Influence of residual water on the adsorption of atmospheric gases in Li-X zeolite: Experiment and simulation

Li-LSX zeolite (Si/Al = 1.0) is currently the best sorbent in use in the separation of air by adsorption processes. In this present work we have synthesized fully exchanged Li-LSX zeolite and measured the room-temperature equilibrium adsorption isotherms for N₂, O₂, and Ar after various degrees of dehydration. The effect of the residual water on the adsorption of these atmospheric gases was then simulated using Monte Carlo techniques. Very small amounts of water in the Li-LSX zeolite have a significant effect on the adsorptive capacity of these atmospheric gases with the capacity for N₂ dropping from ≈ 17.4 molecules of N₂ adsorbed/unit cell for the fully dehydrated material to <2 molecules of N₂ adsorbed/unit cell when the sample contained 32 residual water molecules/unit cell, an indication that the N₂ molecules only interact with the supercage SIII Li⁺ cations.