Síntese de zeólita ZSM-5 e membrana zeolítica (ZSM-5/α-alumina) através do método hidrotérmico.

Abstract

Zeolite membranes are a class of inorganic microporous membranes where zeolite crystals grow in form of a continuous film on a porous support. This work aims to synthesize and characterize ZSM-5 zeolite, synthetize zeolite membranes (ZSM-5 / α-alumina) on laboratory scale using successive hydrothermal synthesis. We have developed the following materials: zeolite ZSM-5, through the conventional method (using hydrothermal synthesis technique), the ceramic support (α -alumina) using molding technique followed by sintering, and zeolite membranes by Direct Method "in situ" and Secondary Growth Method. Results showed that: X-ray diffractogram of zeolite membrane obtained by Secondary Growth Method and the zeolite membrane diffractogram obtained after the 3rd successive synthesis by Direct Method "in situ" showed the crystallization of ZSM-5, with characteristic peaks of the MFI group structure, at the ranges 2θ = 7- 9° and 23-25°, as well as the formation of the α-alumina characteristic peaks at 25, 35, 38 and 43°. About the cross section scanning electron microscopy images (fractured) from the zeolite membranes, can be observed that the zeolite membrane obtained by secondary growth method showed three distinct regions (I, II and III) while the zeolite membrane obtained after the 3rd successive synthesis by Direct Method "in situ" showed the formation of two regions only (I and II). Based on results it was concluded that the presence of ZSM-5 specific peaks together with the α -alumina in the X-ray diffractograms confirmed the zeolite membrane structure formation obtained by both methods (Secondary Growth Method and Direct Method "in situ").