Synthesis of nanocrystalline nitrate enclathrated zeolite with intermediate framework structure between sodalite (SOD) and cancrinite (CAN)

Nanocrystalline NaNO3 enclathrated microporous material with intermediate structure (INT) between the well known zeolites sodalite (SOD) and cancrinite (CAN) can be prepared from aluminosilicate gels under addition of high amounts of NaOH and NaNO3 using low temperature conditions (333 K) within reaction periods of 1 96 h. The nanocrystalline products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and simultaneous thermal analysis (STA). Crystal sizes around 50 nm were found within the products. The nanocrystallites were compared with microcrystalline nitrate cancrinite synthesized under the well known conditions of hydrothermal transformation of kaolinite in NaOH at 473 K for 48 h. In further experiments triethanolamine (TEA) was added to the starting batch to study the influence on nanocrystalline phase formation in superalkaline salt bearing gels under the low temperature conditions at 333 K. A strong effect of TEA was found persisting in a remarkable influence on the morphology of the nanoparticles. In the TEA system INT always crystallized as big spheres each one consisting of countless nanocrystalline rods of about 40 nm diameter and about 250 nm in length.