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 multi-component 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.