Syntheses from Kaolin and Crystallization Kinetics of Binder-Free High-Silica Zeolite NaY

Abstract

A set of studies have made it possible to develop a method for the synthesis of high-silica zeolite NaY-FS, which has a high adsorption capacity and a developed secondary porous structure. The method involves mixing kaolin with powdered zeolite NaY, polyvinyl alcohol (PVA), and fumed silica (FS) in an amount to have the total content of components in the mixture as follows (wt %): zeolite NaY (molar ratio SiO₂/Al₂O₃ = 5.5–7.0) 55–70, PVA 1–2, fume silica 3‒7, and kaolin the rest; moistening and stirring the mixture until a homogeneous mass, shaping granules; their calcining; hydrothermal crystallization in a sodium silicate solution from reaction mixtures with the composition (2.4‒3.6) Na₂O ⋅ Al₂O₃ ⋅ (10‒12) SiO₂ ⋅ (180‒220) H₂O; and washing and drying the granules. In addition, the crystallization kinetics of zeolite NaY-FS from the reaction mixtures of these compositions has been studied.