Comparative study of MOFs and zeolites for CO₂ capture and separation at process conditions

We present a systematic computational comparison of several types of MOFs vs. zeolites and other materials for gas storage and CO₂ purification. The work focuses on CO₂ capture and separation from multicomponent mixtures in flue gas streams, evaluating the behavior of the materials at industrial conditions, and the impact that impurities have on the process. A first screen was done based on adsorption isotherms and isosteric heats of adsorption, calculated from Grand Canonical Monte Carlo simulations for pure components (CO₂, N₂, O₂, H₂O and SO₂), binary and multi-component mixtures. Predicted selectivities were evaluated and complemented with breakthrough curves and working capacities for PSA/TSA processes among the different frameworks, with and without impurity traces. Results show that Mg-MOF-74 stands up as the most promising material to be used in PSA and TSA processes; however, considering its current availability to large scale and its cost, the zeolite 13X (NaX) still remains, at present, as a the preferred candidate for the industrial process (specially for VSA systems). This work highlights the use of molecular simulations for optimizing environmental related processes, focused on CO₂ capture and separation. It provides new procedures to assess the use of these materials from their fundamental knowledge to their final implementation.