Catalytic combustion of methane over La 2 BCoO 6 perovskites containing Ni, Cu and Fe: impact of B-sites on oxygen speci
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Catalytic combustion of methane over La2BCoO6 perovskites containing Ni, Cu and Fe: impact of B‑sites on oxygen species and catalytic activity H. Rezaei Shadegan1 · S. Maghsoodi1 · B. Ghanavati1 · A. Shahbazi Kootenaei1 · A. Azimi1 Received: 24 July 2020 / Accepted: 16 September 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract The effect of B-site partial substitution on the structure and the catalytic performance of cobalt-based double perovskites (La2BCoO6 where B = Cu, Ni and Fe) was investigated in the catalytic combustion of methane. The synthesized samples were characterized using XRD, XRF, N 2-physisorption, H2-TPR, O2-TPD, CH4-TPR and XPS techniques. The XRD results showed the successful synthesis of cobalt-based double perovskites with single phase and rhombohedral structure. The incorporation of Ni, Cu and Fe created abundant oxygen vacancies on the double perovskites which improved oxygen mobility and reducibility and accordingly increased the catalytic activity. The catalytic activity of synthesized samples was in the order of La2CuCoO6 > La2NiCoO6 > La2FeCoO6 > LaCoO3. The better activity of La2CuCoO6 was owing to the presence of the highest oxygen species, the highest reducibility and the highest oxygen mobility. Keywords Double perovskite · Catalytic oxidation · Methane · Partial substitution
Introduction Methane as the main component of natural gas is an economical energy source in many industrial processes. However, it along with CO and N Ox appears in many fugitive emissions which needs further process to prevent pollution [1, 2]. Recently, interests in the catalytic combustion of methane has grown because of its higher energy conversion efficiency and ultra-low emissions of pollutants as compared to the conventional flame combustion [1, 3]. Requiring lower temperatures for the catalytic combustion of hydrocarbons causes the formation of less * S. Maghsoodi [email protected] 1
Department of Chemical Engineering, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran
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Reaction Kinetics, Mechanisms and Catalysis
harmful species such as CO or N Ox. Supported noble metal catalysts such as Pd and Pt are conventional catalysts for the conversion of methane. Despite the high activity of these materials, their application has been limited because of high costs, sublimation and sinterisation problems [1, 3–5]. Among the possible substitutes for the noble metals, Perovskite-type oxides have attracted extensive interests because of their high activity and thermal stability in the oxidation of light hydrocarbons. Perovskite-type oxides have a general formula of ABO3 where A is rare earth (mainly La) and B is transition metal such as Cr, Mn, Fe, Co, Ni, etc. [2, 3]. In the catalytic combustion of hydrocarbons, B ion is responsible for catalytic activity, while A ion is responsible for the formation of crystal lattice vacancies and can stabilize different oxidation states for B. The thermal stability of Perovskite-type oxides is also related to
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