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

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 degrees C for 5h. 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 H-2-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 degrees 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. (C) 2014 Elsevier B.V. All rights reserved.