Síntese e caracterização dos sólidos: zeólita MCM-22 e membrana zeolítica (MCM-22/α-Alumina).

Abstract

This study aimed to develop general-type materials: zeolite MCM-22, ceramic support membranes and zeolite (MCM-22 / α-alumina). The study was conducted in three parts described as follows: In Part 1 the preparation of zeolite MCM-22 was performed following the method of hydrothermal synthesis, varying the crystallization time (8 to 10 days). Several characterizations (XRD, EDX, SEM and DTA / TG) were performed. In Part 2 the ceramic support was prepared by molding technique and subsequently subjected to sintering temperature of 1400 ° C/1h and characterized (XRD, SEM and mercury porosimetry). In Part 3 zeolite membranes (MCM-22 / α-alumina) were prepared by three methods: (a) hydrothermal synthesis, (b) secondary growth (Rubbing) and (c) mechanical mixture and characterized by XRD and SEM. The achievement of zeolite MCM-22 could be confirmed by X-ray diffraction, but the material became more crystalline with increasing time of crystallization. From the images obtained by SEM, we could analyze the zeolites are composed of clusters of particles of spherical shape. The curves of DTA / TG showed that while the MCM-22 crystallized, the amount of organic material retained in the solid increases. The results obtained for the ceramic support (α-alumina) showed that it has characteristic peaks of aluminum oxide. Through the micrographs we observed a heterogeneous microstructure with a compact, without cracks on the layers. Because the average pore diameters obtained by mercury porosimetry, the media can be classified as microfiltration. Through the method of hydrothermal synthesis was not observed that the formation of crystals of zeolite MCM-22 zeolite in the membrane, being observed only peaks characteristic of alumina in the XRD. The micrographs confirmed the results observed in XRD, where it is observed that there was no layer formation of zeolite MCM-22 on the surface of the ceramic support. According to the XRD, for the method of secondary growth (Rubbing), we can observe that the zeolite MCM-22 synthesized on the ceramic support made crystal structure. The micrograph of the zeolite membrane (MCM-22/α-alumina) showed the formation of a layer of zeolite on the ceramic support, where spherical-shaped crystals grew to the substrate. The diffractogram for mechanical mixing, showed characteristic peaks of zeolite MCM-22 and the ceramic support, confirming the formation of zeolite membrane (MCM-22/α-alumina). By scanning electron microscopy it appears that the zeolite membrane crystals with spherical shape are dispersed to support ceramic α-alumina.