Abstract

ROBLEDO MUNIZ, J. G. et al. Synthesis and characterization of high silica zeolites from coal fly ash(CFA): two cases of zeolite syntheses from the same waste material. Lat. Am. appl. res. [online]. 2010, vol.40, n.4, pp.323-328.. ISSN 0327-0793.

Zeolites H/β and H/ZSM-11 were synthesized by the crystallization hydrothermal method (CH), using coal fly ash (CFA). Tetraethylammonium hydroxide (TEAOH), tetrapropylammonium bromide (TPAB) and tetrapropylammonium hydroxide (TPAOH) were used as structure-directing agents (SDA). The optimum conditions used in the experimentation were 140 °C and NaOH/CFA ratio=1.2 (wt/wt), during the crystallization hydrothermal method (CH), and microwave-assisted heating (MH) was used in some experiments. The structure and crystallinity of the synthesized materials were analyzed by X-ray diffraction, where the formation of the β and ZSM-11 zeolites was confirmed. The morphology of the obtained zeolites was observed by the scanning electron microscope technique. It was observed spheroidal particles for the ZSM-11 zeolite and ellipsoidal particles for the β zeolite, respectively. Both zeolites were ion exchange treated, in order to obtain the protonated form. Finally, the thermal stability and the loss of weight of the modified β zeolite were determined by using the termogravimetric and differential thermal analysis techniques. The modified zeolites were stable in the range of most gas chemical reactions (300-500 °C).

Keywords : Zeolite H/β; Zeolite H/ZSM-11; Crystallization Hydrothermal Method; Coal Fly Ash. Structure-Directing Agents.

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