Effects of Synthesis Parameters on Organic Template-Free Preparation of Zeolite Y

摘要

In this work, the effects of reaction conditions on the conventional hydrothermal synthesis and crystal growth kinetics of zeolites Y in aqueous sodium alkaline solutions without the use of organic templates were studied. For this purpose, a series of Y-type zeolites were synthesized at different reaction conditions such as various aging temperatures, crystallization temperatures, Na2O contents of the initial gel and crystallization times using hydrothermal process. The prepared samples were well characterized by the X-ray diffraction (XRD) and N-2 adsorption-desorption techniques. The results prove that the Na2O contents of the initial gel and synthesis temperature increase the rate of the Y and P zeolite crystallization. The effect of Na2O and temperature on the synthesis of two different zeolite types (Y and P) with a constant initial synthetic composition under the organic template-free synthesis of zeolite Y was studied. In inappropriate conditions, the P-type zeolite was the major impurity obtained along with the Y-type zeolite. Also from the experimental results, the kinetic parameters for both zeolite Y and zeolite P were calculated. The kinetic study show that the activation energy for crystallization of both zeolites was enhanced by increasing the Na2O content of the initial gel due to the structure-directing role of Na+ cation in the induction period and crystal growth step.