Self-oscillations of methane oxidation rate over Pd/Al2O3 catalysts: Role of Pd particle size

• CH4 oxidation rate over Pd/Al2O3 oscillates in a certain temperature interval.
• The oscillation interval narrows as Pd particle size decreases.
• At the same time, the period of oscillations showed ca. 6-fold increase.

Oscillations of the methane oxidation rate were studied under methane-rich conditions on Pd/Al2O3 catalysts differing in Pd particle size. It was demonstrated that the temperature interval where oscillations occur narrows from 300–360 °C for the catalyst with Pd particle aggregates from 50–100 nm to 345–355 °C for the catalyst with isolated Pd particles of ~ 5 nm in size. At the same time, the period of oscillations showed ~ 6-fold increase. Structural transformations of Pd in the oscillation cycle were similar to those observed on bulk Pd used as a catalyst in the same reaction.

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