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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