Crystal morphology control of AlPO4-11 molecular sieves by microwave irradiation

AlPO4-11 molecular sieves with morphologies of aggregated sphere, clump, faggot and rod were successfully synthesized by microwave irradiation using diisopropylamine as template. By adjusting the crystallization time, the morphology of the AlPO4-11 molecular sieves changed from sphere to clump and then to faggot. With the increasing concentration of HF, the morphology of AlPO4-11 molecular sieves changed from sphere to rod gradually, which exactly consisted with the variation of the XRD patterns. Slow nucleation rate caused by the chelated function of Al–F may be the main reason to direct the crystal growth on the special direction. Meanwhile, some control experiments including use of HCl and increasing the concentration of water also showed the same preferential growth of the crystals.