Síntese e caracterização de óxido de alumínio e/ou silício através do método sol-gel proteico
In order to synthesize nanostructured materials with high porosity from a simple, renewable, efficient, low cost and high catalytic performance methodology, aluminum oxide and / or silicon oxide based solids were synthesized using the sol protein gel using porcine gelatin as an organic precursor...
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| Formato: | Dissertação |
| Idioma: | pt_BR |
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Brasil
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/28232 |
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| Resumo: | In order to synthesize nanostructured materials with high porosity from a simple,
renewable, efficient, low cost and high catalytic performance methodology, aluminum oxide
and / or silicon oxide based solids were synthesized using the sol protein gel using porcine
gelatin as an organic precursor and aluminum nitrate and / or tetraethyl orthosilicate as
inorganic precursors. The characterization was carried out through X-ray Fluorescence,
Thermogravimetry, X-ray Diffraction, Infrared Spectroscopy, Scanning Electron Microscopy,
Mercury Porosimetry, Nitrogen Sorption and catalytic tests (ethanol dehydration model
reaction). The X-ray Fluorescence proved the efficiency of the synthesis methodology
regarding the chemical composition of the oxides. The thermogravimetric results indicated the
total release of the organic material at the calcination temperature used and that the hybrid
material is more thermally stable than the outer ones. The X-ray diffractograms showed an
amorphous material profile characteristic of highly dispersed metal oxides. Infrared spectra
showed the presence of a hybrid material and gelatin structure characteristic bands prior to
calcination that disappeared into the solid spectrum after calcination indicating the loss of
organic matter after heat treatment and also exhibited MO stretching vibration in low
wavelengths after the calcination that are related to the metal oxides (SiO2 and Al2O3)
formed. The images acquired by Scanning Electron Microscopy suggested that the oxides
have a sponge-like morphology. This morphology was confirmed by the technique of
Mercury Injection and Nitrogen Sorption in which it was possible to observe that the material
has high hierarchical porosity and interesting texture properties, especially for materials
containing aluminum oxide and silicon oxide. The results of ethanol dehydration showed
higher selectivity to diethyl ether compared to ethylene while acetaldehyde showed no results.
From the reaction data, the following order of acid strength was obtained: 2 Si: Al> Si: 2Al>
Si: Al> Al, proving that the Si: Al ratio and the specific area influence this sequence. |
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