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

In this work, sulfation effect on NH3-SCR performance over CeO2 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 CeO2 nanocubes and CeO2 nanorods got greatly enhanced after the sulfation at low-temperature range (< 350 °C). CeO2 nanorods exhibited a much higher NH3-SCR activity than that of CeO2 cubes. However, compared to CeO2 nanocubes, CeO2 nanorods suffered from a severe deactivation when sulfated at higher temperatures (> 350 °C). A series of characterizations such as N2 adsorption–desorption, XRD, HR-TEM, TG–DTA, Raman and in situ DRIFTS of SO2 + O2 adsorption were conducted to investigate the interactions between SO2 and nano-shaped CeO2. It was revealed that the morphology of CeO2 nanorods was damaged severely when sulfated at high temperature (> 350 °C), while the structure of CeO2 nanocubes was relatively stable under the same condition. Furthermore, more sulfate species were found on CeO2 nanorods than on CeO2 nanocubes, in particular of bulk like sulfate species. As a result, the NO removal efficiency of CeO2 nanorods declined greatly when sulfated at high temperature. [ABSTRACT FROM AUTHOR]