Synthesis strategies leading to surfactant-assisted aluminas with controlled mesoporosity in aqueous media

• Published in: Microporous and mesoporous materials 2000-04, Vol.35, p.597-607
• Main Authors: Valange, S., Guth, J.-L., Kolenda, F., Lacombe, S., Gabelica, Z.
• Format: Article
• Language: English
• Subjects: Anionic surfactant templates; Aqueous media synthesis; Controlled mesoporosity; Keggin salts; Mesoporous alumina
• ISSN: 1387-1811; 1873-3093
• DOI: 10.1016/S1387-1811(99)00253-X

This paper reports a variety of synthesis pathways leading to thermally stable mesoporous aluminum oxide phases, based on cooperative self-assembly of inorganic and surfactant species. All the mesostructured phases were obtained in aqueous media by hydrolysis and condensation of different inorganic aluminum reactants involving monomeric cations such as [Al(H 2O) 6] 3+ and/or oligomeric cationic species such as Keggin aluminum clusters, in the presence of single (anionic or non-ionic) or mixed (cationic–anionic) surfactant micelles, at pH values lower than the isoelectric point of alumina, typically 8–9. Selected anionic surfactants were dodecyl sulfate or carboxylic acids, optionally admixed with small amounts of cetyltrimethylammonium bromide, while the non-ionic surfactants belong to the polyethyleneglycol–phenylether and the amine- N-oxide families. Most of the mesophases proved thermostable and exhibited a regular porous structure. Strongly depending on the synthesis and calcination conditions, their mean pore diameters vary between 8 and 60 Å and their specific surface areas range between 300 and 820 m 2 g −1.