Optimization of O₂/CH₄ to oxide methane at 823 K by alumina-ceria supported Pt catalysts

Methane oxidation was carried out in presence of synthetized Pt/Al₂O₃–CeO₂ catalysts with ceria contents between 1 and 37 mol%, at 823 K, 52,000 h⁻¹ of GHSV, by varying the oxygen concentration from a deficient concentration respect to methane (1 mol:1 mol) up until a 100% excess over the stoichiometric (4 mol:1 mol). The catalysts were characterized by TGA, N₂ sorption, XRD, TPR, UV–Vis, TPD-NH₃, and ICP for elemental composition, while methane conversion was followed by gas chromatography. It was found that the optimum concentration of oxygen is the stoichiometric one, and, depending on the concentration of ceria in the catalyst, the operation window with defect and excess of oxygen is different. Particularly, at the highest concentration of ceria in the catalyst, the conversion of methane is greater than using other catalytic materials, and this behavior was attributed to the higher concentration of surface ceria, greater oxygen mobility as well as the synergistic ceria-alumina-platinum effect toward hydrocarbon oxidation.