Computational comparison of the application of doping, functionalization and ion exchanged of adsorbent structures on the pressure swing adsorption

In this work, a grand canonical Monte Carlo (GCMC) simulation was performed to evaluate the performance of three types of modifications on the adsorption isotherms of pristine and modified crystal structures of two metal organic frameworks (MOFs) of Zn-MOF-74 and Zn-IRMOF-13. These modifications were: (i) doping by nickel and magnesium ions, (ii) functionalization with OH, CH3, and NH2 groups, and (iii) ion exchange with magnesium and copper ions. The CO2 working capacity, CO2/N2 selectivity, and selection parameters of each pristine and modified structures was calculated. The results showed that among all of modified structures, the copper ion exchange modification of Zn-MOF-74 has the largest selection parameter of 2858 and 250, and this modification can increase the selection parameters by 590 and 455% than the pristine structure, in the pressure ranges of 10–100 kPa, and 100–1000 kPa, respectively. Therefore, among all of structure modifications studied in this work, the adsorbent structure modification with copper ion exchange and the application of Cu-MOF-74 is the most appropriate for both vacuum and pressure swing adsorption processes.