| Abstract: | The effect of hydration and benzene adsorption on resonance and the quadrupolar interaction in NaY zeolites is studied by triple-quantum MAS NMR spectroscopy. In the case of a C6D6/NaY system, the results show that with an increase in benzene loading, there is an up-field trend in isotropic chemical shift (δCS) and a decreasing second order quadrupolar effect (χs) for the site II sodium ions. It was found that adsorbed benzene molecules have a slight effect on the environment of sodium ions on site I. All the sodium sites in NaY are influenced upon hydration. The up-field shift of the sodium δCS reflects the effect of coordination of oxygen atoms on sodium cations due to hydration. The magnitude of χs for hydrated sodium sites increases and then falls off with water loading. The increase in χs is due to the initial hydration among SI-, SI′- and SII-sodium ions, while the decrease is the result of approaching the final stage of saturated hydration. |
