Preparation and characterization of nanosized silicalite-2 zeolites by steam-assisted dry gel conversion method

Nanosized silicalite-2 zeolite was successfully synthesized by steam-assisted dry-gel conversion technique with TBAOH (tetrabutylammonium hydroxide) as structure directing agent and TEOS (tetraethoxysilane) as silica source. The products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, N-2 adsorption and desorption (BET) and Field emission scanning electron microscopy (FESEM). XRD pattern confirmed the crystallization of silicalite-2 obtained at 170 degrees C for 48 h, the diffraction lines of samples were broadened as a result of the decreased in particle size with the content of TBAOH increased. FESEM images showed that the silicalite-2 nanocrystals with a particle size of about 70-90 nm. N-2 adsorption and desorption provides manifest evidence that the porosity is fully accessible from the external surface of the zeolite crystal. The vibration bands at around 551.5 and 1229.2 cm(-1) indicated the presence of double 5-ring in the pentasil zeolite structure of MEL, values of the 550 cm(-1)/460 cm(-1) band intensity ratios demonstrated that the crystallinity of zeolite closed to 100%. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.