Ranking of Metal Organic Frameworks (MOFs) for Separation of Hexane Isomers by Selective Adsorption

The work presented in this article is aimed to assess the performances of 4763 Metal Organic Frameworks (MOFs) for separation of hexane isomers using computer simulation methods. These MOFs, taken from the Computational Ready Experimental (CoRE) MOF database, are ranked on the basis of various performance metrics, namely, adsorption selectivity, working capacity, and regenerability. We investigated six binary mixtures, one three-component equimolar mixture, and one five-component equimolar mixture of hexane isomers at temperatures of 383, 433, 483, and 533 K. The MOFs were ranked separately for separation of each of these mixtures. The rankings with respect to these three metrics were found to be mostly different with only a few MOFs in common. We also carried out the rankings at different temperatures close to the typical isomerization reactor temperature. It is observed that the orders of the rankings at different temperatures are different. However, the majority of the MOFs are found to be common in the rankings at different temperatures. MOFs BIMDOR and WAMRINO1 perform the best with high adsorption selectivity for all the mixtures. It is observed that the MOFs with very high adsorption selectivity do not have high working capacity and regenerability. However, MOFs VEHJOJ, VEHJUP, and NAYGUR are found to be potential candidates for practical application of separation of the hexane isomers as they have regenerability >80% and reasonably high working capacity and adsorption selectivity. Further, we looked at various structures' property correlations. These correlations reveal that the largest cavity diameter and pore volume are crucial structural properties to be adjusted for obtaining the best performing MOF structure with high selectivity, high working capacity, and high regenerability. MOFs with a largest cavity diameter close to 10 A show high values of selectivity, working capacity, and regenerability.