Synthesis and characterization of a novel layered aluminophosphate of kanemite-like structure

The synthesis and structural characterization of a novel layered aluminophosphate (named AlPO-ntu) with a structure mimicking to that of the naturally occurring silicate mineral kanemite are described. This new compound was synthesized using the hydrothermal method and n-alkylamines as templates. On the basis of the results of thermal and elemental analysis, the chemical formulas were determined to be AlP0(3)(0H)(2)[NH2(CH2)(x)CH3] (x = 3, 5, and 7) for templates of butyl-, hexyl-, and octylamines, respectively, Solid-state Al-27 and P-31 MAS NMR spectra showed that both elements were in tetrahedral coordination. FT-IR spectra and ion-exchange studies revealed that three of the tetrahedra oxygen are bridging between Al and P atoms. The fourth oxygen, pointing away from the aluminophosphate sheet, hears either a proton when adhering to aluminum or an alkylammonium ion when adhering to phosphorus. The alkylammonium ions are ready for ion-exchange, while the protons attached to the Al-O terminals are not exchangeable with alkaline ions. Similar to kanemite of single-layered structure, the aluminophosphate layers are able to reorganize and condense to form porous materials when the interlayer alkylammonium ions are exchanged by surfactant cations.