INFLUENCE OF SYNTHESIS PARAMETERS IN THE PROPERTIES OF MCM-22 ZEOLITE / INFLUÊNCIA DOS PARÂMETROS DE SÍNTESE NAS PROPRIEDADES DA ZEÓLITA MCM-22

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

MCM-22 zeolite was first synthesized by Mobil researchers in 1990. It is an aluminosilicate with molecular sieve characteristics and several applications in catalytic processes because of its two independent pore systems. In this work, the MCM-22 zeolite synthesis conditions were studied using both static as stirred hydrothermal treatment. Molar composition of synthesis gel was fixed while the temperature and the gel aging time were varied. The products obtained were characterized using analytical techniques of X-ray diffraction with Rietveld refining, nitrogen adsorption (BET), infrared spectroscopy, atomic emission spectrometry, nuclear magnetic ressonance spectroscopy (NMR), scanning electronic microscopy (SEM) and transmission electronic microscopy (TEM). Typical MCM-22 zeolite was only obtained from hydrothermal treatment in stirring conditions. Samples obtained by static conditions showed contamination with ferrierita and ZSM-5 zeolites and quartz. The morphology of the samples, as showed by scanning electron micrographs, changed according the conditions of hydrothermal treatment, static or stirring. These differences affected the BET surface areas of obtained samples. However, no differences were observed in pore volume in samples obtained by static system, except the sample synthesized in 5 days, which presented an amorphous phase. Although, there were contaminant phases, transmission electron micrographs permitted to observe the crystal growing in the three directions. Trough infrared spectra it could be observed the template elimination and the zeolite hydrophilic nature after process calcination.

ASSUNTO(S)

characterization synthesis sintese mcm-22 caracterizacao zeolite zeolita mcm-22

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