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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Catalisadores bifuncionais ? base de silicoaluminofosfato e fosfatos de ni?bio para emprego em rea??es de hidroisomeriza??o e hidrocraqueamento do n-hexadecano

Bassan, ?ria Almeida Leal 20 November 2015 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-08-09T22:44:46Z No. of bitstreams: 1 IriaAlmeidaLealBassan_TESE.pdf: 3143028 bytes, checksum: 970a070c1dc06ffd41a2333aff70d989 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-08-10T22:36:43Z (GMT) No. of bitstreams: 1 IriaAlmeidaLealBassan_TESE.pdf: 3143028 bytes, checksum: 970a070c1dc06ffd41a2333aff70d989 (MD5) / Made available in DSpace on 2016-08-10T22:36:43Z (GMT). No. of bitstreams: 1 IriaAlmeidaLealBassan_TESE.pdf: 3143028 bytes, checksum: 970a070c1dc06ffd41a2333aff70d989 (MD5) Previous issue date: 2015-11-20 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Os lubrificantes e cortes de destilados m?dios possuem, normalmente, grandes quantidades de n-parafinas que lhes confere valores de pontos de congelamento e de fluidez mais elevados. Nesse sentido, a remo??o de n-parafinas de cadeias longas de ?leos lubrificantes e do diesel ? essencial para se obter um produto com boas propriedades de fluxo a frio. O desenvolvimento de novos catalisadores que apresentem estabilidade t?rmica e atividade catal?tica frente ? rea??o de hidroisomeriza??o ainda ? um desafio. Sendo assim, silicoaluminofosfatos (SAPO) foram sintetizados por diferentes rotas. Utilizou-se, tamb?m, tratamento p?s-s?ntese para obten??o de estruturas h?bridas e realizou-se s?nteses com direcionadores (soft templates e hard templates) de estrutura mesoporosa. Os catalisadores foram impregnados com platina, pelo m?todo de impregna??o ?mida, para posterior avalia??o catal?tica frente ? rea??o de hidroisomeriza??o do n-hexadecano. Al?m dos SAPO, fosfatos de ni?bio (NbP) tamb?m foram impregnados com platina e avaliados na referida rea??o. Ap?s a impregna??o, esses catalisadores foram caracterizados por difra??o de Raios X (DRX), adsor??o de nitrog?nio, espectroscopia no infravermelho com piridina adsorvida (IV-PY), microscopia eletr?nica de varredura (MEV), microscopia eletr?nica de transmiss?o (MET) e resson?ncia magn?tica nuclear do 29Si (29Si-RMN). Os resultados de caracteriza??o por DRX mostraram que foi poss?vel a obten??o de SAPO mesoestruturados. No entanto, para as s?nteses com soft template houve colapso da estrutura ap?s a remo??o dos direcionadores org?nicos. Mesmo assim, esses catalisadores apresentaram atividade catal?tica. Foi poss?vel a obten??o de materiais h?bridos por meio das s?nteses do SAPO-11 realizadas com hard templates e tamb?m por meio de tratamentos p?s- s?ntese em amostras de SAPO-11. Ademais, os NbP apresentaram DRX caracter?sticos de materiais amorfos, com alta acidez e foram ativos na convers?o do n-hexadecano. / Lubricants and cutting middle distillates typically have large amounts of n-paraffins to increase its freezing point and fluidity. Accordingly, the removal of n-paraffins of long chain lubricants oils and diesel is essential to get a product with good cold flow properties. The development of new catalysts, which exhibit thermal stability and catalytic activity for the hydroisomerization reaction is still a challenge. Thus, silicoaluminophosphates (SAPO) were synthesized by different routes. Have been used also post-synthesis treatment for obtaining hybrid structures and others synthesis have been carried out with mesoporous template (soft and hard-template). Therefore, SAPO have been impregnated with H2PtCl6 solution by the incipient wetness method. Then assessments of catalytic activities in hydroisomerization and hydrocracking reactions of hexadecane have been held. Besides SAPO, niobium phosphate - NbP - were also impregnated with platinum and evaluated in the same reaction. After impregnation, these catalysts have been characterized by X-ray diffraction (XRD), nitrogen adsorption, infrared spectroscopy with adsorbed pyridine (IV-PY), scanning electron microscopy (SEM) and resonance nuclear magnetic 29Si (29Si-NMR). The characterization results by XRD have shown that it has been possible to obtain mesoporous SAPOs. However, for the syntheses with soft template there was collapse of the structure after removal of the organic template. Even so, these catalysts have been actives. It was possible to obtain hybrid materials through the synthesis of SAPO-11 made with hard templates and by means of post-synthesis treatments samples of SAPO-11. Moreover, NbP has shown characteristic XRD of amorphous materials, with high acidity and were active in the conversion of hexadecane.
2

Síntese e avaliação de NiMo/Beta e NiMo/SAPO-5 no hidrocraqueamento do cumeno com piridina.

CABRAL, Rucilana Patrícia Bezerra. 12 September 2018 (has links)
Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-09-12T14:38:14Z No. of bitstreams: 1 RUCILANA PATRÍCIA BEZERRA CABRAL - TESE (PPGEP) 2008.pdf: 6571244 bytes, checksum: d2b524bd924cc294214a4507138e3b56 (MD5) / Made available in DSpace on 2018-09-12T14:38:14Z (GMT). No. of bitstreams: 1 RUCILANA PATRÍCIA BEZERRA CABRAL - TESE (PPGEP) 2008.pdf: 6571244 bytes, checksum: d2b524bd924cc294214a4507138e3b56 (MD5) Previous issue date: 2008-07-06 / Devido ao aumento na produção de óleo pesado, a indústria do refino voltou-se para os processos de hidrocraqueamento (HCC) que fornecem combustíveis básicos e leves atendendo as exigências da sociedade moderna. O processo HCC é realizado, geralmente, sob temperaturas e pressões elevadas na presença do hidrogênio e de um catalisador de hidrocraqueamento. As cargas de petróleo brasileiras inevitavelmente contêm muitas impurezas, como os compostos orgânicos nitrogenados. Estes compostos de nitrogênio presentes nas cargas de hidrocraqueamento atuam como venenos temporários dos catalisadores, resultando numa diminuição de atividade destes catalisadores. Normalmente, os catalisadores de HCC compreendem de um suporte ácido mais um componente hidrogenante selecionado do Grupo VIB e do grupo VIII da Tabela periódica dos Elementos, na forma de óxido ou sulfeto. Zeólita Beta e SAPO-5 foram propostos para serem usados como suportes ácidos. A respeito do componente hidrogenante, a combinação de metais usados, expressada como óxidos, foi NiO-MoO3. Uma série de catalisadores NiMo suportados em Zeólita Beta e SAPO-5, de diferentes composições, foram preparados por impregnação seqüencial úmida dos materiais utilizando soluções aquosas precursoras de Ni(NO3)2.6H2O e (NH4)6 Mo7O24. 4H2O. Os suportes e catalisadores foram analisados pelas técnicas: Difração de raios-X (DRX), Espectrometria de Emissão Atômica de Plasma Acoplado Induzido (ICPAES), Adsorção Física de N2 pelo método BET, Redução com Temperatura Programada (RTP), Microscopia Eletrônica de Transmissão (MET), Espectroscopia no Infravermelho de piridina adsorvida (IV), Espectroscopia de Refletância Difusa (DRS) e Espectroscopia de Ressonância Magnética Nuclear (RMN). Os catalisadores NiMo sulfetados foram avaliados usando um reator tubular de fluxo contínuo, no hidrocraqueamento do cumeno na presença e ausência de piridina. Foi verificado que os catalisadores suportados em zeólita Beta promoveram maiores conversões que os suportados em SAPO-5, principalmente o que usou zeólita Beta (Si/Al=8,2) com 4%NiO e 15%MoO3. A presença da piridina foi prejudicial à performance de todos os catalisadores, inclusive para os padrões cedidos pelo CENPES. / Due to the increasing of the heavier crude oil feedstocks production, the oil refining industry has turned to hydrocracking (HCK) processes to provide the lighter basic fuels which modern society demands. The HCK process is generally carried out under high temperatures and pressures in the presence of the hydrogen and a HCK catalyst. The feedstocks of the Brazilian crudes inevitably contain many impurities, such as organic nitrogen compounds. These nitrogen compounds present in the feeds of hydrocracking process act as, temporary poisons to the catalysts, thereby decreasing the catalyst activity. Usually, hydrocracking catalysts comprise of an acidic support plus a hydrogenating component selected from the Group VIB metals and Group VIII metals of the Periodic Table of the Elements, in their oxide or sulfide form. Beta zeolite and SAPO-5 are proposed as acidic support materials for hydrocracking. Regarding the hydrogenation component the combination of the metals used in the form of oxides, was NiO-MoO3. A series of NiMo catalysts supported on Beta zeolite and SAPO-5, of different compositions, were prepared by sequential incipient wetness impregnation of the materials with aqueous solutions of Ni(NO3)2 . 6H2O and (NH4)6 Mo7O24.4H2O. The supports and catalysts were analyzed by several techniques such as: X-ray diffraction (XRD), plasma-emission spectrometry (ICP-AES), N2 physical adsorption by BET method, temperature programmed reduction (TPR), transmission electronic microscopy (TEM), infrared spectroscopy of adsorbed pyridine (IR), diffuse reflectance spectroscopy (DRS) and nuclear magnetic resonance (NMR) spectroscopy. The sulfide NiMo catalysts were evaluated using a continuous-flow tubular reactor by the cumene hydrocracking in the presence and absence of pyridine. It was verified that the NiMo catalysts based on Beta zeolite produced the highest cumene conversion than those based on SAPO-5, particularly the one with Beta zeolite (Si/Al=8,2) containing 4%NiO and 15%MoO3. The presence of nitrogen as pyridine was detrimental for the performance of all catalysts, including the standards one, supplied for the CENPES.

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