de combust?veis alternativos visando ? substitui??o do petr?leo e de seus derivados tem despertado o interesse de muitos pesquisadores em todo o planeta. Biodiesel ? uma alternativa renov?vel, o qual pode ser produzido a partir de ?leos residuais, gorduras animais e ?leos vegetais atrav?s do processo de transesterifica??o heterog?nea utilizando ?lcoois. Nesse contexto, catalisadores heterog?neos t?m se apresentado como potencial na produ??o de biodiesel em raz?o da possibilidade do seu reuso e por ser um processo mais limpo e eficiente. No presente trabalho, carv?o ativado obtido da pir?lise do lodo de esgoto (C.A), Mo2C, Mo2C/C.A e Ni (20%)-Mo2C/C.A foram avaliados no processo de transesterifica??o met?lica do ?leo de soja refinado visando ? produ??o de biodiesel. O carv?o do lodo foi tratado com o KOH no sentido de abrir os poros e promover maior ?rea especifica de contato, seguido de ativa??o f?sica. Os catalisadores a base de molibd?nio foram sintetizados a partir da rea??o g?s-s?lido utilizando como precursor heptamolibdato de am?nio e uma mistura de CH4/H2. Todos os materiais foram caracterizados utilizando as an?lises de TG, DRX, FRX, MEV, B.E.T e granulometria a laser. O processo de transesterifica??o foi avaliado em um reator de mistura constitu?do de um sistema de aquecimento e refluxo da fase alco?lica. Em temperatura constante de 65 oC, as condi??es operacionais estudadas para a rea??o foram: a natureza e concentra??o m?ssica (1 a 5%) do catalisador em rela??o ? massa do ?leo, a raz?o molar ?leo/?lcool (1/6 a 1/18), o pH do meio reacional (2,0 a 8,5), o tempo de rea??o (3 e 5 h) e a velocidade de agita??o da fase l?quida (450 e 600 rpm). Para todas as condi??es e demais catalisadores, o biodiesel foi produzido. A convers?o m?xima do ?leo de soja encontrada foi de 27,34%, no estudo cin?tico, para o catalisador Mo2C/C.A nas condi??es operacionais de 1% de catalisador, 6 h de rea??o, raz?o molar ?leo/?lcool de 1/12 e pH = 5. Na an?lise de caracteriza??o de uma amostra de biodiesel produzido o ponto de fulgor apresentou valor de 141 ?C, o qual est? acima do m?nimo especificado pela ANP. Um modelo cin?tico pseudo homog?neo foi utilizado, para o catalisador Mo2C/C.A atrav?s do qual foi mostrado que os resultados experimentais se ajustaram satisfatoriamente a uma cin?tica de 1? ordem, cuja constante cin?tica de velocidade teve como valor 0,0009 min-1. / For decades, the production of environment-friendly fuels, as alternative power sources for oil, has gained attention and interest of researchers worldwide. Biodiesel is a renewable alternative fuel that can be obtained from residual oils, animal fat and vegetable oils through heterogeneous transesterification reaction using alcohol. In this context, heterogeneous catalyst present potential for biodiesel production as they can be regenerated and provide a cleaner and more efficient process. In this work, several molybdenum carbide catalysts were tested for the transesterification reaction of soybean oil with methanol towards producing biodiesel. These catalysts were pure Mo2C, Mo2C supported over activated carbon (A.C), pure A.C and bimetallic Ni (20%)-Mo2C/A.C being this support produced from sewage sludge pyrolysis. The pyrolysis product was treated with KOH, in order to increase its porosity and promote a larger specific surface area, and later physically activated. Gas solid reaction with CH4 and H2 atmosphere was used to produce the studied molybdenum derived catalysts, and ammonium molybdate was used as molybdenum source in all cases. All catalysts were characterized in a TG, XDR, XFR, SEM, B.E.T and laser particle size analysis basis. Their activity towards transesterification reaction was evaluated by using a mixing reactor with temperature control and alcohol reflux at 65 ?C. The parameters that were manipulated for this experimental evaluation were: type and mass concentration of the catalyst (1 to 5%), oil/alcohol ratio (1/6 to 1/18), pH (2.0 to 8.5), reaction time (3 and 5h) and liquid phase agitation speed (450 and 600 rpm). For all conditions and other catalysts, biodiesel was produced. The maximum conversion found was 27.34% for the Mo2C/A.C catalyst under the operating conditions of 1% catalyst, 6 h reaction, oil/alcohol ration of 1/12 and pH = 5. In the characterization analysis of a sample of biodiesel produced the flash point presented a value of 141 ?C, which is above the minimum specified by the ANP. A pseudo homogeneous kinetics model was used, and experimental data presented agreement with a 1st order reaction with speed rate constant of 0,0009 min-1.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-07-08T21:11:24Z No. of bitstreams: 1 EmersonAlencarDeMedeiros_DISSERT.pdf: 2911970 bytes, checksum: f1aed4ff1b910b2a9a0ab98f785583a7 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-07-12T21:29:33Z (GMT) No. of bitstreams: 1 EmersonAlencarDeMedeiros_DISSERT.pdf: 2911970 bytes, checksum: f1aed4ff1b910b2a9a0ab98f785583a7 (MD5) / Made available in DSpace on 2016-07-12T21:29:33Z (GMT). No. of bitstreams: 1 EmersonAlencarDeMedeiros_DISSERT.pdf: 2911970 bytes, checksum: f1aed4ff1b910b2a9a0ab98f785583a7 (MD5) Previous issue date: 2015-10-02 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico (CNPq) / ? preocupante o descontrole por parte das ind?strias que produzem insumos relacionados aos compostos fen?licos, promovendo a emiss?o ou descarte desse poluente no meio ambiente, trazendo danos irrevers?veis ? natureza bem como ao ser humano. Diante disso, ? imprescind?vel a realiza??o de um tratamento desses efluentes antes de serem descartados no meio ambiente, reduzindo a concentra??o do contaminante ? valores determinados pela legisla??o. Procura-se, portanto, o tratamento desses efluentes utilizando novos materiais catal?ticos que viabilizem o processo como um todo. Nesse contexto, o presente trabalho tem como objetivo o tratamento, caracteriza??o e avalia??o de novos catalisadores na rea??o de degrada??o fotocatal?tica do fenol. Os ensaios foram realizados em um reator fotocatal?tico, em condi??es constantes de temperatura (50 ?C), pot?ncia da l?mpada (400 W), volume da fase l?quida (3,4 L), concentra??o do catalisador (1 g L-1), concentra??o inicial do fenol (500 ppm) e tempo de rea??o 3 horas. Preliminarmente ? rea??o foi realizado um estudo com a vaz?o de oxig?nio (410, 515, 650 e 750 mL min-1) a fim de identificar o valor ?timo (650 ml min-1) a ser utilizado no processo de degrada??o do fenol. Os demais par?metros foram variados: pH do meio reacional (3, 5,5 e 10) e a natureza do catalisador (paligorsquita acidificada calcinada, paligorsquita impregnada com 3,8% de ferro e carv?o originado da pir?lise do lodo de esgoto dom?stico). Os materiais catal?ticos foram caracterizados por DRX, FRX, BET e distribui??o granulom?trica. No processo de degrada??o fotocatal?tica do fenol, os resultados mostraram que o pH tem influ?ncia significativa na convers?o do fenol, apresentando melhores resultados para o pH igual a 5,5. Os valores da convers?o do fenol variaram entre 58% (para a paligorsquita acidificada calcinada) e 52% para o carv?o do lodo de esgoto. As amostras l?quidas analisadas por cromatografia l?quida identificaram e quantificaram os seguintes produtos da degrada??o: hidroquinona, catecol e o ?cido mal?ico. Por fim, foi proposto um mecanismo do processo reacional, considerando que o fenol ? transformado em fase homog?nea e os demais reagem na superf?cie do catalisador. Para este ?ltimo, foi aplicado o modelo Langmuir-Hinshelwood, cujos balan?os de massas conduziram a um sistema de equa??es diferenciais que foram resolvidas utilizando o m?todo num?rico associado a uma minimiza??o da fun??o objetivo para obten??o e otimiza??o dos par?metros cin?ticos e de adsor??o. O modelo se ajustou satisfatoriamente aos resultados experimentais. A partir do mecanismo proposto e com as condi??es operat?rias utilizadas no presente trabalho, a etapa mais favorecida, independente do catalisador, foi a do grupo ?cidos (originada dos compostos quin?nicos), sendo transformado em CO2 e ?gua, cuja constante de velocidade k4 apresentou valor 0,578 mol L-1 min-1 para a paligorsquita acidificada calcinada, 0,472 mol L-1 min-1 para o Fe2O3/paligorsquita e 1,276 mol L-1 min-1 para o carv?o do lodo, sendo este ?ltimo o melhor catalisador para mineraliza??o dos ?cidos em CO2 e ?gua. Os quin?nicos foram mais fortemente adsorvidos nos s?tios dos catalisadores paligorsquita acidificada calcinada e Fe2O3/paligorsquita, cujas constantes de adsor??o foram semelhantes (~4,45 L mol-1) e superior ao carv?o do lodo (3,77 L mol-1). / The uncontrolled disposal of wastewaters containing phenolic compounds by the industry has caused irreversible damage to the environment. Because of this, it is now mandatory to develop new methods to treat these effluents before they are disposed of. One of the most promising and low cost approaches is the degradation of phenolic compounds via photocatalysis. This work, in particular, has as the main goal, the customization of a bench scale photoreactor and the preparation of catalysts via utilization of char originated from the fast pyrolysis of sewage sludge. The experiments were carried out at constant temperature (50?C) under oxygen (410, 515, 650 and 750 ml min-1). The reaction took place in the liquid phase (3.4 liters), where the catalyst concentration was 1g L-1 and the initial concentration of phenol was 500 mg L-1 and the reaction time was set to 3 hours. A 400 W lamp was adapted to the reactor. The flow of oxygen was optimized to 650 ml min-1. The pH of the liquid and the nature of the catalyst (acidified and calcined palygorskite, palygorskite impregnated with 3.8% Fe and the pyrolysis char) were investigated. The catalytic materials were characterized by XRD, XRF, and BET. In the process of photocatalytic degradation of phenol, the results showed that the pH has a significant influence on the phenol conversion, with best results for pH equal to 5.5. The phenol conversion ranged from 51.78% for the char sewage sludge to 58.02% (for palygorskite acidified calcined). Liquid samples analyzed by liquid chromatography and the following compounds were identified: hydroquinone, catechol and maleic acid. A mechanism of the reaction was proposed, whereas the phenol is transformed into the homogeneous phase and the others react on the catalyst surface. For the latter, the Langmuir-Hinshelwood model was applied, whose mass balances led to a system of differential equations and these were solved using numerical methods in order to get estimates for the kinetic and adsorption parameters. The model was adjusted satisfactorily to the experimental results. From the proposed mechanism and the operating conditions used in this study, the most favored step, regardless of the catalyst, was the acid group (originated from quinone compounds), being transformed into CO2 and water, whose rate constant k4 presented value of 0.578 mol L-1 min-1 for acidified calcined palygorskite, 0.472 mol L-1 min-1 for Fe2O3/palygorskite and 1.276 mol L-1 min-1 for the sludge to char, the latter being the best catalyst for mineralization of acid to CO2 and water. The quinones were adsorbed to the acidic sites of the calcined palygorskite and Fe2O3/palygorskite whose adsorption constants were similar (~ 4.45 L mol-1) and higher than that of the sewage sludge char (3.77 L mol-1).