INFLUENCE OF GEL PROPERTIES ON THE CRYSTALLIZATION OF ZEOLITES .1. INFLUENCE OF ALKALINITY DURING GEL PREPARATION ON THE KINETICS OF NUCLEATION OF ZEOLITE-A

The influence of alkalinity during gel precipitation on the kinetics o f crystal growth, nucleation, and overall crystallization of zeolite A was studied by different experimental methods such as X-ray diffracto metry, scanning-electron microscopy, measurement of the size of the la rgest crystals during the crystallization, particle size analysis of t he crystalline end products, and the measurement of silicon and alumin um concentrations in the liquid phase. Experimental results were analy zed and discussed in terms of the distribution of nuclei in the gel ma trix and the influence of the distribution of nuclei on the rate of nu cleation and overall crystallization, respectively. The influence of t he variation in the number of nuclei and crystal growth rate on the ra tes of nucleation and crystallization was considered. (C) Elsevier Sci ence Inc. 1997.