Kinetic study of the crystallization of ZSM-5 under organic template-free conditions

Here, the ZSM-5 zeolite was prepared under organic template-free conditions at different reaction temperatures and initial gel compositions using a hydrothermal process. A kinetic study of the synthesis of Zeolite was performed based on crystal growth. The crystallinity degree of the prepared samples was calculated from the PXRD and FT-IR results and then the crystallization curves were obtained. From these curves, the kinetic parameters were computed. The obtained results showed that by increasing the Na+ content of the initial gel composition, the activation energy for the crystal growth was reduced and as a result, the crystallization rate of ZSM-5 zeolite was enhanced due to the structure-directing role of Na+ cation. The activation energy of the induction step, transition step and crystal growth step are 122.8, 46.2, and 48.5 kJ/mol respectively for the molar ratios of 29Na(2)O:63SiO(2):Al2O3:2400H(2)O:16H(2)SO(4) and 141.0, 70.4, and 80.8 kJ/mol respectively for the molar ratios of 16Na(2)O:31SiO(2):Al2O3:2400H(2)O:16H(2)SO(4).

Automated summary

In this study, ZSM-5 zeolite was prepared without organic templates using a hydrothermal process, and the synthesis kinetics were investigated based on crystal growth. The results showed that increasing the Na+ content in the initial gel composition decreased the activation energy for crystal growth and enhanced the crystallization rate of ZSM-5 zeolite.