Non-stoichiometric hydrates—III: The relative importance of cations and of anionic framework in determining the energetics of zeolitic water

Abstract

In the range of amount sorbed outside the range where energetic heterogeneity is important, it was found that no clear correlation exists between heat of Sorption of zeolitic water and the cation present in a series of ion-exchanged faujasites. Polarization energy, whether due to charge screening or saturation of induced polarization or both, contributes little to the energy of sorption of argon and probably to that of nitrogen, water or ammonia. Although field-dipole energy for water or ammonia is considerably reduced below the value expected for interaction with isolated ions, it continues to play an important role. In porous, oxygen-rich heteroionic crystals it is the anionic oxygens which for larger amounts sorbed appear to determine the energy of sorption of water, argon or nitrogen, with cations and self-potential exercising moderating influences.