Hydrothermal synthesis of zeolites from natural stellerite

Y and P zeolites were synthesized hydrothermally from natural stellerite under different conditions and were characterized via XRD and FT-IR.The results show that the higher crystallinity of Y zeolite can be obtained in hydrothermal system with low alkalinity,low Ca2+/Na+ ratio,and high SiO2/Al2O3 ratio.The lattice space of the samples decreases as crystallization time increases.P Zeolite is prompted under condition of higher alkalinity and higher Ca2+/Na+ ratio.The intensity and number of bands in the range of 400 cm-1～900 cm-1 increases with reaction time.Bands at 680 cm-1,760 cm-1 and 860 cm-1 corresponding to Y zeolite appear during the crystallization stage.Most of these bands shift to higher wavenumbers when SiO2/Al2O3 ratio increases generally.In the hydrothermal system with reverse condition above,bands at 600 cm-1,420 cm-1～470 cm-1 hardly change as the crystallization time increases and the main crystal phase of P zeolite is obtained.