Título: | SYNTHESIS AND CHARACTERIZATION OF CO-FE NANOCRYSTALS SUPPORTED ON MESOPOROUS SILICAS FOR THE FISCHER-TROPSCH SYNTHESIS | ||||||||||||||||||||||||||||||||||||
Autor: |
LAURINDA FATIMA DA FONSECA PEREIRA GUIMARAES BRAGANCA |
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Colaborador(es): |
MARIA ISABEL PAIS DA SILVA - Orientador |
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Catalogação: | 20/JUL/2010 | Língua(s): | PORTUGUESE - BRAZIL |
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Tipo: | TEXT | Subtipo: | THESIS | ||||||||||||||||||||||||||||||||||
Notas: |
[pt] Todos os dados constantes dos documentos são de inteira responsabilidade de seus autores. Os dados utilizados nas descrições dos documentos estão em conformidade com os sistemas da administração da PUC-Rio. [en] All data contained in the documents are the sole responsibility of the authors. The data used in the descriptions of the documents are in conformity with the systems of the administration of PUC-Rio. |
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Referência(s): |
[pt] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=15921&idi=1 [en] https://www.maxwell.vrac.puc-rio.br/projetosEspeciais/ETDs/consultas/conteudo.php?strSecao=resultado&nrSeq=15921&idi=2 |
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DOI: | https://doi.org/10.17771/PUCRio.acad.15921 | ||||||||||||||||||||||||||||||||||||
Resumo: | |||||||||||||||||||||||||||||||||||||
In this work, cobalt and iron bimetallic samples supported on SBA-15 or HMS mesoporous sílicas were prepared by incipient wetness impregnation. Cobalt nitrate and iron salts were used to obtain samples containing 25 wt% total of metal content. Also, a series of supported monometallic cobalt or iron samples were synthesized, with the same metal loading, and compared to bimetallic ones. In order, to investigate the effect of different templates, a series of HMS sílicas have been prepared using two types of structure direction: dodecylamine (DDA) and tetradecylamine (TDA). The samples were cheracterized by N(2)-physisorption, X-ray diffraction (XRD), temperature programmed reduction (TPR), transmission electron microscopy (TEM), H(2) chemisorption and X-ray photoelectron spectroscopy (XPS) analysis. The amount of incorporated metal was estimated by atomic absorption spectroscopy (AAS). The supports were, also, characterized by thermogravimetric (TGA), as well as differential thermal (DTA) analyses. The TGA/DTA curves showed that the templates were mainly removed until 700 K. The textural properties revealed that after metal introduction to SBA-15 support, specific area, pore volume and pore diameter decreased in a lesser extension for the bimetallic sample compared to monometallic ones. XRD measurements detected the formation of Co(3)O(4) and CoFe(2)O(4) phases for all bimetallic samples. For Co-Fe/HMS (TDA) sample, the a-Fe(2)O(3) phase formation and a higher Co(3)O(4)/CoFe(2)O(4) crystallite sizes were also observed. The wall thickness valour for HMS supports was higher than previously reported values, suggesting more stable materials. The TPR profiles indicated similar behavior between bimetallic and monometallic samples. In case of cobalt oxide on bimetallic sample, higher reduction temperatures were indicated compared to monometallic ones for HMS (TDA) support. A higher interaction metal-support was showed for Co-Fe/SBA- 15. According to hydrogen chemisorption, the bimetallic samples dispersions were higher than iron monometallic and lower than cobalt monometallic samples. From TEM microphotografs, it was observed a lesser fraction of agglomerates to Co-Fe/SBA-15 than Co-Fe/HMS (DDA) sample. XPS spectrum of Co2p region indicated the presence of Co(3)O(4) for the bimetallic sample, Co-Fe/HMS (DDA). The Fe-Co/HMS (DDA) bimetallic catalyst showed higher C(5+) and alcohols selectivities than Fe/HMS (DDA) on the Fischer-Tropsch reaction. Also, the bimetallic cobalt and iron based catalyst supported on HMS (DDA) recorded a higher value for the chain growth parameter (a) than Co-Fe/SBA-15. Both bimetallic catalysts exhibited highter selectivities (%) for lighter fractions, C2-C4.
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