Structural, textural and toluene adsorption properties of microporous–mesoporous zeolite omega synthesized by different methods

Abstract

This work deals with the preparation of the zeolite omega using hydrothermal route. This zeolite was modified by acidic, basic and hydrothermal treatment (at 100 °C and 150 °C) using a basic/CTA+ solution. The modified zeolites were characterized by X-ray diffraction, adsorption/desorption of argon, Fourier transform infrared spectroscopy, thermogravimetric analysis TGA and scanning electronic microscopy. The obtained materials were tested for the adsorption of toluene at ambient temperature. The results showed that the zeolites modified by basic treatment showed the highest mesoporosity (~ 166 A) and the low specific surface area and pore volume, while the one treated with an acid (dealuminated) showed a mesoporosity of ~ 30 A and a higher specific surface area and porous volume. The hydrophilic character was improved after the different treatments compared to the parent material, in which the dealuminated zeolite showed the highest hydrophilic character. All modified zeolites showed a good affinity via the adsorption of toluene, and the best adsorption capacity was obtained by dealuminated zeolite. Compared to the unmodified zeolite omega (parent sample), an improvement of 68% of adsorption capacity was obtained. Finally, the dealuminated zeolite showed good stability during reuse for five cycles without loss of its adsorption capacity.