Synthesis and crystal morphology control of AlPO4-5 molecular sieves by microwave irradiation

• AlPO4-5 molecular sieves with AFI-zeotype structures were prepared by microwave technique.
• The morphology of crystals could be controlled by the reaction conditions.
• Morphology transformation from plate-like hexagonal to rod-like hexagonal was observed by changing the concentration of HF.
• The aspect ratio of the AlPO4-5 molecular sieves increases with the increase of the solvent polarity.

AlPO4-5 molecular sieves have been synthesized by the hydrothermal and solvothermal reactions using triethylamine as a template, aluminum isopropoxide and orthophosphate as the aluminum and phosphorus resource under microwave irradiation. The influences of various experimental parameters, such as reaction time, reaction temperature and reaction power, have been systematically investigated. The morphology control of AlPO4-5 molecular sieves was achieved by changing the dosage of solvent and HF to control the solvent polarity and control the nucleation respectively. The products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and so on. The results show that the aspect ratio of the AlPO4-5 molecular sieves increases with the increase of the solvent polarity and with the increasing concentration of HF, the morphology of AlPO4-5 molecular sieves changes from hexagonal plate to hexagonal rod.

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