Oscillations of methane oxidation over metallic nickel surfaces

The oscillatory behavior of the reaction of partial oxidation of methane has been investigated over metallic nickel surfaces. It was found that the chemical compositions and the reaction temperature within the reactor exhibited regular oscillations over a range of reactor temperatures between 710 and 930 °C with different feed gas compositions at flow rate ratios (Ar/CH4/O2) ranging from 30:29:1 to 30:12:18 cm3 min−1. When the reactor temperature increased, the oscillation frequency increased showing indicative correlations, while the amplitude decreased with the rise in system temperature. Varying feed gas composition resulted in complex changes in oscillatory waveforms, frequencies, amplitudes, and product selectivities. The oscillation was attributed to the cyclic reduction and oxidation of the nickel surface under the reaction conditions.