Assessing the role of oxygen vacancies on N2O catalytic decomposition over CaMn1-xFexO3-δ perovskites

Catalytic decomposition of N 2 O using redox perovskites can efficiently mitigate industrial emissions of this molecule. Here, we have selected the CaMn 1-x Fe x O 3-δ (CMF) oxides as catalysts to explore the role of oxygen vacancies on N 2 O decomposition, because for these materials the thermodynamics of oxygen non-stoichiometry is known in detail Perovskites with two levels of Fe-doping, CMF73 (30 % at.) and CMF91 (10 % at.), were prepared and extensively characterized. Higher conversion is obtained over CMF73, which also presents good stability. In the presence of N 2 O, variation of temperature prompts this perovskite to quickly adjust the value of δ by reversible release/uptake of O 2 . In parallel, surface vacancies can participate in the breaking of the N-O bond, as a part of a regenerative catalytic cycle yielding N 2 and O 2 . A simple kinetic model shows good correlation between the number of oxygen vacancies, estimated by δ, and the catalytic activity, explaining the better performance of CMF73. • Perovskites CaMn 1-x Fe x O 3 show moderate activity for the catalytic decomposition of N 2 O. • The best performance corresponds to the perovskite CaMn 0.7 Fe 0.3 O 3 , which shows structural stability under reaction. • Higher activity of CMF73 can be related to higher density of oxygen vacancies of that perovskite. • A simple kinetic model that considers the role of oxygen vacancies fits the results of catalytic tests satisfactorily.