Uso de lama vermelha e glicerol como precursores de materiais com propriedades redox

Abstract

The red mud (RM) is the main residue generated during bauxite processing to produce alumina (Al2O3) in the Bayer process. Due to its highly alkaline nature, as well as to the large amount generated, it presents itself as an environmental liability, providing high risks to neighboring populations and environmental contamination. The biodiesel industry also faces some challenges due to the generation of a large amount of glycerol as a byproduct. Although glycerol is widely used as a feedstock in various industrial applications, the material is, however, generated in quantities greater than the demand. In this work the preparation of materials based on RM and glycerol were done that were tested as catalysts in different applications. The RM was previously submitted to a neutralization process using CO2 (RM_CO2) and submitted to impregnation with 5% by mass of Fe and 5% by mass of crude glycerol (RM_FG).After impregnation, thermal treatments were carried out in an oxidizing atmosphere (RM_O2) and in an inert atmosphere (RM_N2).In order to compare and analyze catalytic potential were used the precursors: RM_CO2, RM_Fe, RM_Gli and RM_FG. Through the results obtained by the characterizations, it was verified the presence of phases of iron oxides like hematite, magnetite and goethite, also aluminosilicates.The results of the degradation tests showed that the material RM_O2 showed to be superior in the capacity of adsorption / degradation of the organic molecule AM, whereas the material RM_N2 showed superior against the molecule of Phenol.Precursors showed lower activity in all tests performed.There was no leaching of the material and these showed magnetic and amphiphilic properties.The materials produced were also studied as catalysts in the conversion of alcohols, using isopropanol, 1-butanol and ethanol as the model molecules. RM was attractive in the conversion of alcohols, RM_O2 showed conversion of 87% of isopropanol, 59% of 1-butanol and 61% of ethanol; with formation of 44% acetone, 22% butanal and 29% acetaldehyde, respectively. The RM_N2 converted 98% of isopropanol, 83% of 1-butanol and 53% ethanol, forming 57% acetone, 5% butanal and 10% acetaldehyde, respectively. Stability tests were also performed, showing that the materials remain active for more than 36 continuous hours of reaction without loss of activity.The results show the potential in the use of waste, such as RM and glycerol, in the development of new materials that can be used with catalysts in various reactions of industrial and environmental interest.