Separation of noble gases using CHA-type zeolite membrane: insights from molecular dynamics simulation

Separation of krypton/xenon is an important issue in some industrial applications. This study evaluates the performance of chabazite (CHA) zeolite membrane for krypton/xenon separation using molecular dynamics simulations. The permeation process was investigated at different temperatures (298, 323, 348, and 373 K) and applied pressures up to 25 MPa. The obtained results demonstrated high selectivity for Kr atoms; thus, only Kr atoms can permeate through the CHA membrane by applying external pressure. Permeation of Kr increased by increasing the temperature, but there was an optimum point for applied pressure. The best permeation (6.93 × 10⁻⁵ mol/(m² s Pa)) was obtained at P = 3 MPa and T = 373 K. However, some simulations were performed at high temperature (700 K) and found higher permeation. The potential of mean force (PMF) of Kr and Xe atoms was also calculated to study the capability of CHA membrane for the separation of Kr/Xe gas mixtures. The results of PMF indicated that the driving force is needed for the permeation of Kr or Xe through the CHA membrane. Xenon atom could not easily pass through the membrane in comparison with Kr atom, which was also confirmed by simulation results.