Direct oxidation of propylene with molecular oxygen over Ti-modified sulfated zirconia catalyst, 2. In situ diffuse reflectance FT-IR study

During the reaction of propylene with O-2, in situ Diffuse Reflectance FT-I R measurements were performed over Ti-modified SZ and SZ catalysts. Without O-2, the main bands characteristic of (branched) hydrocarbons, formed by o ligomerization leading to, finally, carbonaceous residue, appeared within t he range of 3900-2750 cm(-1), which was affected by the bands of surface OH groups. Investigation of these IR bands showed the role of molecular oxyge n not only to limit the formation of carbonaceous species on the catalyst s urface, but also to form oxygenates and these findings were in good agreeme nt with the results of catalytic reaction.