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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

Estudo de catalisadores para a produ??o de combust?veis alternativos: rea??o de Fischer-Tropsh e s?ntese de metanol via hidrogena??o de CO2

Mello, Mariele Iara Soares de 10 March 2017 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2018-03-20T16:46:40Z No. of bitstreams: 1 MarieleIaraSoaresDeMello_TESE.pdf: 16812894 bytes, checksum: 6e77a9036a1ea3feab8abf3d2004dd63 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2018-03-22T11:29:20Z (GMT) No. of bitstreams: 1 MarieleIaraSoaresDeMello_TESE.pdf: 16812894 bytes, checksum: 6e77a9036a1ea3feab8abf3d2004dd63 (MD5) / Made available in DSpace on 2018-03-22T11:29:20Z (GMT). No. of bitstreams: 1 MarieleIaraSoaresDeMello_TESE.pdf: 16812894 bytes, checksum: 6e77a9036a1ea3feab8abf3d2004dd63 (MD5) Previous issue date: 2017-03-10 / Estudos de catalisadores utilizados em rea??es para a produ??o de combust?veis alternativos, como a S?ntese de Fischer-Tropsch (SFT) e a S?ntese do Metanol via Hidrogena??o de CO2 foram realizados. O efeito da natureza qu?mica do ?xido do suporte sobre o desempenho de catalisadores de cobalto para a rea??o de Fischer-Tropsch foi investigado e uma s?rie de suportes foram sintetizados por meio de uma cobertura em monocamada da ?-Al2O3 com v?rios ?xidos representativos de uma ampla gama de car?ter ?cido-b?sico de Lewis, os quais foram caracterizados por espectroscopia de UV-Vis acoplado com adsor??o de alizarina. Foi poss?vel preparar catalisadores modelos com tamanho de part?culas de Co e porosidades semelhantes, possibilitando o estudo do efeito do suporte, sem sobreposi??o de fatores de difus?o ou tamanho de part?cula. A seletividade de hidrocarbonetos C13+ mostrou depend?ncia do tipo Volcano, com um m?ximo em um car?ter ?cido-base intermedi?rio. A localiza??o das nanopart?culas (NPs) das fases ativas no interior dos canais mesoporosos e o efeito de promo??o do ZrO2 nas propriedades e no desempenho catal?tico dos catalisadores na S?ntese de Metanol via Hidrogena??o de CO2 foi estudado. Tr?s m?todos de co-precipita??o foram empregados para estudar a inser??o das NPs no interior dos mesoporos do suporte. Os m?todos utilizados, ao contr?rio do m?todo de impregna??o a volume de poro convencional, se mostraram como uma forma simples e eficaz de localizar as nanopart?culas de Cu e dos promotores ZnO e ZrO2 nos mesoporos do suporte SBA-15, bem como um efeito positivo nos catalisadores com a incorpora??o do promotor ZrO2. De forma geral, a incorpora??o de ZrO2 mostrou-se eficaz na melhoria da dispers?o e localiza??o das nanopart?culas de Cu e, portanto, maior grau de intera??o do Cu0 com os promotores ZnO e ZrO2. Efeitos de localiza??o e de promo??o do ZrO2 contribuem para a produ??o de catalisadores mais ativos e seletivos para esta rea??o. / Several studies of catalysts used in reactions for the production of energy fuels, such as Fischer-Tropsch Synthesis (FTS) and Methanol Synthesis from CO2 were done. The chemical nature effect of the oxide support on the performance of Cobalt Fischer?Tropsch catalysts was investigated. A series of supports were synthesized via monolayer coverage of porous ?-Al2O3 with various representative oxides from a wide range of Lewis acid?base character, which were characterized by UV?VIS spectroscopy coupled to alizarin adsorption. It was possible to obtain model catalysts with Co particle size and porosity alike, allowing to study the effect of the support without overlapping diffusion factors or particle size. C13+ hydrocarbon selectivity showed volcano-type dependence, with a maximum of intermediate acid-base character. The the nanoparticles of Cu/ZnO/ZnO2 confinement and the promoter effect on the properties and ZrO2 was studied in the context of the catalysts performance in Methanol synthesis via Hydrogenation of CO2. Three co-precipitation methods were chosen to study the nanoparticles confinement in the mesopores. The methods used, unlike the conventional pore volume impregnation method, showed a simple and effective way to confine the Cu/ZnO/ZrO2 NPs in the mesopores of the supporting SBA-15, as well as a positive effect in catalytic converters with the ZrO2 promoter incorporation. In general, the ZrO2 incorporation was effective in improving the dispersion and confinement of Cu NPs and, therefore, a greater Cu0 interaction with ZnO and ZrO2 promoters. Effects of confinement and promotion contributed to the production of more active and selective catalysts for this reaction.

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