Time-Dependent Oxidative Capacities ofLa2O3,Lu2O3,CeO2, andBi2O3Materials Interacting with Air-CO or Air-CH4Flows

摘要

Using Fourier transform infrared (FTIR) spectroscopy analyses, we have studied the oxidation processes of methane or carbon monoxide in air-CH4or air-CO flows interacting with polycrystalline catalytic oxides, as a function of temperature(T)and time(t). The gas flows crossed through La2O3, Lu2O3, CeO2, or Bi2O3porous walls with constant composition and rate. The oxidation capacities of materials were determined from the intensitiesI(t,T)of CO2vibrational bands resulting from the total oxidation of CH4or CO into CO2. To interpret the time-dependent variations of these intensities, we have applied a model derived from Johnson-Mehl-Avrami approaches. This simple approach delivers pertinent parameters describing time-dependent oxidation rates.