Insights into the Reactivity of La1−x Sr x MnO3 (x = 0 ÷ 0.7) in High Temperature N2O Decomposition

Abstract

In this paper a wide range of La1−x Sr x MnO3 (x = 0–0.7) perovskites was synthesized by Pechini route, characterized by XRD (including high temperature measurements), XPS, differential dissolution phase analysis, TPR H2, oxygen exchange and tested in N2O decomposition at 900 °C. At low degree of Sr substitution for La (x ≤ 0.3), high catalytic activity was found for perovskites with hexagonal structure (x = 0.1–0.2) and can be related to fast oxygen mobility caused by the lattice disordering during polymorphic phase transition from the hexagonal to cubic structure. For multiphase samples (x > 0.3) increase of activity and oxygen mobility can be attributed to the formation of the layer-structured perovskite–LaSrMnO4 on the surface. Catalytic activity of La–Sr–Mn–O samples in high-temperature N2O decomposition is discussed with emphasis on its relation to oxygen mobility, surface composition and microstructure of the catalyst particles.