Pd–Ce0.33Zr0.67O2–Al2O3 catalyst for propane oxidation: Interactions between the precious metal and support under the hydrothermal ageing

• The mixing mode influences C3H8 oxidation activity of Pd–CeZr–Al2O3 obviously.
• No Pd migration to another support is observed after hydrothermal aging.
• The Pd-another support interface is enlarged on the co-ageing samples.
• The nature of Pd-support interaction was attributed to an electron transfer effect.

To investigate the influencing of the Ce0.33Zr0.67O2 and Al2O3 supports on the catalytic activity of Pd catalysts for propane oxidation, and possible Pd migration/interaction on different supports during the hydrothermal ageing, four samples were prepared by mixing one supported catalyst and another support powders either before or after the ageing treatment in a steam-containing air at 1050 °C for 5 h. It is unlikely for the occurrence of migration of Pd from one support to another during the thermal treatment as evidenced by the SEM and EDS results. IR spectra after CO introduction and H2-TPR results indicate the enlargement of the interface between Pd and another support during the thermal ageing, which may result in different Pd-support interaction. TPHD and XPS results further attribute the nature of this interaction to an electron transfer effect. The propane light-off temperature of co-aged Pd/Ce0.33Zr0.67O2 and Al2O3 is 45 °C lower than the mixture of aged Pd/Ce0.33Zr0.67O2 and Al2O3, indicating the Pd–alumina interface is found to be more effective for the catalytic oxidation of propane.

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