Collect. Czech. Chem. Commun. 1992, 57, 681-686

Molecular Mechanics Studies on MFI Type Zeolites. 2. Isomorphous Substitution by Aluminium

Erik de Vos Burchart, Herman van Bekkum and Bastiaan van de Graaf

Laboratory of Organic Chemistry, Delft University of Technology, Julianalaan 136, 2628 BL Delft, The Netherlands


The molecular mechanics force field developed for all-silica structures is extended with parameters for tetrahedral aluminium. With this force field and the MM3 force field for organic molecules the effects of isomorphous substitution in the MFI framework are examined (4 Al/unit cell) with tetrapropyl ammonium (TPA) as the charge compensating cation. The results indicate a slight preference for the positions 2, 9, 5, 12, and 6 and the by mirror symmetry related positions. The differences in energy are mainly due to the differences in the zeolite framework energy.