The effects of (Na + K)/Na molar ratio and kinetic studies on the rapid crystallization of a large pored titanium silicate, ETS-10 using cost efficient titanium oxysulfate, TiOSO4 under stirring

A large pored variety of titanium silicate, ETS-10 was synthesized to investigate the effects of (Na + K)/Na molar ratio on the crystallization and phase purity using cost efficient titanium oxysulfate as the titanium source under stirring at 200 rpm and to calculate activation energy. The results showed that the (Na + K)/Na molar ratio significantly affects the crystallization and phase purity. In addition, regardless of silica and titanium sources, the morphology of ETS-10 synthesized under stirred condition is quite different from that synthesized under static condition showing a small spherical shape, and seems to be significantly affected by stirring. The composition with the shortest reaction time to reach the 100% crystallinity and purity for different silica and titanium source was chosen and applied to the kinetic study. All the experiments for kinetic study were carried out at 433, 453 and 473 K, respectively. The activation energies for three different stages, nucleation, transition and crystallization were calculated using the modified Avrami–Erofeev equation. The results of kinetic study also suggest that the effect of titanium source is more significant than that of silica source. As a comparison, the temperature dependency for titanium oxysulfate is less sensitive than for titanium sulfate except the lowest temperature (i.e., 433 K) studied in this study, suggesting that minimum temperature should be maintained to proceed the crystallization at reasonable rate for titanium oxysulfate. The modified Avrami–Erofeev equation to three different stages, nucleation, transition and crystallization for rapid crystallization seems to be excellent tool to predict the crystallization of ETS-10.