The influence of aluminium concentration on the hydration of ZSM-5-type zeolites in aqueous suspensions

The H-1 NMR spectral technique has been applied to the study of samples of ZSM-5-type zeolites. These samples were synthesized using the template proc edure and possessed various aluminium concentrations in their crystal latti ce. The characteristics of the adsorbed water layers and the values of the free surface energy of the adsorbents were determined. It was established t hat, for aqueous suspensions of zeolites. the highest concentration of wate r in the pores was characteristic of the sample containing the lowest amoun t of aluminium. It was suggested that the amount of water in the pores is d etermined not so much by the concentration of primary adsorption sites as b y the conditions under which the development of water clusters occurs as we ll as by the competing sorption of water and ambient air.