TRANSFORMACIÓN HIDROTERMAL DE PERLITA EXPANDIDA EN ZEOLITA ZSM-5. ESTUDIO DE LAS CARACTERÍSTICAS ACIDAS

CORREGIDOR, PABLO; ACOSTA, DELICIA; DESTÉFANIS, HUGO

Valparaiso

Congreso; CONAMET/SAM 2012- 12° Congreso Binacional de Metalurgia y Materiales; 2012

Universidad Técnica Federico Santa María

ZSM-5 zeolite has been prepared by hydrothermal synthesis from Expanded Perlite as the only Al source. The influence of some parameters as pH, SiO2/Al2O3 y H2O/SiO2 was studied in the preparation. ZSM-5 zeolite has been identified by X Ray Diffraction, showing that different crystallographic phases can be obtained, as Analcime, due to changes in the synthesis conditions. The generation of MFI framework is shown in the Infra-Red spectrum as the presence of an absorption band at 545 cm-1, this band is absent in Perlite´s and Analcime´s spectrum. 29Si NMR spectroscopy shows a Si/Al molar ratio of about 12 in the obtained material, and 27Al NMR confirm de incorporation of Al in the framework. The zeolite is present as well-defined coffin-shaped crystals with a BET surface area of 380 m2.g-1. The thermogravimetric analysis reveals a very good thermal stability as no fragments more than water are lost, typical for these kinds of materials. The temperature programmed desorption of pyridine and lutidine reveals a high concentration of acid sites that keeps a 70 % of them interacting with pyridine at 350 °C. Quantification of acid sites using lutidine shows that distribution of acid sites are predominantly in the microporous surface but with good distributed amount of well-accessed external acid sites.