Synthesis of Fe-ZSM-5@Ce/mesoporous-silica and its enhanced activity by sequential reaction process for NH3-SCR

•The loading of Ce effectively improves the oxygen activation and NO oxidizability.•The mesoporous silica shell promotes the dispersion of ceria and results in strong redox ability of samples.•The sequential reaction including NO oxidation process is beneficial to enhance SCR reaction rate in fast SCR process.

As an excellent NH3-SCR catalyst, Fe-ZSM-5 suffered from its inferior performance at lower temperature region. Efforts have been made to improve the low/medial-temperature reaction rate of it. In this work, a sequential reaction strategy relied on a core-shell structure zeolite with Fe-ZSM-5 core and ceria loaded mesoporous-silica shell was proposed. It was confirmed that a considerable portion of NO was pre-oxidized to NO2 when the mixture gas passed through the ceria loaded mesoporous silica shell which leads to the occurrence of fast-SCR process on Fe-ZSM-5 core. As expected, the ceria loaded mesoporous-silica shell acted as an oxidation reactor for NO and the Fe-ZSM-5 core was the real location where fast-SCR took place. To emphasize such a sequential reaction, the process of diffusion and the necessity of ceria loaded mesoporous silica shell were further discussed and confirmed by TPD and in situ DRIFTS.

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