Morphology-Sensitive Sulfation Effect on Ceria Catalysts for NH3-SCR

In this work, sulfation effect on NH3-SCR performance over CeO(2)with different morphology (nanocubes and nanorods) was carefully studied. A morphology-sensitive sulfation effect on NH3-SCR activity was observed on CeO2. Interestingly, the NO removal efficiencies of CeO(2)nanocubes and CeO(2)nanorods got greatly enhanced after the sulfation at low-temperature range (< 350 degrees C). CeO(2)nanorods exhibited a much higher NH3-SCR activity than that of CeO(2)cubes. However, compared to CeO(2)nanocubes, CeO(2)nanorods suffered from a severe deactivation when sulfated at higher temperatures (> 350 degrees C). A series of characterizations such as N(2)adsorption-desorption, XRD, HR-TEM, TG-DTA, Raman and in situ DRIFTS of SO2 + O(2)adsorption were conducted to investigate the interactions between SO(2)and nano-shaped CeO2. It was revealed that the morphology of CeO(2)nanorods was damaged severely when sulfated at high temperature (> 350 degrees C), while the structure of CeO(2)nanocubes was relatively stable under the same condition. Furthermore, more sulfate species were found on CeO(2)nanorods than on CeO(2)nanocubes, in particular of bulk like sulfate species. As a result, the NO removal efficiency of CeO(2)nanorods declined greatly when sulfated at high temperature.