### Abstract

The distributions of Al tetrahedral sites are studied as a function of Si : Al ratio (from 11 to 95) in three zeolites: ZSM-5, ferrierite, and mordenite. Al configurations obeying Loewenstein's rule are generated by a Monte Carlo procedure and analyzed in terms of accessibility to specific channels. The distribution of pairs of Al sites accessible to the same channel segregates into distinct nearest-neighbor and ring-bridging types. Such pairs provide favorable binding environments for extraframework MO_{x}M^{2+} cations in the metal-ion-exchanged forms of the zeolites. In all three zeolites, the probability of a given Al site having at least one suitable partner for pairing within 8.5 Å is close to unity for typical Si : Al ratios. The probability at shorter distances is more sensitive to the zeolite structure, reflecting the larger number of highly puckered five-and six-membered rings in ZSM-5. This sensitivity, and its implications for CuO_{x}Cu^{2+} formation in the three Cu-exchanged forms, may explain why Cu-ZSM-5 is the most active of the three for catalytically decomposing NO.

Original language | English (US) |
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Pages (from-to) | 85-93 |

Number of pages | 9 |

Journal | Catalysis Letters |

Volume | 68 |

Issue number | 1-2 |

DOIs | |

State | Published - Aug 2000 |

### Keywords

- Al pairs
- Cu oxocations
- Ferrierite
- Monte Carlo sampling
- Mordenite
- NO decomposition
- ZSM-5
- Zeolites

### ASJC Scopus subject areas

- Catalysis
- Chemistry(all)

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## Cite this

*Catalysis Letters*,

*68*(1-2), 85-93. https://doi.org/10.1023/a:1019066916541