Incorporation of high aluminum contents into the silica framework of SBA-15 was achieved by treating SBA-15 with an aqueous (NH4)(3)AlF6 solution at room temperature under alkaline conditions. Characterization by powder X-ray diffraction (XRD). N-2 adsorption-desorption, transmission electron microscopy (TEM), FTIR, and multinuclear solid-state NMR measurements was carried out to evaluate the efficiency of this alumination method. Al-27 magic angle spinning (MAS). 1H/Al-27 TRAnsfer of Population in DOuble Resonance (TRAPDOR) NMR, and cumene cracking measurements demonstrated that the aluminated SBA-15 materials contained exclusively tetrahedrally coordinated aluminum and exhibited well-developed Bronsted acidity. A high level of framework aluminum substitution, up to an Si/Al ratio near 5, without any significant loss in the textural properties of SBA-15. was achieved via the present post-synthesis route. F-19 MAS NMR was helpful in gaining more insights into the mechanism of the present alumination process, (c) 2005 Elsevier B.V. All rights reserved.