Cristalização da zeólita ferrierita sem direcionador orgânico, variando-se a alcalinidade e o teor de sementes

Abstract

Zeolites are crystalline aluminosilicates of natural or synthetic origin, with a structure consisting of an extensive microporous three-dimensional network, routinely used as catalysts, ion exchange and adsorbents. The production of ferrierite and other zeolites are limited due to the high cost of the organic structure-directing agents used in synthesis. Many studies are conducted with the goal of finding a viable and more economical route to the possibility of industrial scale production. The purpose of this study was to obtain a methodology for synthesis of ferrierite without using organic structure-directing agents, by hydrothermal method, inserting seeds during the crystallization gel preparation and varying the alkaline concentration of the mixture in order to achieve shorter times of crystallization and lower cost production at a temperature of 200°C. For the synthesis of materials prepared in this work were used: fumed silica as silicon source, pseudoboehmite as a source of aluminum, sodium and potassium hydroxide as sodium and potassium sources, respectively. As seeds to crystallization, samples of commercial ferrierita were used. The synthesized samples were characterized by X-ray diffraction (XRD), spectroscopy of the Fourier transform infrared (FT-IR) and thermal analysis (TG/DTA). The X-ray diffraction patterns showed characteristic peaks of zeolite desired in all conditions of synthesis. The infrared spectra showed bands characteristic of ferrierite, as a further indication of the formation of zeolite. TG curves showed a mass loss of up to 10% in the temperature range from 23 to 400°C. The results of the analysis confirmed the formation of zeolite ferrierite with good crystallinity and purity, proving the efficiency of the methodology.