Al2O3-TiO2 sulfatado como catalisador heterogêneo para a transesterificação de óleos vegetais

• Ano de defesa: 2017
• Autor(a) principal: Henrique, Raphael Santos [UNIFESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Paulo
• Palavras-chave em Português: Sulfated metallic oxides; Sulfated TiO2; Sulfated Al2O3; Transesterification; Superacids; Óxidos metálicos sulfatados; TiO2 sulfatado; Al2O3 sulfatado; Transesterificação; Superácidos
• Link de acesso: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=5008262; http://repositorio.unifesp.br/handle/11600/49983

Due to its high acidity properties, sulfated metallic oxides can be used as heterogeneous catalysts in different chemical reactions. The aim of this work was to prepare an aluminum and titanium based sulfated mixed oxide (SO42-/Al2O3-TiO2) and test it in the soybean oil transesterification. Sulfated oxides were prepared utilizing sol-gel method in one-step (in situ), with some variations in the preparations. In two of these syntheses, the aluminum precursor and the Al2O3 molar content were varied in the mixed oxides composition, without using the structure-directing polymer. In the other two, the structure-directing polymer Pluronic P123 was used, one synthesis to form the SO42-/Al2O3-TiO2 mixed oxide (50% mol of metal) and the other to form the SO42-/TiO2 oxide. In the two first preparations was observed that bohemita sol is the best precursor to SO42-/Al2O3-TiO2 oxide, in comparison with titanium isopropoxide, allowing the preparation of SO42-/Al2O3-TiO2 oxide with better surface area (205-215 m²/g) in comparison with SO42-/TiO2 oxide (172 m²/g). It was also noted that mixed oxides with a lower content of Al2O3 in composition showed better structural and textural properties as the coordinated sulfated in the chelate form and more crystalline oxides, specially A-5 oxide. In other two preparations, with Pluronic P123, it was verified that SO42-/TiO2 oxide showed better surface area (254,1 m²/g) in comparison with SO42-/Al2O3-TiO2 oxide prepared with polymer (133,9 m²/g) and SO42-/TiO2 oxide prepared without Pluronic P123, showing the sulfate well-coordinated in the oxide structure. In catalytic tests, the SO42-/Al2O3-TiO2 oxide prepared without Pluronic P123 and 5% Al2O3 mol content in composition (A-5) allowed the formation of 72,03% of methyl esters after two hours of reaction. The SO42-/TiO2 oxide prepared with Pluronic P123 also allowed the formation of 73, 53% of methyl esters after two hours of reaction. The catalytic activity was closed linked with the sulfate coordination in chelate form, that allow the existence of more evident Lewis acid sites and strong acid sites in TiO2 and Al2O3-TiO2 oxides structures.