摘要

Experimentally, Cu-exchanged IM-5 zeolite has been found to exhibit excellent catalytic activity in NO reduction. Unfortunately, the origin of such property still remains obscure due to the rather complex structure of IM-5. In this paper, we made the first attempt to provide a theoretical rationalization. By calculating the (Al, Cu) location energies. the stability of both Cu2 and hydroxyl-Cu2 (i.e., [CuOH]( )) was considered and compared to those in ZSM-5. It was shown that [CuOH]( ) located in IM-5 is comparable to that in ZSM-5. The most favorable location of Cu2 cation is in 6-membered ring in the wall of unusual two-dimensional medium-pore channel of IM-5. Moreover, through calculating the interaction of NO with copper-exchanged zeolite (Cu-IM-5), the most active center is Cu2 located in the 5-membered ring. The relatively high adsorption energies and numerous active centers in Cu-IM-5 might rationalize why Cu-IM-5 is more active than Cu-ZSM-5 in experiment of NO reduction. Thus, our theoretical results provide support that Cu-IM-5 is a more active and hydrothermically more stable catalyst than Cu-ZSM-5.

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