One-pot synthesis of core-shell silica-aluminosilicate composites: Effect of pH and chitosan addition

Mesoporous silica-aluminosilicate composites have been successfully synthesized via a sol-gel process under acidic (pH 6.5) and basic (pH 11.5) conditions using cetyl trimethylammonium bromide (CTAB) as a template and chitosan as a domain size controller. The synthesized products were characterized by using Fourier Transform Infrared (FTIR) Spectroscopy, solid state Al-27 CP/MAS NMR Spectroscopy, small angle X-ray Diffraction Spectroscopy (SAXS), nitrogen sorption measurement and Transmission Electron Microscopy (TEM). Through one-pot synthesis, the uniform infiltration of mesoporous aluminosilicate in mesoporous silica was formed under strong basic conditions (pH 11.5), while self-assembled core-shell silica-aluminosilicate composites having an ordered mesoporous silica core and mesoporous aluminosilicate shell were achieved under mild acidic conditions (pH 6.5). Moreover, mesoporous silica-aluminosilicate composites of more uniform, smaller domain size and higher macroporosity were obtained when chitosan was applied. (C) 2011 Elsevier B.V. All rights reserved.