Synthesis of NaX zeolite at room temperature and its characterization

•NaX zeolites obtained at different crystallization times at room temperature were investigated.•Although the 28 days product was fully crystalline, the crystals continued to grow.•NaX zeolites were composed of many closely packed nanocrystals with the average size of around 30 nm.•Long crystallization time favored the aggregation of individual nanocrystals.

NaX zeolites were prepared by the hydrothermal method at room temperature and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), particle size analysis and N2 adsorption–desorption techniques. The results indicated that although the 28 days product was fully crystalline according to the XRD investigation, the crystals continued to grow. TEM images revealed that the products were composed of many closely packed nanocrystals with the average size of around 30 nm. Long crystallization time favored the aggregation of individual nanocrystals, which led to the formation of larger congregated agglomerates. Moreover, no peak of NaA zeolite was detected during the crystallization process.

Graphical abstractTEM micrographs revealed that the NaX zeolites were composed of many closely packed nanocrystals with the average size of around 30 nm. Furthermore, long crystallization time favored the aggregation of individual nanocrystals, which led to the formation of large congregated agglomerates.Figure optionsDownload full-size imageDownload as PowerPoint slide