Catalytic combustion of methane over barium hexaferrites

Abstract

Barium hexaferrite BaFe12O19 and iridium-containing barium hexaferrites have been prepared by the citrates gel method. Their catalytic activity in methane combustion has been evaluated. BaFe12O19 is an efficient catalyst for this reaction, and the introduction of iridium in the hexaferrite structure does not improve this activity. Mossbauer spectroscopy suggests that a part of the iridium ions are incorporated in the hexaferrite structure, however in crystallographic sites where they cannot interact with the gas phase. Infrared study of CO adsorption reveals the presence of two types of iridium particles in the surface: small Ir particles, in strong interaction with the hexaferrite structure, and some larger Ir particles which were not incorporated into the lattice.