Enhancement of CO2 Adsorption in Magnesium Alkoxide IRMOF-10

Ab initio calculations and GCMC simulations were performed in order to study the CO2 adsorption from Mg modified IRMOF-10. The Mg cations were introduced in the linker of IRMOF-10 by creating Mg alkoxide groups. Accurate MP2 calculations on the Mg alkoxide linker showed that up to 4 CO, molecules can simultaneously interact with the Mg atom of the alkoxide group. The average interaction energy ranged from -14.2 to -8.9 kcal.mol(-1) for one to four interacting CO2. GCMC simulations were also employed using a modified LJ potential in order to predict the excess CO2 adsorption isotherms at 300 K and up to 40 bar. The predicted isotherms showed a clear enhancement of the CO2 uptake when one or two Mg alkoxide groups were introduced per linker with respect to the unmodified IRMOF-10. This enhancement was more pronounced at low pressures. At 10 bar, the volumetric capacity became 5 or 7 times larger than in the case of the unmodified IRMOF-10 by introducing 1 or 2 Mg alkoxide groups, respectively. Based on this significant enhancement, we propose the Mg functionalization as a general strategy for improving the CO2 storage capacity in MOFs and similar materials.