Nano-sized AlPO۴-۵ 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 ۲ nm, they are classified as microporous materials. Synthesis of microporous materials is usually conducted by the high temperature treatment (۸۰-۲۰۰ °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 AlPO۴-۵ (AFI) crystals. The treatment involved three main steps: (۱) to prepare a synthesis gel and let it get well mixed, then filling autoclave with the gel and sealing it; (۲) crystallization at ۱۸۰ ◦C for ۶ h; and (۳) Calcination at ۶۰۰ ◦C for ۴ 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 AlPO۴-۵ crystals was about ۶۵ nm.

Keywords:

Nano-sized crystal , AlPO۴-۵ , Zeolite , Hydrothermal , Molecular sieve