Thermal study of NaP zeolite with different morphologies

NaP zeolites samples with different morphologies were successfully synthesized and their thermal behaviors were fully characterized by in situ HT-XRD, IR spectrum, and TG-DSC techniques. It was found that the cubic zeolite NaP phase underwent the same phase transitions, despite their different morphologies. During the whole heating process, they first underwent a minor phase transition into the tetragonal phase at 200 °C. Then they were gradually converted into the phillipsite phase between 400 and 700 °C. Finally, a very stable NaAlSiO 4 nepheline phase formed when the calcination temperature reached 800 °C, which would be kept even after the sample was cooled to room temperature. Although samples with different morphologies had similar phase transitions, they did have different thermal stability as proved by the TG-DSC study.