Using classical molecular dynamics simulations, a study was made of structural and diffusive properties of water molecules adsorbed in chabazite (figure 9). In particular, an investigation was made of the variation of the self-diffusion coefficient of the water molecules as a function of their concentration and the nature of the hydration shells of the extra framework Ca2+ ions with varying concentrations of water. The study indicated that the well-defined and stable hydration shells of this ion played an important role in the diffusion process. The diffusion anisotropy was computed for temperatures greater than 600K. It was compared with theoretical results based upon jump models and compared qualitatively with pulsed field gradient nuclear magnetic resonance data on a single chabazite crystal at 293K, and with tracer diffusion studies. Structure and Self-Diffusion of Water Molecules in Chabazite: a Molecular Dynamics Study. S.Jost, P.Biswas, A.Schulring, J.Kalrger, P.A.Bopp, R.Haberlandt, S.Fritzsche: Journal of Physical Chemistry C, 2007, 111, 14707-12

Figure 9

Diffusivity of Water in Chabazite