resumo
Using triblock copolymer Pluronic P123 as a structure-directing agent, water as solvent, tetraethyl orthosilicate (TEOS) and aluminium sulfate (Al(2)(SO(4))(3) 18H(2)O) as silica and aluminium sources, respectively, a series of Al-SBA-15 with well-ordered mesostructure has been hydrothermally synthesized up to high aging temperature through a one-step approach in an environmentally friendly mineral acid-free medium. The influence of some synthesis parameters such as Si/AI molar ratio (5-100), P123/Si molar ratio (0.0025-0.014) and aging temperature (363-443 K) on the properties of the resultant materials were investigated by powder X-ray diffraction (XRD), nitrogen adsorption-desorption at 77 K. transmission electron microscopy (TEM), and solid state (27)Al MAS NMR analyses. The textural properties of Al-SBA-15, such as specific surface area, pore volume and mesopore size, can be modified by simply adjusting those synthesis parameters. Solid state (27)Al MAS NMR results show direct evidence that aluminium is introduced onto the wall structure and located mainly at tetrahedrally coordinated sites. The structural ordering increases with increasing aluminium sulfate amount in the gel from Si/Al of 100-5, with the aluminium species playing an important role in the formation of the ordered mesostructure. The increase of aging temperature causes widening of mesopores, which are still highly ordered upon aging at 443 K. The procedure allows the formation, up to high reaction temperature, of aluminium incorporated SBA-15 exhibiting high structural ordering and hydrothermal stability. (C) 2011 Elsevier Inc. All rights reserved.
palavras-chave
MESOPOROUS MOLECULAR-SIEVES; TRIBLOCK COPOLYMER; NONIONIC TRIBLOCK; SILICA STRUCTURES; SBA-15 MATERIALS; ALUMINATION; PORES; ALUMINOSILICATES; TEMPERATURE; ENVIRONMENT
categoria
Chemistry; Science & Technology - Other Topics; Materials Science
autores
Lin, S; Shi, L; Carrott, MMLR; Carrott, PJM; Rocha, J; Li, MR; Zou, XD
nossos autores
João Rocha
Prof. Catedráticoagradecimentos
This work was financially supported by The Fundacao para a Ciencia e a Tecnologia (FCT, Portugal) under project PTDC/CTM/67314/2006 (FCOMP-01-0124-FEDER-007145) and Grant SFRH/BPD/26924/2006 (S. L.), with National and European funds (FEDER, program COMPETE of QREN). The NMR spectrometer is part of the National NMR Network and was purchased in the framework of the National Programme for Scientific Re-equipment, contract REDE/1517/RMN/2005, with funds from POCI 2010 (FEDER) and FCT. This study was also supported by the Swedish Research Council (VR), the Swedish Governmental Agency for Innovation Systems (VIN-NOVA) and the Goran-Gustafsson Foundation.