In Situ UV Raman Spectroscopic Studies on the Synthesis Mechanism of Zeolite X

    Published Online: Apr 21 2008

AbstractThe hydrothermal synthesis of Zeolite X was studied by in situ UV Raman spectroscopy for the first time. An in situ Raman cell was specially fabricated for investigating the species derived in both solid and liquid phase under high pressure at temperatures up to 250 . Under hydrothermal synthesis condition, it was observed that the liquid phase is dominated by monomer silicate species, which are loosely bonded to the gel phase and involve in zeolite framework formation, and amorphous aluminosilicate species composed of predominately four-membered rings are formed in the solid phase in the early stage of nucleation. The characteristic Raman bands of four-membered rings species were also calculated with DFT. It is proposed that four-membered rings formed at initial nucleation interconnect with each other via six-membered rings to form the zeolite X framework.

Keywordshydrothermal synthesis • Raman spectroscopy • reaction mechanisms • UV spectroscopy • zeolites