Molecular simulations were made of adsorption equilibria and diffusivities of pure and mixed gases of ethanol/water in micropores of NaA zeolite crystals by using μVT-ensemble orientational-bias Monte Carlo and NVT-ensemble equilibrium molecular dynamics techniques. The temperature and total pressure were set at 378K and 0.1MPa, respectively. The diffusivity of water in the zeolite was found to be in the range of 3.9 x 10-10 to 7.9 x 10-10m2/s, while the ethanol molecules were confined to the α-cage and did not go through the window during a simulation period of 3ns. This indicated that the diffusivity of ethanol might be much smaller than that of water. It was concluded that the high permselectivity of water through an NaA zeolite membrane was due to the cooperation a high adsorption selectivity and a high water diffusivity. It was noted that the selective adsorption of water could be important for preventing blockage by ethanol molecules of the entrance and inside of the membrane.

Molecular Simulation Study on Adsorption and Diffusion Behavior of Ethanol/Water Molecules in NaA Zeolite Crystal. S.I.Furukawa, K.Goda, Y.Zhang, T.Nitta: Journal of Chemical Engineering of Japan, 2004, 37[1], 67-74