Mixed matrix membranes based on NbOF 5 2− anion-pillared porous MOFs for efficient CO 2 separation

CO 2 capture and storage technologies are crucial for environmental conservation and sustainable progress. To overcome the challenging trade-off between permeability and selectivity in polymeric CO 2 separation membranes, we innovatively fabricated mixed matrix membranes (MMMs) by introducing three different NbOF 5 2− anion-pillared porous metal–organic frameworks (MOFs), namely NbOFFIVE-2-Cu-i, NbOFFIVE-2-Ni-i, and NbOFFIVE-bpy-Ni. The CO 2 capture performance of the three MOFs was investigated for the first time, and the ideal adsorption solution theory (IAST) method was used to predict the CO 2 separation selectivity. Density functional theory (DFT) calculations confirmed that the interaction energy between NbOFFIVE-2-Cu-i and CO 2 is the highest among the three MOFs. This is due to the optimal pore dimensions and strong C δ+ … F δ− electrostatic interaction between the C atoms in CO 2 molecules and the F atoms in NOFFIVE-2-Cu-i. The introduction of the three MOFs into the MMMs led to an increase in CO 2 solubility, resulting in enhanced CO 2 permeability and selectivity. The MMM loaded with 2 wt% of NbOFFIVE-2-Cu-i exhibited exceptional CO 2 permeability and CO 2 /N 2 ideal selectivity values of 578 Barrer and 70, respectively, representing enhancements of 39 % and 29 % compared to neat membrane, and exceeding the upper bound established in 2019.