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

This paper reports a variety of synthesis pathways leading to thermally sta ble mesoporous aluminum oxide phases, based on cooperative self-assembly of inorganic and surfactant species. All the mesostructured phases were obtai ned in aqueous media by hydrolysis and condensation of different inorganic aluminum reactants involving monomeric cations such as [Al(H2O)(6)](3+) and /or oligomeric cationic species such as Keggin aluminum clusters, in the pr esence of single (anionic or non-ionic) or mixed (cationic-anionic) surfact ant micelles, at pH values lower than the isoelectric point of alumina, typ ically 8-9, Selected anionic surfactants were dodecyl sulfate or carboxylic acids, optionally admired with small amounts of cetyltrimethylammonium bro mide, while the non-ionic surfactants belong to the polyethyleneglycol-phen ylether and the amine-N-oxide families. Most of the mesophases proved therm ostable and exhibited a regular porous structure. Strongly depending on the synthesis and calcination conditions, their mean pore diameters vary betwe en 8 and 60 Angstrom and their specific surface areas range between 300 and 820 m(2) g(-1). (C) 2000 Elsevier Science B.V, All rights reserved.