Synthesis of hierarchical zeolite T nanocrystals with the assistance of zeolite seed solution

Abstract

Hierarchical zeolite T aggregates with the size range of 200–400 ​nm were successfully synthesized by zeolite seed solution-assisted method. The addition of zeolite seed solution can provide active precursors such as secondary building units and organic template to promote crystallization rate and enhance the purity and crystallinity. Compared to zeolite T samples synthesized under the similar synthesis conditions in the previous literatures, zeolite crystals obtained in the presence of zeolite seed solution have 1/10–1/5 crystal size and 1/5–1/2 synthesis time. The synthesized samples typically display the elliptic-like zeolite T aggregates composed of tightly packed nanosized fiber-like shaped crystals, resulting in the additional intercrystalline mesopores of samples between these nanocrystals. Crystal growth of zeolite samples synthesized using zeolite seed solution was investigated at 353–393 ​K. Both of nucleation and crystal growth rate increase when the crystallization temperature increase from 353 ​K to 393 ​K, and the nucleation is rate-limiting step since the value of nucleation rate is less than that of crystal growth rate at each temperature. Moreover, the magnitudes of nucleation and crystal growth activation energies obtained from crystallization data are 35.0 and 28.9 ​kJ ​mol−1, respectively, implying that crystal growth process is controlled by surface kinetics.