Theoretical Study of CO₂/N₂Gas Mixture Separation through a High-Silica PWN-type Zeolite Membrane

PWN is classified as a member of the second generation of the RHO zeolite family, which is extended by embedding isoreticular structures. Here, we report the performance of a pure silica PWN-type (Si-PWN) zeolite membrane for separation of nitrogen (N2) and carbon dioxide (CO2) gas molecules using molecular dynamics simulations. The simulations were performed at different temperatures and applied pressure up to 10 MPa. It is found that the N2 molecules can easily penetrate through Si-PWN, whereas no CO2 molecule passage was seen owing to the strong van der Waals (vdW) interactions between CO2 molecules and the Si-PWN membrane. Hence, the results suggested that Si-PWN has a very high selectivity of N2 over CO2. Furthermore, the best N2 permeance of 7.24 × 105 GPU across the membrane was obtained at 348 K and 0.25 MPa, which indicates the remarkable performance of Si-PWN in N2/CO2 separation.