Total Oxidation of Methane over the LaNi_1−xM_xO₃ (M: Mn, Ag, Cu, Co) Perovskites

In this study, the total oxidation reaction of methane, one of the atmospheric pollutants, was studied. For this aim, different metal-doped LaNi_1−xM_xO₃ (x = 0 and 0.5) (M(metal) = Cu, Mn, Co, Ag) perovskites were synthesized for total oxidation of methane. In order to prepare perovskite-type catalysts, two different preparation methods were used, namely co-precipitation method and Pechini sol–gel method. The X-ray diffraction, X-ray photoelectron spectroscopy, N₂ physisorption, inductively coupled plasma optic emission spectroscopy, scanning and high-resolution transmission electron microscopies studies were performed to determine the effects of preparation on the characteristic properties of the catalysts. Total oxidation of methane was carried out on all catalysts using 1% CH₄, 21% O₂ and the remainder He feed condition. The reaction temperature varied between the 300 \(^\circ\)C and 800 \(^\circ\)C. Deactivation tests were performed on the most active catalysts. LaNi_0.5Mn_0.5O₃ prepared by both preparation methods according to 50% CH₄ conversion temperature was found to be the most active catalysts. LaNi_0.5Mn_0.5O₃ catalyst prepared by co-precipitation method gave 50% conversion at 560 °C without pretreatment with O₂. Pretreatment with O₂ did not cause major changes in activity results.