Dual-site engineering in EDTA-modified Mg-MOF-74 for effective CO2 capture under humid conditions

Herein, a mixed-linker modification strategy is employed by integrating ethylenediaminetetraacetic acid (EDTA) into the Mg-MOF-74 framework. This approach preserves the original onedimensional pore structure while altering the coordination environment of Mg2+ sites, reducing their coordination number to five.

The resulting structure with uncoordinated oxygen atoms from EDTA serves as exclusive adsorption centers for H2O thereby protecting the CO2 adsorption capacity. The optimized MOFs exhibits a high CO2 adsorption capacity (6.4 mmol/g, at 1 bar) and outstanding CO2/N2 selectivity (346). In humid CO2/N2 (15:85, v:v, at 314 K, RH% = 86%) breakthrough experiment, the EDTA-modified frameworks maintain stable CO2 uptake (3.92 mmol/g), consistent with dry performance, whereas the pristine Mg-MOF-74 shows a great reduction (2 mmol/g).