Abstract
Pseudomorphic transformation is a promising alternative to conventional approaches for the preparation of binderless preshaped zeolite beads. However this method was until now restricted to zeolites synthesized in low alkaline media (OH-/SiO2 << 1) (ZSM-5, FER, BEA), where the silica dissolution rate was slow in comparison to zeolite crystallization rate. In this study, we demonstrated the possibility to prepare binderless zeolite aggregates beads of SOD, LTA and FAU-X requiring usually high alkaline media (OH-/SiO2 > 2). This was achieved by adding the right excess of aluminum to amorphous silica beads of the desired size and shape. Zeolite aggregate beads of SOD, LTA, FAU-X of 10,70 mu m and 1 mm were obtained in a one-step synthesis process with high synthesis yields. These zeolite beads are formed by an aggregation of small crystals of 1.5 mu m. The preservation of the adsorption properties of these zeolite pseudomorphs were highlighted by N-2 sorption at -196 degrees C and QE-TPDA of n-hexane experiments at room temperature. These zeolite beads would be highly suitable for column filling and continuous flow applications as catalysis or adsorption. (c) 2013 Elsevier Inc. All rights reserved.