Surface functionalization of SBA-15-ordered mesoporous silicas:Oxidation of benzene to phenol by nitrous oxide

摘要

We report the preparation and catalytic properties of highly ordered mesoporous Fe-Ga-SBA-15 materials via direct hydrothermal synthesis.Gallium and iron ions were introduced directly into the synthesis gel typical for the preparation of SBA-15.The resulting materials had hexagonally ordered mesopores of about 6 nm and surface areas >1000 m2/g.In Fe-SBA-15,the iron species were mainly tetrahedrally coordinated in the amorphous silica walls.In the presence of Ga (Fe-Ga-SBA-15),Fe species were located at the silica surface as isolated species,as determined by Raman and diffuse-reflectance UV-Vis spectroscopy measurements.The Fe species in Fe-Ga-SBA-15 displayed similar properties as the FeZSM-5 zeolites toward nitrous oxide decomposition and were active in the oxidation of benzene to phenol by nitrous oxide.Ga-SBA-15 and Fe-SBA-15,on the other hand,showed no catalytic activity.Compared with Fe-Al-SBA-15,Fe-Ga-SBA-15 displayed greater selectivity to the desired phenol product.