Capillary hydrodynamic fractionation studies on the crystal growth of TS-1 zeolite

Capillary hydrodynamic fractionation (CHDF) was used, for the first time, to gain information about the particle growth mechanism of TS-1 zeolite. The particle size and the particle size distribution (PSD) of the mother solution were directly and easily monitored by CHDF during crystallization. The effects of the reaction temperature, and the ratios of H₂O/Si and TPAOH/Si on the particle growth were studied. During crystallization of zeolite particles, bimodal PSD and an abrupt increase in the number average particle size (30 to 60-80 nm) were observed. It is suggested that zeolite particles of 60-80 nm formed by the aggregation of several particles of 30 nm (i.e. particle intergrowth mechanism). The apparent activation energy for particle intergrowth was 30 kJ/mol. The maximum intergrowth time decreased with increasing reaction temperature, whereas it increased with increasing H₂O/Si ratio. The proposed particle growth mechanism was also compared with SEM and TEM results.