Ti-chabazite as a model system of Ti(IV) in Ti-zeolites: A periodic approach

For the first time, full ab initio periodic calculations on a Ti-chabazite with a very low content of Ti (Ti/Si=1/11) were done. The simulated crystal is less computationally demanding and it is similar to the real titanosilicates microporous materials such as TS-1 or Ti-β, where the Ti/Si is lower than 1/30, and hence it can be used as a model system. The geometric and energetic features of the interaction of Ti-CHA with NH3, H2O, H2CO, and CH3CN were studied, principally at the Hartree–Fock level. Bare Ti-CHA and its NH3, H2O, H2CO, and CH3CN complexes were fully optimized at Hartree–Fock level with an upgraded version of the CRYSTAL code [Chem. Phys. Lett. 348, 131 (2001)] and such optimized structures were employed to calculate BEc (binding energy corrected for the basis set superposition error) at the Hartree–Fock and B3-LYP levels.