Morphology-Controlled Synthesis of Zeolite and Physicochemical Properties

Abstract

Zeolite L is a crystalline aluminosilicate compound and a typical chemical composition of K₉Al₉Si₂₇O_72•nH₂O (n = 0 - 36). The structure and chemical properties, as well as their sizes and morphologies of zeolite L has led to various applications in different fields. The aim of this study is to investigate the effects of chemical compositions of the starting gel on the synthesis, size and morphology of zeolite L crystals. Zeolite L had been synthesized hydrothermally at 180^oC for 2 days, from gels with the molar compositions of 2.62-3.78 K₂O: 0.8-1.4 Al₂O₃: 8-12 SiO₂: 80-200 H₂O. The variation of chemical compositions led to the differences in morphologies and crystal sizes. Their morphologies varied from ice hockey to cylindrical shapes and their crystal sizes varying from 1.50-7.53 µm. With an increase in H₂O and SiO₂, the crystal size was also increased but decreased with an increase in K₂O. In varying Al₂O₃, there was no effect on their shapes which were still cylindrical but with different crystal sizes. Moreover, the adsorption of ethylene on zeolite L samples depended significantly on crystal shapes and sizes.