Collect. Czech. Chem. Commun. 2003, 68, 1848-1860

Theoretical Study of Pyrrole Interaction with Alkali Metal Exchanged Zeolites: Investigation of the Reliability of Cluster and Periodic Models

Jan Kučera and Petr Nachtigall*

J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic and Center for Complex Molecular Systems and Biomolecules, Dolejškova 3, 182 23 Prague 8, Czech Republic


The interaction of pyrrole with the alkali metal exchanged zeolites was investigated using cluster models of various sizes and with a hybrid quantum mechanics/interatomic potential function model (QM-pot). The interaction of pyrrole with the M+/zeolite is dominantly driven by the interaction of pyrrole π-system with the alkali metal cation. Further stabilization is due to the formation of the hydrogen bonds between NH and framework oxygen atoms. A good agreement between calculated and experimental shift of the N-H stretching vibration upon the adsorption of pyrrole in M+/zeolite was found with the periodic QM-pot model. The performance of the cluster models for the description of pyrrole interaction with M+/zeolite is discussed. Reliable results can be obtained only when large cluster models are used for description of the zeolite framework.

Keywords: Heterogeneous catalysis; Zeolite; ZSM-5; Alkali ions; Probe molecule; Pyrrole; IR; N-H stretching vibrations; Quantum chemistry; QM-pot; DFT; B3-LYP; Core-shell model potential; Cluster models.

References: 19 live references.