Inelastic neutron scattering studies of water in natural zeolites

Results on the motion of water molecules in six natural zeolites (natrolite, phillipsite, harmotome, heulandite, stilbite and chabazite) from incoherent inelastic neutron scattering are presented. The spectra for five zeolite samples exhibit broad maxima and few resolved peaks. Only for natrolite with water molecules tightly bound to the alumosilicate framework a spectrum with well-resolved peaks is observed. A detailed interpretation is attempted for the Ba-zeolite harmotome where data were recorded at various temperatures and different amount of water. - Differential scanning calorimetry gave a broad dehydration peak for chabazite (T=443 K) and a sharp single peak for natrolite (T=633 K), whereas three maxima (T=433, 523 and 673 K) were observed for harmotome. (orig.)