Materiais zeolíticos de estrutura MWW: síntese e caracterização
In this paper a synthesis parameters study was conducted in order to optimize the obteinment of MCM-22 (MWW structure) and increase its accessibility, getting higher external surface and generating mesopores. Syntheses with Si / Al = 15 and Si / Al = 50 ratios were performed under static conditio...
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| Formato: | Dissertação |
| Idioma: | por |
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Universidade Federal do Rio Grande do Norte
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| Endereço do item: | https://repositorio.ufrn.br/jspui/handle/123456789/20593 |
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| Resumo: | In this paper a synthesis parameters study was conducted in order to optimize the obteinment
of MCM-22 (MWW structure) and increase its accessibility, getting higher external surface
and generating mesopores. Syntheses with Si / Al = 15 and Si / Al = 50 ratios were performed
under static conditions at different temperatures and with seeds induction, which resulted in
MCM-22 pure and crystalline (Si / Al ratio = 15) after 3 days and Si / Al = 50 after 11 days.
The reduction of hexamethyleneimine content (HMI) was studied in the stirring synthesis and
a HMI reduction of 47% was possible through the mother liquor reuse, in addition, a specific
area of 481 m² / g has been obtained in the fourth synthesis day. Regarding the increase of
accessibility of the MCM-22 zeolite skeins of MCM-22 plates with about 2 μm were
obtained, through the use of dissolved silica, addition of seeds, increased temperature and
synthesis time of 2 days. A significant value of specific area was found for this material,
around 500 m² / g. Also with respect to the increase of MCM-22 accessibility, treatment with
oxalic acid concentration of 0.5 mol / L and silanization of proto-zeolitic units resulted in the
mesopores formation . Furthermore, silanization still favored reduction of 70 % in crystal size
and a specific area of 566 m² / g. |
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