J. Phys. Chem. B 2005, 109, 4485-4491
4485
Ordered Micro/Mesoporous Composite Prepared as Thin Films N. Petkov,† M. Ho1 lzl,† T. H. Metzger,‡ S. Mintova,*,† and T. Bein† Department of Chemistry, LMU, Butenandtstr. 11, 81377 Munich, Germany, and ESRF, Grenoble, France ReceiVed: December 3, 2004; In Final Form: January 11, 2005
A new synthesis method for preparation of thin films and powders consisting of zeolite beta nanocrystals embedded in ordered mesoporous silica matrix is described. The final structures possessing bimodal porosity, i.e., high degree of mesophase order and spatially defined microporous zeolite nanocrystals are obtained via simultaneous solvent evaporation of preformed silica/surfactant/ethanol/nanosized zeolite beta assemblies. The films were characterized with grazing-incident diffraction (GID), nitrogen sorption based on gravimetric measurements with quartz crystal microbalance (QCM) devices, and transmission electron microscopy (TEM). It is shown that the incorporation of beta nanocrystals in the mesoporous silica matrix and the mesophase order itself can be controlled through the variation of the fractional amounts of the zeolite nanoparticles and silica/surfactant solutions. The HR-TEM measurements showed that the nanosized Beta microporous crystals are separated and at the same time connected through an ordered mesostructured matrix.
Introduction Zeolites and zeolite-like materials with their uniform pore sizes, unique structural topology and composition, well-defined acidity, and good thermal stability are viable commercial catalysts, selective ion exchangers, and adsorbers.1,2 However due to their limited pore sizes (
