Determination of physical parameters applicable for scale-up of NaA zeolite synthesis from aluminosilicate gels

Abstract

It was studied the effect of physical parameters that influence NaA zeolite preparation, in order to determine favorable conditions for scaling this synthesis. The study was done from a mixture of fixed composition and crystallization at 80°C. Physical parameters such as, order and speed of adding the initial solutions, speed and stirring time of the synthesis mixture, stirring during crystallization, crystallization time and recycling of mother liquor separated during the filtration, were studied. The samples were identified by X-ray diffraction (XRD), characterized by scanning electron microscopy (SEM) and water adsorption capacity was determined. The best preparation conditions found were the rapid and simultaneous addition of initial solutions, because it originates a lower preparation time of the synthesis mixture. The stirring during crystallization produces a reduction of heating time into the mixture, and an increase of crystallization rate. A zeolite with high crystallinity and purity can be obtained in 1 hour. Also, it was proved the feasibility of using mother liquor as alkali solution for the synthesis, representing a saving of reagents.