Synthesis and characterization of nanocrystallite aluminium-rich beta zeolite

The aluminium-rich beta zeolite with relatively high crystallinity and nanometer size was synthesized in the neutral system, in which the lower water content and F^- anion were involved. The solid aluminosilicate gel was prepared as the original materials. The effects of synthesis conditions and the calcined aluminosilicate gel properties on the crystallization products were investigated. The evolvement of Al coordination situation had also been studied during crystallization process. The crystallization products were determined by means of XRD, XRF, SEM, TEM, ²⁷Al MAS NMR methods. The results showed that the crystallization conditions involved F^- anion and H₂O/SiO₂ mol ratio 2.4~6.0 as well as solid aluminosilicate gel calcined at high temperature contributed to aluminium-rich beta zeolite with relative higher crystallinity and nanometer size. The solid aluminosilicate gel was calcined to lead to production of four-coordinated aluminium subjected to being transformed into beta zeolite framework. The part of six-coordinated aluminium slowly dissolved into the crystal nuclei during crystallization period. The result led to get the nanometer aluminium-rich beta zeolite at last.