Catalytic Activity of Mesoporous SBA-15 modified with Pt and Ti in a Deep Methane, n-hexane and CO Oxidation

Ti-SBA-15 composite materials containing 5 and 10% Ti are obtained by direct synthesis (samples denoted Pt Tix) or by impregnation of SBA-15 with titanium isoporopoxide solution (samples denoted i-Tix, x is Ti concentration). After calcination, the composite Ti-SBA-15 oxides are impregnated with an aqueous solution of a Pt precursor. The as-synthesized samples are characterized by SEM, XRD, XPS and tested in reaction of CO oxidation, n-hexane and methane combustion. XPS results reveal the presence of Pt+ and Pt0 on the surface of oxidized Pt Tix sample and strong interaction between Pt0 and Ti in i-Tix sample. After deposition of Pt on this sample, the finely dispersed Pt metal and Pt2O are formed on the support. The modification of pure siliceous SBA-15 with titanium by impregnation results in the formation of finely divided TiO2. Successive introduction of platinum leads to the formation only of Pt0 with 40 nm particles. The catalysts in which Pt is in a form of large metal particles and TiO2 is finely dispersed on the support exhibit highest catalytic activity in all studied reactions. The presence of water caused an increase in catalytic activity in CO oxidation and this is more remarkable for impregnated samples.