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

Silica-magnesia mixed oxides were prepared from tetraethoxysilane (TEOS) and magnesium chloride (MgCl2) via a modified Stöber route. The TEOS/MgCl2 molar ratio and the MgCl2 addition time were varied from 1:0 to 0:1 and 0 to 1 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.

Silica-magnesia mixed oxides were prepared from TEOS and magnesium MgCl2 via a modified Stöber route. Increasing TEOS/MgCl2 ratio affords higher crystallinity. The presence of Mg in the oxides increases specific surface area compared to bare silica. Spherical grain morphology was observed for mixed oxide prepared with MgCl2 added after approximately 1 h.Figure optionsDownload as PowerPoint slide