THE RATE OF NUCLEI FORMATION OF ZSM-5 ZEOLITE

The crystallization processes of ZSM-5 zeolite from mixture of colloid silica, sodium aluminate, sodium hydroxide and tetrapropyl ammonium bromide at 150-195-degrees-C were studied. As the temperature increases, crystallization time decreases, crystal size becomes smaller, and the distribution becomes narrower. The rate of nuclei formation is deduced from the size distribution of final product under the assumption that crystal is growing at constant rate from the nuclei formed during the induction period. The rate of nuclei formation is also accelerated with temperature increase. When the rate constants of the crystal growth are 0.012-0.170 mum . min- 1 at 150-195-degrees-C, the crystallization curves can be simulated with the rate equation of nuclei formation deduced from the crystal size distribution of the final product.