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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

S?ntese, caracteriza??o de ?xido de alum?nio a partir de esferas h?bridase aplica??o na convers?o do glicerol: influ?ncia do grau de substitui??o e polimeriza??o da carboximetilcelulose

Silva, Monickarla Teixeira Pegado da 23 February 2016 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-08-26T23:16:09Z No. of bitstreams: 1 MonickarlaTeixeiraPegadoDaSilva_DISSERT.pdf: 2972749 bytes, checksum: 333ef217ee5461818b38fff8de7cfdeb (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-08-31T00:12:48Z (GMT) No. of bitstreams: 1 MonickarlaTeixeiraPegadoDaSilva_DISSERT.pdf: 2972749 bytes, checksum: 333ef217ee5461818b38fff8de7cfdeb (MD5) / Made available in DSpace on 2016-08-31T00:12:48Z (GMT). No. of bitstreams: 1 MonickarlaTeixeiraPegadoDaSilva_DISSERT.pdf: 2972749 bytes, checksum: 333ef217ee5461818b38fff8de7cfdeb (MD5) Previous issue date: 2016-02-23 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior (CAPES) / Suportes catal?ticos ? base de ?xido de alum?nio foram sintetizados pelo m?todo e esferas h?bridas utilizando carboximetilcelulose (CMC) como precursor org?nico (template) e nitrato de alum?nio como precursor inorg?nico. As caracteriza??es foram realizadas por an?lises de termogravimetria (TG), difra??o de raios-X (DRX), espectroscopia no infravermelho por transformada de fourier (FTIR), microscopia eletr?nica de varredura (MEV) e fisissor??o N2. Os materiais sintetizados foram testados na rea??o de convers?o do glicerol em fase g?s. Os estudos da s?ntese indicaram que as caracter?sticas do biopol?mero (grau de substitui??o e de polimeriza??o) influenciam diretamente no valor m?ximo da rela??o entre o precursor org?nico e inorg?nico para a forma??o das esferas h?bridas. As propriedades f?sico-qu?micas do material final (cristalinidade, porosidade, ?rea espec?fica e morfologia) mostraram uma depend?ncia direta com as propriedades do biopol?mero (grau de substitui??o e de polimeriza??o), indicando a versatilidade desta rota s?ntese. Os espectros de FTIR confirmaram a forma??o de um material h?brido quando se compara o espectro da CMC pura com os s?lidos obtidos ap?s a secagem. Os resultados de DRX mostraram um perfil de material amorfo para algumas amostras. Para alguns s?lidos foi poss?vel identificar a forma??o de uma fase cristalina relacionada com a alumina hidratada, ?xido de alum?nio e ?xido de cobre. As imagens obtidas por MEV indicaram a forma??o de um material com morfologia semelhante a uma esponja ap?s a calcina??o, caracter?stico de um s?lido altamente poroso. O perfil de adsor??o/dessor??o de N2 confirma a forma??o de materiais contendo micro-mesoporos com uma ?rea espec?fica entre 50-162 m2.g-1 para os suportes e 112-303 m2.g-1 para os catalisadores com cobre, indicando um aumento ?rea ap?s a adi??o do Cu por impregna??o devido a redissolu??o e recristaliza??o da fase alumina. Testes catal?ticos indicaram que os ?xidos s?o ativos e seletivos para a convers?o do glicerol (92-15%) a bioprodutos de alto maior valor agregado, confirmando a viabilidade do m?todo de s?ntese. / Catalytic supports based on aluminum oxide were synthesized by the method of hybrid spheres using carboxymethylcellulose (CMC) as organic precursor (template) and aluminum nitrate as inorganic precursor. The characterizations were performed by thermal chemical analysis (TGA), X-Ray diffraction (XRD), fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and N2 physisorption. The study of synthesis indicated that the characteristics of the biopolymer (degree of substitution and polymerization) directly influence on the maximum value of the ratio between the organic and inorganic precursor for the formation of hybrid spheres. The physicochemical properties of the final material (crystallinity, porosity, surface area and morphology) showed a direct dependence on the biopolymer properties (degree of substitution and polymerization), indicating the versatility of this synthesis route. The FTIR spectra confirm the formation of a hybrid material when comparing the pure CMC spectrum with the obtained solids after drying. The XRD results show a profile of amorphous and crystalline material for the different samples. For some solids were possible to identify the formation of a crystalline phase related to the hydrated alumina, aluminium oxide and copper oxide. The images obtained by SEM analysis showed the formation of a material with sponge-like morphology after calcination, characteristic of highly porous solid. The N2 adsorption/desorption isotherm profile confirms the formation of micro-mesoporous materials with a specific surface area between 50-162 m2.g-1 for the supports and 112-303 m2.g-1 for the copper-based catalysts, indicating an increase in the area after the addition of Cu by impregnation due to redissolution and recrystallization of alumina phase. Catalytic tests were tested in the glycerol conversion reaction (92-15%) to added value products in order to confirm their real viability.

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