| Texto completo | |
| Autor(es): |
Lima, Erika T. L.
;
Rodrigues, Mariana V.
;
do Nascimento, Luis A. S.
;
Zamian, Jose Roberto
;
da Costa, Carlos E. F.
;
Pastore, Heloise O.
;
da Rocha Filho, Geraldo N.
Número total de Autores: 7
|
| Tipo de documento: | Artigo Científico |
| Fonte: | Microporous and Mesoporous Materials; v. 334, p. 11-pg., 2022-02-28. |
| Resumo | |
In this study, SAPO-5 having a high silicon content was synthesized and further modified by functionalization with sulfonic acid groups using 3-mercaptopropyltrimethoxysilane (MTPS) as a precursor. In particular, we focused on the effect of water on the organofunctionalization process using SAPO-5 either dehydrated under vacuum (S5-SO3H/Vac) or without any thermal pretreatment (S5-SO3H). Using X-ray diffractometry, inductively coupled plasma-optical emission spectroscopy, elemental analysis of carbon, nitrogen, hydrogen and sulfur, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Si-29, Al-27, P-31, and C-13 NMR spectroscopy, it was possible to identify important structural differences in the obtained hybrid materials. The results showed that S5-SO3H has a Si:S molar ratio five times larger than that of S5-SO3H/Vac. The presence of T(m )sites (organic-modified silica sites, Si-C bonds), as revealed by Si-29 MAS-NMR measurements, suggests that the organic pending groups are bonded covalently to the Si-OH groups in the SAPO-5 network during silanization. Further differences between the material obtained under dry conditions and that prepared from hydrated SAPO-5 were revealed by measuring the acidity via potentiometric titration: S5-SO3H was 40% more acidic than S5-SO3H/Vac. Both materials were also tested for their catalytic oleic acid esterification ability. Although the turnover frequency of S5-SO3H/Vac was four times higher than that of S5-SO3H, its conversion after five sequential cycles dropped from 97.4 to 28.3%. In contrast, S5-SO3H yielded a conversion of 84.4%, starting from 99.4%, after the same number of cycles; thus, microporous SAPO-5 is a promising catalyst support for reactions involving bulky molecules such as oleic acid. (AU) | |
| Processo FAPESP: | 14/06942-0 - Sólidos lamelares nanoestruturados como catalisadores ácidos, básicos e redox |
| Beneficiário: | Heloise de Oliveira Pastore |
| Modalidade de apoio: | Auxílio à Pesquisa - Temático |
| Processo FAPESP: | 18/18494-3 - Desenvolvimento de métodos de caracterização de acidez de sólidos lamelares e zeólitos em meio aquoso |
| Beneficiário: | Mariana Veiga Rodrigues |
| Modalidade de apoio: | Bolsas no Brasil - Pós-Doutorado |