Synthesis and characteristics of ZSM-5 zeolite prepared from water glass

ZSM-5 was synthesized from water glass as the silica source and Al(OH) ₃ as Al source. Water glass is an inexpensive silica source, but controlling the reactant composition was difficult because of the high alkali content in water glass. Considering environmental and economic concerns, we propose a new alkali extraction method using methanol to remove the alkali ingredients from water glass. When the MeOH/SiO ₂ molar ratio was 3, the maximum extraction of alkali components occurred. After extracting with MeOH, the filtrates were analyzed by UV spectroscopy and titration methods, and we determined the Al ₂O ₃:SiO ₂:Na ₂O: H ₂O molar ratio to be 1:58:7.55:1510. Crystallization by hydrothermal synthesis was performed at various reaction temperatures and times. Characterizations were carried out by means of XRD and SEM. ZSM-5 display a characteristic MFI peak in its XRD pattern and its crystals have planar shapes and 1~2 μm particle sizes. Alkali extraction using methanol in a template-free system is a better method for controling the level of Na ₂O in water glass used for ZSM-5 synthesis.