Zircônia sulfatada magnética: síntese, caractetização e aplicação na esterificação de óleos residuais

Abstract

In the present work the production of sulfated zirconia oxides without iron and with different amounts of iron was studied to be heterogeneous catalysts in the esterification reaction of the residual oil. To prepare the materials the hydrothermal synthesis route was used in the materials with presence of iron, the magnetite was added in proportions of 2.5%, 5% and 10% with respect to the precursor zirconia. For the pure zirconia material, the difference is that the precursor was added to the base without presence of magnetite. After the material was produced, the sulfation process was carried out by impregnation, each material was placed in contact with a solution of 3 mol L -1 of H2SO4 for three hours under ambient temperature. The materials were then washed, dried and calcined in the presence of N2 in the oven. The catalysts produced were characterized by Vibrational Spectroscopy in the Infrared Region (FTIR), Thermogravimetric Analysis (TG), X-Ray Diffraction (XRD), Raman Spectroscopy, Scanning Electron Microscopy (SEM), X-ray Fluorescence (FRX) and acidity test. It was observed that the materials exhibited good thermal stability and small crystallite size. It was possible to prove the sulfation by the analysis of Spectroscopy in the Infrared Region, Raman Spectrocopy and increase in acidity. Sulfation decreased the crystallinity of the materials, the size of the crystallite and increased the materials acidity, but did not alter the zirconia phases, being possible to identify the zirconia in the tetragonal and monocyclic phases. The presence of iron in its segregated phase was identified by XRD analysis. It was possible to notice from FRX analysis that the amount of iron increased in the materials and the amount of zirconia and sulphate remained constant. In the esterification reaction of acetic acid, the sulphated materials showed higher conversion than the materials that had not undergone the sulfation process, so the sulfated materials were chosen to be characterized and tested in the esterification reaction of the residual oil. Sulphated materials showed high conversions of fatty acids to esters. The material that obtained the highest conversion was the material ZrS / 10Fe, with 10% of iron, converting 87%. Thus, the synthesized and studied materials present catalytic potential to be used whit catalyst in the esterification reaction of residual oils.