In the following work, the catalytic behavior of Pd catalysts prepared using different oxides as support (Al₂O₃, CeO₂ and TiO₂) in the catalytic combustion of propene, in low concentration in excess of oxygen, to mimic the conditions of catalytic decomposition of a volatile organic compound of hydrocarbon-type is reported. In addition, the influence of different promoters (Ce, Ti, Fe and Mn) when added to a Pd/Al₂O₃ catalyst was analyzed. Catalysts were prepared by the impregnation method and were characterized by ICP-OES, N₂ adsorption, temperature-programmed reduction, temperature-programmed oxidation, X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy. Catalyst prepared using CeO₂ as the support was less easily reducible, due to the stabilization effect of CeO₂ over the palladium oxides. Small PdO particles and, therefore, high Pd dispersion were observed for all of the catalysts, as confirmed by XRD and TEM. The addition of Ce to the Pd/Al₂O₃ catalysts increased the metal-support interaction and the formation of highly-dispersed Pd species. The addition of Ce and Fe improved the catalytic behavior of the Pd/Al₂O₃ catalyst; however, the addition of Mn and Ti decreased the catalytic activity in the propene oxidation. Pd/TiO₂ showed the highest catalytic activity, probably due to the high capacity of this catalyst to reoxidize Pd into PdO, as has been found in the temperature-programmed oxidation (TPO) experiments.

Metal-doped (Mn, Cu, Ni, and Fe) cobalt oxides were prepared by a coprecipitation method and were used as catalysts for the total oxidation of toluene and propane. The metal-doped catalysts displayed the same cubic spinel Co₃O₄ structure as the pure cobalt oxide did; the variation of cell parameter demonstrated the incorporation of dopants into the cobalt oxide lattice. FTIR spectra revealed the segregation of manganese oxide and iron oxide. The addition of dopant greatly influenced the crystallite size, strain, specific surface area, reducibility, and subsequently the catalytic performance of cobalt oxides. The catalytic activity of new materials was closely related to the nature of the dopant and the type of hydrocarbons. The doping of Mn, Ni, and Cu favored the combustion of toluene, with the Mn-doped one being the most active (14.6 × 10⁻⁸ mol g_Co⁻¹ s⁻¹ at 210 °C; T₅₀ = 224 °C), while the presence of Fe in Co₃O₄ inhibited its toluene activity. Regarding the combustion of propane, the introduction of Cu, Ni, and Fe had a negative effect on propane oxidation, while the presence of Mn in Co₃O₄ maintained its propane activity (6.1 × 10⁻⁸ mol g_Co⁻¹ s⁻¹ at 160 °C; T₅₀ = 201 °C). The excellent performance of Mn-doped Co₃O₄ could be attributed to the small grain size, high degree of strain, high surface area, and strong interaction between Mn and Co. Moreover, the presence of 4.4 vol.% H₂O badly suppressed the activity of metal-doped catalysts for propane oxidation, among them, Fe-doped Co₃O₄ showed the best durability for wet propane combustion.