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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

Efeito da adiÃÃo de palÃdio sobre as propriedades fotocatalÃticas do Ãxido de titÃnio suportado em Ãxido de alumÃnio / Effect of palladium on the photocatalytic properties of titanium oxide supported on aluminum oxide

Raquel Abreu da Silva 29 June 2015 (has links)
CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / Visando a aplicaÃÃo fotocatalÃtica na decomposiÃÃo de substratos quÃmicos, o mÃtodo de rÃplica e impregnaÃÃo foram utilizados na produÃÃo de catalisadores de TiO2 suportados em Ãxido de alumÃnio modificados com palÃdio. As amostras foram caracterizadas por diferentes tÃcnicas: AnÃlise termogravimÃtrica (TG), FluorescÃncia de Raios-X (FRX), difraÃÃo de Raios-X (DRX), isotermas de adsorÃÃo/dessorÃÃo de N2, reduÃÃo à temperatura programada (TPR) e microscopia eletrÃnica de varredura (MEV). A FRX mostrou a presenÃa de cÃlcio em todas as amostras, impureza proveniente da esponja de sÃntese, porÃm em teores abaixo de 0,5 % em massa. AtravÃs de DRX confirmou-se a formaÃÃo de TiO2 na fase anatase e de gama alumina As isotermas de adsorÃÃo de N2 mostram que os materiais sÃo mesoporosos com Ãrea superficial elevada e estreita distribuiÃÃo do diÃmetro mÃdio de poros. O perfil de TPR indica um consumo de H2 entre 50 e 90ÂC, correspondendo à reduÃÃo do Ãxido de palÃdio. Considerando a amplificaÃÃo empregada, o MEV sugere a morfologia esfoleada, a qual pode apresentar elevada Ãrea de contato com a molÃcula do corante. Os ensaios fotocatalÃticos mostram que a adiÃÃo de palÃdio ocasionou em melhor desempenho fotocatalÃtico e resultou em superior estabilidade frente Ãs reaÃÃes. Palavras chave: FotocatÃlise, PalÃdio, DiÃxido de TitÃnio. / In order to apply the photocatalytic decomposition of chemical substrates, the method of replication and impregnation were used in the production of TiO 2 catalysts supported on alumina modified with palladium. The samples were characterized by different techniques: Thermogravimetric analysis (TGA), X - Ray Fluorescence (XRF), X - ray diffraction (XRD), N2 adso rption/desorption isotherms , temperature programmed reduction (TPR) and scanning electron microscopy (SEM). The XRF did not detect significant mpurities from synthesis sponge and confirmed the insertion of Ti in the sample with the formation of phases Υ Al2O3, TiO2(anatase), revealed by XRD. The N2 adsorption /desorption isotherms show that mesoporous materials have high surface area and narrow distribution of the average pore diameter. The TPR profile indicates an H2 consumption between 50 and 90  C, corresponding to the reduction of palladium oxide. Considering the amplification used, the SEM suggests the esfoleada morphology, with high contact area with the dye molecule. The photocatalytic tests show that the addition of palladium did not result in improved photocatalytic performance, but resulted in greater stability in the photocatalytic activity.

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