Assessment of a Metal−Organic Framework Membrane for Gas Separations Using Atomically Detailed Calculations: CO₂, CH₄, N₂, H₂ Mixtures in MOF-5

Metal−organic frameworks (MOFs) have emerged as a fascinating alternative to more traditional nanoporous materials. Although hundreds of different MOF structures have been synthesized in powder form, little is currently known about the potential performance of MOFs for membrane-based separations. We have used atomistic calculations to predict the performance of a MOF membrane for separation of various gas mixtures in order to provide information for material selection in membrane design. Specifically, we investigated the performance of MOF-5 as a membrane for separation of CO 2 /CH 4, CO 2 /H 2, CO 2 /N 2, CH 4 /H 2, N 2 /H 2, and N 2 /CH 4 mixtures at room temperature. In every case, mixture effects play a crucial role in determining the membrane performance. Although the membrane selectivities predicted for MOF-5 are not large for the mixtures we studied, our result suggest that atomistic simulations will be a useful tool for considering the large number of MOF crystal structures that are known in order to seek membrane materials with more desirable characteristics.