Synthesis of mesostructured aluminophosphates using cationic templating

Abstract

Hexagonal (Hex-1, Hex-2 and Hex-3) and lamellar (L1 and L3) mesostructured aluminophosphates have been prepared at room temperature in the presence of a cationic surfactant. Transitions between different structures can be directed by modifying the behaviour of the surfactant and the degree of condensation of the inorganic component. The products differ in Al:P ratios, relative contents of 4- and 6-coordinate Al, degrees of condensation, template contents and thermal stabilities. The inorganic component in hexagonal and L3 products is less condensed than in L1 and L2 (previously synthesised at hydrothermal conditions) as evidenced by the predominant 6-coordination of Al and the low-field ³¹P NMR chemical shifts. Upon calcination, Hex-1 and Hex-2 give thermally stable mesoporous solids with a tubular pore arrangement. The pore diameter of the calcined hexagonal AlPO increases with the increased Al:P ratio.