Effects of Synthesis Parameters on Hydrothermal Synthesis of NaA Zeolite

摘要

In this research, NaA zeolite samples were synthesized from aluminosilicate solution through hydrothermal method. The effects of different parameters such as the SiO_2/Al_2O_3, OH-/Si and H_2O/Na_2O molar ratios of the initial gel solution, crystallization time and temperature on the crystallinity and morphology of the synthesized zeolites were investigated. The final products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser particle size analyzer. The experiment results indicated that the SiO_2/Al_2O_3 molar ratio had influence on morphology and size of the synthesized zeolites, the optimum range of SiO_2/Al_2O_3 molar ratio for synthesizing NaA zeolite was 1.5-2. Alkalinity (OH-/Si and H_2O/Na_2O molar ratio) had a significant effect on particle sizes of the synthesized zeolites, the higher the alkalinity, the smaller the crystal particle size. In addition, it was found that crystallization temperature during hydrothermal treatment played an important role in reducing the over all reaction time. The crystallization time had effect on the crystallinity of the synthesized zeolites. Finally, the optimum synthesis parameters can be proposed in order to synthesize NaA zeolite with desirable particle size, crystallinity and morphology.