| Journal: | Materials research |
| Database: | PERIÓDICA |
| System number: | 000312391 |
| ISSN: | 1516-1439 |
| Authors: | Melo, Rogerio A.A1 Giotto, Marcus V Rocha, Joao2 Urquieta Gonzalez, Ernesto A |
| Institutions: | 1Universidade Federal de Sao Carlos, Departamento de Fisica, Sao Carlos, Sao Paulo. Brasil 2Universidade de Aveiro, Departamento de Quimica, Aveiro. Portugal |
| Year: | 1999 |
| Season: | Jul |
| Volumen: | 2 |
| Number: | 3 |
| Pages: | 173-179 |
| Country: | Brasil |
| Language: | Inglés |
| Document type: | Artículo |
| Approach: | Experimental |
| English abstract | The aim of this work was to study the hydrothermal synthesis of Si and SiAlMCM-41 performed under both autogenic pressure and refluxing conditions. XRD data showed that the MCM-41 phase may be formed by both processes and that the synthesized material in the presence of Al and/or under reflux presents the hexagonally arrangement of less ordered mesopores. However, as verified by XRD and physisorption data, the order was improved with higher synthesis times. 29Si and 1H - 29Si C/P MAS NMR spectra showed that a great part of the Si atoms exists as silanol groups which originate resonance peaks at -110, -100 and -91 ppm. The presence of Al atoms may generate Si(3Si, Al) and Si(2Si, 2Al) environments which might be contributing to resonance peaks at -100 and -91 ppm. The 27Al MAS NMR spectrum of the as synthesized AlSiMCM-41 showed a resonance peak of tetrahedral framework aluminum close to 53 ppm and two others, one close to 14 ppm attributed to Al(H2O)6+3 species and the other a weak signal close to 32 ppm attributed to pentacoordinated Al. 27Al MAS NMR spectra of the calcined sample showed a peak at 0 ppm corresponding to an hexacoordinated extra-framework aluminum formed during calcination |
| Disciplines: | Ingeniería, Química |
| Keyword: | Ingeniería química, Química industrial, Cristales, Caracterización fisicoquímica, Síntesis química |
| Keyword: | Engineering, Chemistry, Chemical engineering, Industrial chemistry, Crystals, Physicochemical characteristics, Chemical synthesis |
| Full text: | Texto completo (Ver HTML) |
