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Ordered aluminosilicate mesostructures having a SiO 2 /Al 2 O 3 ratio near 5 were prepared using a surfactanttemplated synthesis. The solid structures were analyzed by scanning electron microscopy (SEM), nitrogen sorption to determine pore volume and pore sizes, powder X-ray diffraction (PXRD), thermal desorption of a chemisorbed base to determine strong acid site density, and magic-angle-spinning (MAS) NMR spectroscopy for the 27 Al and 29 Si nuclei. We were successful in synthesizing a mesoporous aluminosilicate having a SiO 2 / Al 2 O 3 ratio near 5 when the source of the aluminum ion was Al hydroxide and the surfactant was cetyltrimethylammonium cation (C 16 TMA + ). The uncalcined samples showed only tetrahedral aluminum as confirmed by 27 Al MAS NMR. When the pH of the synthesis gel was 10.5, the mesostructure developed a pore volume of 0.59 cm 3 /g with an average pore diameter of 2.2 nm. The pore volume was less at pH values other then 10.5 (e.g., for pH 12.6 and 8.1, the pore volumes were 0.50 and 0.43 cm 3 /g, respectively). The aluminosilicate mesostructure showed Brønsted and Lewis sites as confirmed by the IR vibrational spectroscopy of chemisorbed pyridine. The mesostructure Brønsted acid site density was 0.36 µmol H + /m 2 -solid, based on Brønsted acid site titration by isopropylamine temperature-programmed desorption. It was similar to that observed for an amorphous alumina-silica having a SiO 2 /Al 2 O 3 ratio near 6. However, the mesostructure Brønsted site density per unit mass was much lower than that measured for an acidic Y-faujasite with a SiO 2 /Al 2 O 3 ratio of 2.75.

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