Nanosized AlPO₄-5 Molecular Sieves and Ultrathin Films Prepared by Microwave Synthesis

Nanosized AlPO 4 -5 molecular sieves and submicron AlPO 4 -5 films were synthesized by microwave treatment of aluminophosphate precursors. The effects of the chemical composition of the initial solution and the conditions of microwave treatment of aluminophosphate precursors on the synthesis of nanosized AlPO 4 -5 molecular sieves were investigated. The syntheses were performed under hydrothermal conditions in a microwave oven at temperatures ranging from 90 to 160 °C, using various concentrations of H 2 O and organic template and varying aging times. The resulting bulk products were analyzed using X-ray diffraction, scanning electron microscopy, thermogravimetry, dynamic light scattering, and nitrogen sorption. Optimal conditions for the preparation of nanosized molecular sieve crystals were found. Thin films of AlPO 4 -5 on acoustic wave devices were also prepared, composed of a molecular coupling layer, AlPO 4 -5 seed crystals, and a homogeneous porous film formed by microwave treatment of an aluminophosphate precursor. The initial mixture composition and microwave conditions affect the thickness and the orientation of the zeolite crystals in the films. Sorption isotherms for n -hexane and cyclohexane in these AlPO 4 -5 films are reported.