Zeolite-based catalysts have been investigated as a well-known catalyst in a selectively catalytic reduction (SCR), in the conversion of NO to N2 molecule. Here we have performed periodic DFT calculations to simulate pure metal, Cu4, and bimetal Cu3Fe clusters, on the ZSM-5 by introducing a single Al atom in the unit cell of ZSM-5 (Si/Al ratio=95). The calculated results show that the most stable structures of both Cu4 and Cu3Fe clusters in ZSM-5 are both Td configuration. In addition, the NO bond length would be elongated from 1.15 Å to 1.25∼1.30 Å in the adsorption of NO on metal-cluster stabilized zeolites (both Cu4-ZSM-5 and Cu3Fe-ZSM-5), being longer than the counterparts on single-metal anchored zeolites. Furthermore, the calculated NO bond cleavage barrier on Cu3Fe-ZSM-5 was lower than its counterparts on Cu4-ZSM-5. To understand the electronic properties, we performed the calculation of Bader charge analysis and local densities of states, and the result was explicable.
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