| 초록 |
Passive NOx adsorber (PNAs) is a practical solution to the NOx slip during cold start periods. PNA adsorbs NOx at low temperatures and releases NOx at high temperatures where other catalytic conversions can fully function. Several materials, including metal oxides and zeolites, have been intensively studied as possible PNA materials. To understand the pros and cons of each material in industrial application, it's worth comparing different materials that can function in the same way. Here, we studied how two representative PNA materials, Pd/CeO2 and Pd/SSZ-13, adsorb and desorb NOx. Temperature programmed desorption tests were performed at various NO/NO2 ratios. NO2 and NO adsorb competitively over Pd/SSZ-13, whereas NO2 promotes NO adsorption over Pd/CeO2. This phenomenon is due to the nature of the adsorption site. The effects of CO and sulfur treatment were also investigated for Pd/CeO2 and Pd/SSZ-13. |
