Nano-sized AlPO4-5 Crystals: Synthesis and characterization

Molecular sieves and zeolites are materials whose crystalline frameworks form nanometer or subnanometer pores. A variety of different crystal structures are known having a range of pore sizes. Because the pore sizes are usually smaller than 2 nm, they are classified as microporous materials. Synthesis of microporous materials is usually conducted by the high temperature treatment (80-200 °C) of aqueous synthesis gels. The process of heating aqueous mixtures to elevated temperatures for crystallization is typically described as hydrothermal synthesis. A hydrothermal treatment has been used to synthesize nano-sized AlPO4-5 (AFI) crystals. The treatment involved three main steps: (1) to prepare a synthesis gel and let it get well mixed, then filling autoclave with the gel and sealing it; (2) crystallization at 180 ◦C for 6 h; and (3) Calcination at 600 ◦C for 4 h to separate template materials. The crystals have been structurally characterized using X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray analysis (EDAX). The analyses show an acceptable fitness to the referred pattern. The SEM analysis and Scherer equation revealed that the size of the obtained AlPO4-5 crystals was about 65 nm.