A higher methane conversion than those obtained with stoichiometric and lean feed mixtures is observed under rich conditions, during an experiment carried out by performing lean pulses (位 = 1.02) in a constant rich feed gas (位 = 0.98). The analysis of reactants conversion and products distribution suggests that different chemistries are involved under lean and rich conditions. Only reactions of complete oxidation of H2, CO, CH4 and NO occur under excess of oxygen, whereas under rich conditions NO reduction, CH4 steam reforming and water gas shift also occur.
The effect of symmetric oscillation of the exhausts composition around stoichiometry is also addressed by periodically switching from slightly rich to slightly lean composition with different oscillation amplitudes (螖位 = 卤0.01, 卤0.02 and 卤0.03). Higher and more stable methane conversion performances are obtained than those observed under constant 位 operations. The presence of a more active PdO/Pd0 state is suggested to explain the enhancement of catalytic performances.