Aluminum-Containing Mesostructural Materials

This article reviews syntheses of mesoporous aluminosilicates and aluminum oxides based on surfactant templating methods. The incorporation of aluminum in the silicate frameworks generates acid sites and ion-exchange sites. Both, tetrahedral framework aluminum and octahedral extraframework aluminum can be present, depending on the aluminum precursor used. The aluminum-containing structures tend to be less ordered than their purely siliceous analogs. Dealumination plays a significant role during template removal. Other methods for the synthesis of mesoporous aluminum-containing sieves are based on the structural transformation of kanemite, and on cluster precursors which may be connected by self-condensation or by condensation with silicate bridges. Purely aluminous mesostructures can be prepared with neutral templates or by condensing Keggin-like aluminum clusters in an ordered salt with an anionic surfactant.