Mesoporous Silica SBA-15 Supported Co3O4 Nanorods as Efficient Liquid Phase Oxidative Catalysts

Mesoporous silica SBA-15 supported cobalt oxide composites prepared via the double-solvent, impregnation and adsorption techniques were characterized by diffuse reflectance UV-Vis (DR UV-Vis), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The potential of these cobalt modified composites to oxidize norbornene, benzyl alcohol and 1-phenylethanol was determined by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). SEM images indicated that, irrespective of cobalt content (Co-content), the integrity of the mesoporous channels remained intact for all methods. DR UV-Vis exhibited a red-shift which increased with Co-content for catalysts prepared by the double-solvent technique and is attributed to more extensive crystal growth. The morphology of the cobalt oxide species had a direct impact on the pore volume (Pv) and surface area (SA) of the composites and this, in turn affected the catalytic activity. For catalysts prepared by the double-solvent technique, the activity was in reverse proportion to the Co-content. This is attributed to reduced Pv which limits the active SA available.