ANALYSIS OF ZEOLITE CRYSTALLIZATIONS USING AVRAMI TRANSFORMATION-METHODS

Avrami transformation kinetics have been used in the past to describe zeolite crystallization results from batch synthesis systems. It is demonstrated that the kinetic equations used to date represent only the early part of the crystallization process, i.e., the time during which nucleation is still occurring. The treatment of the growth stage of the zeolite crystallization experiment with the early-time expressions is not correct, nor is it necessary with today's computing tools. The results shown demonstrate that, for the nucleation and growth parameter values that might be expected to apply to zeolite crystallizations, the second stage of the process is by far the most important part; i.e., the growth period of the crystallization, described by kinetic equations that have been neglected to date, are important over the majority of the process, both in a time and a reactant conversion sense. Lastly, these results will demonstrate that the nucleation and growth stages of the transformation process can almost be separated completely, at least for the case of an Avrami-type transformation process.