Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-03-20T15:53:53Z No. of bitstreams: 1 EduardoRigoti_TESE.pdf: 6435249 bytes, checksum: 4bbd6e85c62e18866d0a7a1578f6650b (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-03-21T16:06:38Z (GMT) No. of bitstreams: 1 EduardoRigoti_TESE.pdf: 6435249 bytes, checksum: 4bbd6e85c62e18866d0a7a1578f6650b (MD5) / Made available in DSpace on 2018-03-21T16:06:38Z (GMT). No. of bitstreams: 1 EduardoRigoti_TESE.pdf: 6435249 bytes, checksum: 4bbd6e85c62e18866d0a7a1578f6650b (MD5) Previous issue date: 2017-10-06 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / O objetivo desta tese foi desenvolver novos materiais catal?ticos ? base de molibd?nio (Mo) por meio da s?ntese de suportes mesoporosos de s?lica e de carv?o e avaliar seu desempenho na hidrodeoxigena??o de mol?culas plataforma em fase gasosa. O desempenho do catalisador, do suporte e do comportamento suporte/catalisador em diferentes condi??es reacionais foram estudadas. Os carbonos mesoporosos foram obtidos utilizando os materiais de s?lica (SBA-15 e KIT-6) como molde. A incorpora??o do ?xido de molibd?nio (MoO3) aos diferentes suportes foi realizada pelo m?todo de impregna??o ao ponto ?mido a fim de obter um teor de 4 e 2 ?tomos de Mo/nm?. As t?cnicas de caracteriza??o empregadas foram a difratometria de raios X (DRX), fisissor??o de N2 a 77 K, microscopia eletr?nica de varredura (MEV) e microscopia eletr?nica de transmiss?o (MET) que permitiram confirmar a s?ntese dos materiais de s?lica e carbono e a efetiva incorpora??o do ?xido de molibd?nio. A t?cnica de capacidade de estocagem de oxig?nio (OSC) permitiu investigar o efeito dos pr?-tratamentos t?rmicos sobre o MoO3 e, partir disso compreender a influ?ncia desses pr?-tratamentos no desemprenho catal?tico desses materiais. Al?m do MoO3 suportado, foram feitos testes catal?ticos com Mo2C carburado in situ e ex situ. Os materiais foram avaliados nas rea??es de hidrodeoxigena??o do fenol com temperatura de rea??o de 300 ?C e diferentes temperaturas de pr?-tratamento para o MoO3 suportado. Todos os catalisadores apresentaram seletividades a produtos desoxigenados superiores a 97 %. Os ?xidos suportados nas r?plicas de carv?es mesoporosos apresentaram convers?es superiores que o ?xido suportado nos materiais de s?lica. O aumento da temperatura de pr?-tratamento influenciou positivamente na convers?o a produtos desoxigenados para o ?xido suportado nos templates de s?lica e em suas r?plicas. As rea??es utilizando Mo2C apresentaram valores de convers?o superiores (27 %) aos valores observados com MoO3 (~1,3 ? 18,5 %), por?m n?o foi observado uma influ?ncia significativa dos suportes. / The aim of this thesis was to develop new catalytic materials through the synthesis of mesoporous silica and carbon supports for Mo impregnation to study its catalytic performance in hydrodeoxygenation of gas-phase platform molecules, where it was tried to determine the influence of the catalyst, support and support/catalyst behavior under different reaction conditions. Mesoporous carbons were obtained using the silica materials as a template. The impregnation of molybdenum oxide (MoO3) was carried out by the incipient wetness impregnation to obtain an amount of 4 and 2 Mo atoms/nm? in the silica and carbon supports. Characterization was performed using several techniques such as X-Ray Diffraction (XRD), N2 physisorption, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), by these techniques was possible to confirm the synthesis of the silica and carbon materials and the subsequent impregnation of the molybdenum oxide. The oxygen storage capacity (OSC) technique allowed investigating the effect of thermal pre-treatments on MoO3 and, from this, to understand the influence of these pre-treatments on the catalytic performance of these materials. In addition to the supported MoO3, catalytic tests were performed with in situ and ex situ carburized Mo2C. The materials were evaluated in the hydrodeoxygenation reactions of the phenol with reaction temperature of 300 ? C and different pretreatment temperatures for the MoO3 supported. All catalysts presented selectivities to deoxygenated products higher than 97%. The oxides supported on the mesoporous carbon replicates showed higher conversions than the oxide supported on the silica materials. The increase in pretreatment temperature positively influenced the conversion to deoxygenated products for the oxide supported on the silica templates and their replicates. Reactions using Mo2C showed higher conversion values (27%) to the values observed with MoO3 (~ 1.3 - 18.5%), but no significant influence of the media was observed.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-01-26T19:42:20Z No. of bitstreams: 1 CamilaPacellyBrandaoDeAraujo_DISSERT.pdf: 4969845 bytes, checksum: f1f2fb0b021589a796762546c844670e (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-01-29T17:12:23Z (GMT) No. of bitstreams: 1 CamilaPacellyBrandaoDeAraujo_DISSERT.pdf: 4969845 bytes, checksum: f1f2fb0b021589a796762546c844670e (MD5) / Made available in DSpace on 2016-01-29T17:12:23Z (GMT). No. of bitstreams: 1 CamilaPacellyBrandaoDeAraujo_DISSERT.pdf: 4969845 bytes, checksum: f1f2fb0b021589a796762546c844670e (MD5) Previous issue date: 2015-01-30 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico - CNPq / As emiss?es de compostos sulfurados pela ind?stria do refino de petr?leo v?m sendo sujeitas a legisla??es cada vez mais restritivas devido aos impactos ambientais e na sa?de humana. A remo??o de compostos de enxofre pode ocorrer atrav?s de rea??es de hidrotratamento (HDT) as quais s?o catalisadas por s?lidos, geralmente ?xidos ou sulfetos met?licos normalmente suportados em alumina. Para a remo??o de enxofre (HDS) catalisadores de Co(Ni)-Mo(W)/Al2O3 s?o os mais utilizados, por?m novos materiais vem sendo desenvolvidos para esse fim. Carbetos de metais refrat?rios foram identificados como potenciais candidatos para essa aplica??o, a dopagem destes pode ser uma alternativa para a cat?lise dessa rea??o. Os precursores para obten??o de Mo2C foram heptamolibdato de molibd?nio [(NH4)6[Mo7O24].4H2O] e nitrato de cobalto [Co(NO3)2.6H2O] e foram cominu?dos manualmente em propor??es estequiom?tricas anteriormente ? rea??o. Os precursores foram caracterizados por TG/DTA, MEV, FRX e DRX. Os carbetos de molibd?nio com adi??o de cobalto foram obtidos atrav?s de rea??o g?s-s?lido com atmosfera de metano (CH4) e hidrog?nio (H2) utilizando reator de leito fixo. Foi utilizada vaz?o total da mistura gasosa de 15L/h com 5% de CH4 e taxa de aquecimento de 5?C/min at? a temperatura de rea??o (700 ou 750?C). Dois percentuais de cobalto foram empregados: 2,5 e 5%. Foi notada a presen?a de fase CoMoO4 e MoO3 nos percursores calcinados, o que indica o ?ntimo contato entre os metais. Para os produtos da rea??o de carboneta??o a 700?C, independentemente do teor de cobalto adicionado, foi formado Mo2C-ortorr?mbica e MoO2- monocl?nica. A 750?C somente Mo2C foi detectada por DRX. N?o foi poss?vel a identifica??o de fase contendo Co pelos difratogramas em nenhuma das condi??es. Nessa temperatura, a an?lise de TOC indicou a completa convers?o dos ?xidos a carbeto, com forma??o de 8,9% de carbono livre para a amostra com 2,5% de Co, para a amostra com 5% a convers?o foi incompleta (86%). Os produtos de rea??o foram caracterizados por FRX, DRX, MEV, TOC, BET e granulometria a laser / Sulfur compounds emissions have been, on the late years, subject to more severe environmental laws due to its impact on the environment (causing the acid rain phenomena) and on human health. It has also been object of much attention from the refiners worldwide due to its relationship with equipment?s life, which is decreased by corrosion, and also with products? quality, as the later may have its color, smell and stability altered by the presence of such compounds. Sulfur removal can be carried out by hydrotreating (HDT) which is a catalytic process. Catalysts for HDS are traditionally based on Co(Ni)-Mo(W)/Al2O3. However, in face of the increased contaminants? content on crude oil, and stricter legislation on emissions, the development of new, more active and efficient catalysts is pressing. Carbides of refractory material have been identified as potential materials for this use. The addition of a second metal to carbides may enhance catalytic activities by increasing the density of active sites. In the present thesis Mo2C with Co addition was produced in a fixed bed reactor via gas-solid reaction of CH4 (5%) and H2(95%) with a precursor made of a mix of ammonium heptamolybdate [(NH4)6[Mo7O24].4H2O] and cobalt nitrate[Co(NO3)2.6H2O] at stoichiometric amounts. Precursors? where analyzed by XRF, XRD, SEM and TG/DTA. Carboreduction reactions were carried out at 700 and 750?C with two cobalt compositions (2,5 and 5%). Reaction?s products were characterized by XRF, XRD, SEM, TOC, BET and laser granulometry. It was possible to obtain Mo2C with 2,5 and 5% cobalt addition as a single phase at 750?C with nanoscale crystallite sizes. At 700?C, however, both MoO2 and Mo2C phases were found by XRD. No Co containing phases were found by XRD. XRF, however, confirmed the intended Co content added. SEM images confirmed XRD data. The increase on Co content promoted a more severe agglomeration of the produced powder. The same effect was noted when the reaction temperature was increased. The powder synthesized at 750?C with 2,5% Co addition TOC analysis indicated the complete conversion from oxide material to carbide, with a 8,9% free carbon production. The powder produced at this temperature with 5% Co addition was only partially converted (86%)

Made available in DSpace on 2016-04-28T14:58:36Z (GMT). No. of bitstreams: 1 2005 - Jose Milton Alves.pdf: 656917 bytes, checksum: a6be51ffb2d9849d6fe513c9574db587 (MD5) Previous issue date: 2005-01-27 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Two experiments were carried out at field conditions in the Department de Fitotecnia UFRRJ with the aims of the study the effect of molybdenum in cowpea (Vigna unguiculata (L.) Walp.). The seeds from the cultivar CNCx 409-11F-P2 were used with a plant population of 200.000 plants.ha-1. The first experiment was arranged in a factorial block design with 4 replications, 5 levels of Mo (100, 200, 400, 800 g.ha-1) applied in the leaves and the control, 3 times of application (32 days after germination, flowering period and seed pod filling). During the plant development, 3 harvests were made: 48 and 79 DAG and at the end of plant grown. The parameters analyzed were: number and weight of nodules, shoot and root dry weight and productivity. At the second experiment, the treatments were applied: two levels of pH (5.5 and 6.5); six levels of Mo (20, 40, 80, 160, 1280 g. ha-1) applied in the leaves and the control; 2 ways of Mo application (in the soil and foliar application); with 4 replications. The harvests were made at 62, 73 and 87 DAG and at the end of plant growth. The parameters analyzed were: number and weight of nodules, shoot and root dry weight, productivity and Mo concentration in the seeds. The foliar applications of Mo increase the number of nodules. Occurred a significant variation of weight of nodules shoot and root dry weight in function of the form of Mo application, soil or leaves. The range of Mo concentration in the seeds was between 0,45 and 26,93 g.Mo.semente-1. / Este trabalho foi desenvolvido na ?rea experimental do Departamento de Fitotecnia da UFRRJ com o objetivo de estudar a aplica??o de molibd?nio em plantas de caupi (Vigna unguiculata (L.) Walp). Foram conduzidos dois experimentos utilizando sementes da linhagem CNCx 409-11F-P2 obtendo-se uma popula??o final de 200 mil plantas.ha-1. O primeiro experimento foi conduzido em um esquema fatorial em delineamento em blocos ao acaso com 4 repeti??es, 5 n?veis de Mo aplicados via foliar (100, 200, 400, 800 g.ha-1) e testemunha, 3 ?pocas de aplica??o (32 Dias Ap?s a Germina??o, Flora??o Plena e Enchimento dos Gr?os), num total de 60 parcelas. Durante o per?odo de desenvolvimento da cultura foram realizadas coletas das plantas com 48 e 79 DAG e no final do ciclo da cultura, para determina??o do n?mero de n?dulos, do peso de n?dulos secos, do peso da parte a?rea e da raiz secas e produtividade. No segundo experimento foram utilizados 2 n?veis de pH (5,5 e 6,5), 6 n?veis de Mo via foliar (20, 40, 80, 160, 1280 g.ha-1) e testemunha, 2 formas de aplica??o do molibd?nio (sulco e foliar) que ocorreu com 56 DAG e 4 repeti??es, num total de 96 parcelas. Foram realizadas coletas das plantas com: 62, 73 e 87 DAG e no final do desenvolvimento da cultura, onde foram determinados o n?mero de n?dulos, peso de n?dulos secos, do peso da parte a?rea e da raiz secas, produtividade e concentra??o de molibd?nio nas sementes. A aplica??o foliar de Mo aumentou o n?mero de n?dulos das plantas de caupi. Ocorreu uma grande varia??o das caracter?sticas avaliadas, peso de n?dulo, raiz e parte a?rea secas em fun??o da forma de aplica??o de Mo e do pH do solo. O aumento da concentra??o de molibd?nio nas sementes foi linear, independente da forma de aplica??o e do pH. As concentra??es de Mo encontradas nas sementes ficaram entre 0,45 a 26,93 g.Mo.semente-1.

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.

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