Made available in DSpace on 2014-12-17T15:42:09Z (GMT). No. of bitstreams: 1 SolangeAQ_TESE.pdf: 2741616 bytes, checksum: ad21da6882b166123a02d610e3d096ef (MD5) Previous issue date: 2009-08-06 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The nanostructured molecular sieve SBA-15 was synthesized by the hydrothermal method, and modified with lanthanum with Si/La molar ratios of 25, 50, 75 and 100. The materials were evaluated as catalysts for the cracking of n-hexane model reaction. Type SBA- 15 and LaSBA-15 mesoporous materials were synthesized using tetraetilortosilicato as a source of silica, hydrochloric acid, heptahydrate lanthanum chloride and distilled water. Pluronic P123 triblock. polymer was used as structure template. The syntheses were carried out by 72 hours. The obtained SBA-15 samples were previously analyzed by thermogravimetry, in order to check the conditions of calcination for removal of organic template. Then, the calcined materials were characterized by X-ray diffraction, infrared spectroscopy, adsorption and desorption of nitrogen, scanning electron microscopy and X-ray microanalysis by dispersive energy. The acidity of the samples was determined using adsorption of n-bulinamina and desorption followed by thermogravimetry. It was found that the hydrothermal synthesis method was suitable for the synthesis of the SBA-15 mesoporous materials, with an excellent degree of hexagonal ordering. The reactions of catalytic cracking of n-hexane were carried out using a fixed bed continuous flow microreactor, coupled on-line to a gas chromatograph. From the catalytic evaluation, it was observed that the mesoporous materials containing lanthanum showed different results for the reaction of cracking of nhexane compared to the unmodified mesoporous material SBA-15. As a result of cracking was obtained as main products hydrocarbons in the range of C1 to C5. The catalyst that showed better properties in relation to the acidity and catalytic activity was LaSBA-15 with the ratio Si/La = 50 / A peneira molecular nanoestruturada SBA-15 foi sintetizada pelo m?todo hidrot?rmico, e modificada com lant?nio com raz?es molares Si/La de 25, 50, 75 e 100. Os materiais obtidos foram avaliados como catalisador para a rea??o modelo de craqueamento de n-hexano. Os materiais mesoporosos tipo SBA-15 e LaSBA-15 foram sintetizados utilizando tetraetilortosilicato, como fonte de s?lica, ?cido clor?drico, cloreto de lant?nio heptahidratado e ?gua destilada. Como direcionador estrutural foi utilizado copol?mero tribloco Pluronic P123. As s?nteses foram realizadas durante 72 horas. As amostras de SBA-15 modificadas foram avaliadas por termogravimetria para verificar as condi??es de calcina??o para remo??o do direcionador org?nico. Ap?s a retirada do direcionador as amostras de SBA-15 modificadas com diversas raz?es Si/La (25, 50, 75 e 100) foram caracterizadas por an?lises por difra??o de raios-X, espectroscopia na regi?o do infravermelho, adsor??o e dessor??o de nitrog?nio, microscopia eletr?nica de varredura e microan?lise de raios X por energia dispersiva. A acidez das amostras foi determinada utilizando adsor??o de n-bulinamina seguido de dessor?ao por termogravimetria. Verificou-se que o m?todo de s?ntese hidrot?rmica foi adequado ? s?ntese dos materiais mesoporosos modificados com excelente grau de ordena??o hexagonal. As rea??es de craqueamento catal?tico do n-hexano foram realizadas em um microreator catal?tico de leito fixo com fluxo cont?nuo acoplado em linha com um cromat?grafo a g?s. A partir da avalia??o catal?tica, foi observado que os materiais mesoporosos contendo lant?nio foram mais ativos que o SBA-15, para a rea??o de craqueamento do n-hexano, obtendo-se como produto hidrocarbonetos na faixa de C1 a C5. O catalisador que apresentou melhores propriedades, em rela??o ? acidez e a atividade catal?tica foi o sintetizado com a raz?o Si/La=50