Structural aspects of mesoporous AlPO4-5 (AFI) zeotype using microwave radiation and alumatrane precursor

A new route for preparation of mesoporous AlPO₄-5 (AFI) zeotype has been synthesized using alumatrane precursor, prepared from aluminum hydroxide and triisopropanolamine (TIS) by the oxide one pot synthesis (OOPS), via microwave technique using triethylamine (TEA) as a structure-directing agent. The influences of the reaction mixture composition, HF acid, water content and the crystallization temperature and time were investigated. The prepared materials were characterized using X-ray diffraction, SEM and BET. The results showed a mesoporous AlPO₄-5 zeotype having a uniform rod-like structure with surface area around 120–180 m²/g. The high crystallinity with narrow size distribution of crystals was obtained at a high amount of structure-directing agent (the mole ratio of TEA/Al₂O₃ = 3.5). The presence of fluorine ion retarded the nucleation and growth rate, leading to a bigger crystal size. The crystal of the AFI grew preferentially in the c-direction with the reaction time and the water content. The use of lower reaction temperature to obtain good crystalline material can be compensated by a longer reaction time.