Catalytic conversion of air–methane flow by nanostructured ruthenium dioxide: FTIR spectroscopy and modeling

Nanostructured powders of ruthenium dioxide RuO2 were synthesized via a sol–gel route involving acidic solutions with pH varying between 0.4 and 4.5. The RuO2 nanopowders were characterized by X-ray diffraction. Crystallite sizes measured from X-ray diffraction profiles and TEM analysis varied in the range 8–16 nm, with a minimum of crystallite dimension for pH 1.5. Catalytic conversion of methane by these RuO2 nanostructured catalysts was studied as a function of pH, catalytic interaction time, air methane composition, and catalysis temperature, by the way of Fourier transform infrared (FTIR) spectroscopy coupled to homemade catalytic cell. The catalytic efficiency defined as FTIR absorption band intensities I(CO2) was maximum for sample prepared at pH 1.5, and mainly correlated to crystallite dimensions. A modeling approach of catalytic conversion is proposed for such a specific experimental configuration.