| 초록 |
Ceria-supported Pd nanoparticles were known to be efficient catalysts for vehicle exhaust purification, especially diesel oxidation. The exhaust often undergoes harsh conditions, suffering from high temperature up to ~750 ˚C. These conditions cause Pd nanoparticles sintered, losing the catalytic active sites. In addition, carbonate and sulfate species might be formed on the catalyst surface, blocking the active sites with degraded activity. Hydrothermal treatment on the Pd/CeO2 affected the catalyst structure, resulting in enhanced catalytic activity and durability for CO oxidation. CO conversion approached 100% at the temperature lower than 150 °C even in the presence of propylene or SO2. The high activity for CO conversion was changed little for longer reaction time and even for temperature fluctuation up to 850 °C. The promoting effect was obtained due to Pd re-dispersion and surface hydroxyl groups formed after the hydrothermal treatment. The re-dispersion was confirmed by HADDF-STEM, XRD, in-situ DRIFT, CO chemisorption, and the suppression of surface-poisoning species was investigated using in-situ DRIFT and TPD. |
