Influence of silica precursors on octahedron shaped nano NaY zeolite crystal synthesis

• Synthesis of octahedron shaped, smooth faces and sharp edges NaY zeolite crystals.
• Use of tetraethyl orthosilicate as silica source produces high purity NaY zeolite.
• NaY zeolite crystals of size around 50 nm can be synthesized.
• Prolonged thermal treatment of NaY zeolite crystals also affects its phase purity.

The present work reports the synthesis of nanosized NaY zeolite crystals from clear solution using different silica sources, i.e., tetramethylammonium silicate (TMAS), colloidal silica suspension (CSS) and tetraethylorthosilicate (TEOS). The examination of phase purity by X-ray diffraction (XRD), morphological studies by scanning electron microscopy (SEM), and evaluation of particle nature and colloidal entities by light scattering analysis (LSA) reveals that the use of different silica sources significantly influenced the properties of final product. The NaY zeolite crystals obtained from TEOS have high phase purity and narrow particle size distribution. SEM and LSA results reveal that the use of TEOS as silica source produces NaY zeolite crystals of average size of 85 nm whereas TMAS yields particle of size around 50 nm but in aggregated form. Furthermore, the prolonged hydrothermal treatment in case of TMAS containing precursor solutions leads to the phase transformation NaY to NaA zeolite by aggregation growth process.

The silica source undoubtedly influences the properties of NaY zeolite crystals. TEOS gives pure NaY zeolite phase but TMAS and CSS give NaA zeolite as crystalline impurity although it was very low in volume in comparison to NaY.Figure optionsDownload as PowerPoint slide