Transformation of layered polyoxometallate cluster salts into mesoporous materials

A new approach to the formation of mesoporous materials has been developed, based on a two-step "salt-gel" synthesis, in which mesoporous aluminophosp hates, galloaluminophosphates, and aluminosilicates have been created. The first step involves pre-organizing charged inorganic clusters (MO4Al12(OH)( 24)(H2O)(12)(7+), M = Al Or Ga) into a layered mesoscopic material with opp ositely charged organic surfactant molecules. In the second step, phosphate or silicate linker molecules are added, which diffuse through the cluster/ surfactant salt, react with the clusters, and transform the layered precurs or into a non-lamellar mesostructured material. Removal of the surfactant f rom the alumino- and galloaluminophosphates by anion-exchange and from the aluminosilicates by calcination results in mesoporous materials with BET su rface areas up to 630, 455, and 431 m(2)/g, respectively. Direct condensati on by calcination of polyoxoaluminate cluster salts without additional link ers produces nanometer-sized one-dimensional strings. (C) 1999 Elsevier Sci ence Ltd.