Synthesis of ordered aluminophosphate and galloaluminophosphate mesoporous materials with anion-exchange properties utilizing polyoxometalate cluster/surfactant salts as precursors

Ordered nonlamellar mesoporous aluminophosphates and galloaluminophosphates have been synthesized by introducing phosphate linking groups to cluster/surfactants salts of prearranged AlO4Al12(OH)(24)(H2O)(12)(7+) (Al-13) and GaO4Al12(OH)(24)(H2O)(12)(7+) (GaAl12) tridecamers. The Al-13 and GaAl12 polyoxacations forma layered mesoscopic salt with The anionic surfactant sodium dodecylsulfate. Upon the reaction with a buffered hydrogen phosphate/dihydrogen phosphate solution the layers of clusters are transformed into a nonlayered, neatly hexagonal mesoscopic phase. Removal of the surfactant from the alumino- and galloaluminophosphates by anion-exchange results in mesoporous materials with BET surface areas up to 630 and 455 m(2)/g, respectively. FT-IR and Al-27 and P-31 MAS-NMR as well as Al-21-->P-31 cross-polarization experiments indicate that the phosphate treatment results in the formation of new bonds between aluminate and phosphate species. A fraction of the clusters are transformed leading to an increase in the number of tetrahedral aluminate groups in the product. Multiple anion-exchange,e.g., with acetate, dichromate, or naphthol yellow S ions, is possible in these open mesoporous structures, which form a new class of inorganic anion-exchangers.