Controlling size and yield of zeolite Y nanocrystals using tetramethylammonium bromide

In this study, we developed an alternative synthesis technique for the production of small colloidal zeolite Y nanocrystals. By adding tetramethylammonium bromide as a second source of organic template, we were able to decouple and investigate the effect of two important synthesis parameters, tetramethylammonium concentration and anion concentration. Optimizing these two parameters allowed us to hydrothermally synthesize highly crystalline zeolite Y in a disperse nanocrystal form with a controllable particle size of 32-120 nm. Crystals hydrothermally synthesized with a 1.00Al(2)O(3)-4.35SiO(2)-2.40(TMA)(2)O(2OH(-))-1.2(TMA)(2)O(2Br(-))-0.048Na(2)O-249.00H(2)O (T3.6) solution composition were 45% smaller by volume after 54 h of crystallization at 100 degreesC and were obtained with 73% more yield (g zeolitic Al2O3+SiO2/g synthesis Al2O3+SiO2) than crystals synthesized with a 1.00Al(2)O(3)-4.35SiO(2)-2.40(TMA)(2)O(2OH-)-0.048Na(2)O-249.00H(2)O (T2.4) composition. After 216 h, T3.6 syntheses contained 37 mn crystals with 180% higher yield than that of T2.4 syntheses at 54 It (38 nm crystals, 0.044 g zeolitic Al2O3+SiO2/g synthesis Al2O3+SiO2)The mechanisms involved in the observed crystal size decrease and yield improvement are discussed. A detailed characterization of our zeolite Y nanocrystals is given, including powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), N-2 adsorption, dynamic light scattering (DLS), transmission electron microscopy (TEM), thermogravimetric (TG) analyses Si-29 magic angle spinning nuclear magnetic resonance (Si-29 MAS NMR) and inductively coupled plasma optical emission spectrophotometry (ICP OES) elemental analyses. (C) 2003 Elsevier Science Inc. All rights reserved.