Site-specific Xe additions into Cu-ZSM-5 zeolite.

Large-scale density functional theory (DFT) calculations found significant preferences of two-coordinated copper cations as Xe binding site in ZSM-5. Such site-preferences cannot be seen in usual adsorbents such as the CO or NO molecule inside Cu-ZSM-5 as well as the Xe atom inside alkali-metal exchanged ZSM-5s. A key factor in the specificity of the inner Xe atom is that interactions of the Xe atom with the extraframework copper cation are substantial relative to the extraframework alkali-metal cases, but weak relative to the CO and NO cases. Since the Xe atom can distinguish two-coordinated copper cations from others, it can be utilized to track sensitively the location of active sites of Cu-ZSM-5.