Síntese, caracterizações e aplicações de zeólitas: uma revisão bibliográfica

Abstract

Zeolites are structures composed of the chain of TO4 units, where T is an atom of silicon (Si+4) or aluminum (Al+3), coordinated by four oxygen atoms organized in a three-dimensional tetrahedral network. The discovery of the natural mineral took place in 1756 and, until the mid-1930s, the description of some specificities of zeolitic materials, such as their ability to carry out ion exchange and adsorption, as well as their behavior as a molecular sieve and some structural properties, had already been described in the literature. From these studies, between the 1930s and 1940s, the synthesis of zeolites and more in-depth research on their structures and applications were developed, thus enabling the introduction of this material in the industry. There are numerous types of natural and synthetic zeolites and they can have different structures and dimensions, being classified according to their secondary construction units, the diameter of their pores, the number of Si or Al atoms present in the openings of the larger micropores or the Si/Al ratio present in its structure. Among the various types of zeolites, there are faujasites, which can be of type X and Y (faujasite), being structurally identical, differing only in the Si/Al ratio. While zeolite X has a Si/Al ratio between 1 and 1.5, the ratio of zeolite Y is greater than 2.5. New studies are being developed using mineral rocks, clays and industrial residues in the synthesis of zeolites, due to the availability of the raw material and the even greater reduction in its cost. This work will propose to present the historical development of Faujasite zeolites, from the discovery of this mineral to the present day, the main synthesis methods, the characterizations through the analysis of their morphology through scanning electron microscopy (SEM-EDS), their groups functionals by the Fourier Transform Infrared Spectroscopy (FTIR) technique and their crystalline structure by the X-Ray Diffraction (XRD) technique. In addition to demonstrating, from the applications of zeolitic materials in catalysis, adsorption and ion exchange, the importance of continuous study and research in this area.