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 of crystal growth, nucleation, and overall crystallization of zeolite A was studied by different experimental methods such as X-ray diffractometry, scanning-electron microscopy, measurement of the size of the largest crystals during the crystallization, particle size analysis of the crystalline end products, and the measurement of silicon and aluminum concentrations in the liquid phase. Experimental results were analyzed and discussed in terms of the distribution of nuclei in the gel matrix and the influence of the distribution of nuclei on the rate of nucleation and overall crystallization, respectively. The influence of the variation in the number of nuclei and crystal growth rate on the rates of nucleation and crystallization was considered. (C) Elsevier Science Inc. 1997.