Light alkane oxidation over Ru supported on ZnAl2O4, CeO2 and Al2O3

Zinc aluminate, alumina and ceria supported ruthenium catalysts were tested in the total oxidation of propane, n-butane and iso-butane. Structure of the catalysts was characterized by means of XRD, TEM, BET and H2 chemisorption techniques. The Ru dispersion changes from 0.67 for 5% Ru/CeO2, 0.56 for 4.5% Ru/ZnAl2O4 and to 0.28 for 4.7% Ru/γ-Al2O3 catalyst. TEM and XRD results confirmed high dispersion of the samples. All oxidation reactions occur at much lower temperatures over Ru/CeO2 compared to those over Ru/γ-Al2O3 and Ru/ZnAl2O4. Also, the site-time yields of all catalysed oxidation reactions follows the order Ru/CeO2 > Ru/γ-Al2O3 > Ru/ZnAl2O4. Activity results cannot be explained by the differences in the Ru dispersion. The redox species of ruthenium on CeO2 oxide, easily reacted with the lattice oxygen of CeO2, are responsible for the enhanced activity of the Ru/CeO2 catalyst in the VOCs oxidation.