Silica-magnesia mixed oxides prepared by a modified Stober route: Structural and textural aspects

Silica-magnesia mixed oxides were prepared from tetra ethoxysilane (TEOS) and magnesium chloride (MgCl2) via a modified Stober route. The TEOS/MgCl2 molar ratio and the MgCl2 addition time were varied from 1:0 to 0:1 and 0 to I h, respectively. The materials were characterized by a set of complementary techniques, namely, Fourier Transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), X-ray diffraction (XRD), nitrogen adsorption, scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) and atomic force microscopy (AFM). Magnesium content in the silica-magnesia mixed oxides was between 3.1 and 28.6%. Increasing TEOS/MgCl2 resulted in higher crystallinity. The presence of Mg in the oxides increased specific surface area compared to the bare silica. Spherical grain morphology was observed for mixed oxide prepared with MgCl2 added after approximately 1 h of silica precipitation. (C) 2009 Elsevier B.V. All rights reserved.