Obtenção de zeólita mesoporosa por síntese direta

Abstract

Mesoporous zeolite samples were obtaining through direct synthesis by using mesoporous carbon molecular sieve CMK-3, activated charcoal and carbon black as templates for mesoporosity. In order to evaluate the effect of these templates, samples of zeolite presenting SiO2/Al2O3 molar ratios equal to 25, 60 and 90 were prepared following procedures described in the literature and adding different amounts of these templates to the synthesis gel. The zeolite samples obtained were characterized by X-ray diffraction (XRD), by X-ray fluorescence (XRF), by N2 adsorption/desorption, by temperature programmed desorption of ammonia (NH3-TPD) and by scanning electron microscopy (SEM). An evaluation of some samples was carried out using the n-heptane cracking reaction at 350°C.For the zeolite samples having SiO2/Al2O3 molar ratio equal to 25 and 60 was observed a slight increase of the mesopore volume as the amount the activated charcoal was increased. All samples presented similar catalytic activity and selectivity, forming mainly C3 and C4 hydrocarbons in the n-heptane cracking reaction.