High temperature conduction and methane conversion capability of BaCeO3 perovskite

The transport properties and reactivity in gases of a BaCeO3 perovskite phase have been investigated to develop new materials for methane conversion in microsystems. The polycrystalline material has been synthesized at moderate temperature using a specific modified EDTA-citrate complexing methodology. The BaCeO3 phase has been characterized by X-ray diffraction (XRD), thermogravimetry and differential thermal analyses (TG/DTA), scanning and transmission electronic microscopy techniques (SEM, TEM), energy dispersive X-ray (EDX) and surface area analyses. A Rietveld analysis of diffraction profiles has allowed determining the structural parameters of the as prepared material. Next, the catalytic efficiency of the BaCeO3 phase with air-methane gas flows has been characterized by Fourier transformed infrared (FTIR) spectroscopy: the conversion rate of CH4 into CO2 has been determined from the intensities of CO2 absorption bands, as a function of temperature (from 450 to 750 °C) and reaction time. Finally, the electrical conduction of compacted BaCeO3 pellets has been determined from electrical impedance spectroscopy analyses between 300 °C and 950 °C. A series of electrical transitions correlated with well known structural changes has been observed between 300 °C and 950 °C. The starting catalytic activity of BaCeO3 might be correlated to the enhanced ionic conduction observed above 450 °C.