Conversão de glicerol sobre CaO/SiO2 dopado com prata e platina

• Autor(a) principal: Costa, José de Ribamar Macedo
• Data de Publicação: 2019
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Ceará (UFC)
• Texto Completo: http://www.repositorio.ufc.br/handle/riufc/59937
• topic: Glicerol; Óxido de cálcio; Óxido de silício; Acetol; Metanol

The growing environmental concern associated with the expectation of a decrease in oil reserves in the near future has intensified the need to change the world energy matrix, which is now moving towards sources and processes for the generation / use of renewable energy. In this context, the production of biofuels, such as biodiesel, has increased research efforts both to optimize the production processes of biodiesel and to take advantage of its by-products, especially glycerol, which is an excellent raw material for obtaining a great variety of high value-added oxygenated chemicals, useful in the chemical, petrochemical, pharmaceutical, cosmetic, polymer and food industries. These products were generally obtained through heterogeneous catalysis using multicomponent oxide catalysts. This study aimed to evaluate the catalytic activity of CaO/SiO2 doped with platinum and silver for the glycerol dehydration /hydrogenolysis reaction for the production of acrylaldehyde (acrolein) and hydroxyketone (acetol). The catalysts were obtained by polymer precursor method and characterized by DRX, MEV-EDS, Adsorption-N2, TPR, TPD-CO2 and DTG. The catalysts are composed mainly of CaO/SiO2, with non-porous particles with a mean diameter of 0.177 mm that undergo agglomeration, resulting in a mesoporous structure, with an average surface area of 45m2 g-1 and a pore diameter greater than 1000Å , thermally stable at temperatures up to 700°C for oxidizing atmospheres. In the catalytic tests performed on continuously operated, isothermal tubular reactors, the catalysts were stable in the reaction medium, with glycerol conversions of more than 50%, and the reaction temperature was as main products methanol (11%) and hydroxyketone (50%). Products such as 1,2-propanediol, 1,3-propanediol, 1-propanol, isopropanol, acetone were observed in smaller amounts with selectivity ranging from 1% to 4%. The activity of the catalysts was considered to be high, presenting activation energies (Ea) for the Pt0.2Ag0.2CaO/SiO2 of 21.0 kJmol-1, 26.68 kJmol-1 and 36.39 kJmol-1 for atmospheres of N2, H2 and CO2, respectively, in the temperature range of 250°C to 316°C.