Ionothermal synthesis of AlPO4-34 molecular sieves using heterocyclic aromatic amine as the structure directing agent

AlPO4-34 was synthesized ionothermally in 1-butyl-3-methyl imidazolium bromide using heterocyclic aromatic amine as the structure directing agent (SDA). The as-synthesized products were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), nuclear magnetic resonance spectroscopy (NMR) and thermal gravimetric (TG) analysis. The factors affecting the crystallization were investigated. The results show that methyl-substituted heterocyclic aromatic amines can effectively direct to form AlPO4-34 and reside in the channel solely. Meanwhile, the ionic liquid need not be consumed, it merely acts as a solvent. Hydrofluoric acid plays a crucial role in the synthesis process as a mineralizer. The morphology and crystallinity of the product can be controlled by the dosage of the SDA and the crystallization temperature. The synthesized product shows a good thermal stability, and maintains a very good crystalline structure after calcination at 550 °C in air.