Crystallization Field and Rate Study for the Synthesis of Ferrierite

Abstract

A partial crystallization field and rate study was performed for the synthesis of ferrierite from gels of variable composition: 1.85Na2O·Al2O3·xSiO2·592H2O·19.7R, where R = pyrrolidine or ethylenediamine. The variables of syntheses were the SiO2/Al2O3 molar ratio of the gel (10 < x < 25), temperature (150 °C < T < 225 °C), and crystallization time (t < 480 h). The crystallization rate was determined to be strongly dependent on temperature, whereas the SiO2/Al2O3 ratio and template type had no significant influence. Ferrierite was the only crystalline phase observed throughout the entire crystallization field studied when ethylenediamine was the templating agent. For some batches, mordenite appeared as a crystalline impurity when pyrrolidine was the template. Thermal stability tests indicated that ferrierites retained their crystallinities up to 1050 °C. The methanol sorption capacity of highly crystalline ferrierite samples approached the theoretical sorption volume, indicating that it can be used as a measure of purity for single-phase ferrierite samples.