Amine-Grafted MIL-101(Cr) via Double-Solvent Incorporation for Synergistic Enhancement of CO2 Uptake and Selectivity

Recent research on the amine-grafted metal-organic frameworks has obviously spurred intriguing application prospects in the field of CO, capture; however, few of them focused on the synthetic approach, which directly determines their structural stabilities for the application. This work explores a double-solvent incorporation strategy to rapidly squeeze the molecule-level amines into the cavites of MIL-101(Cr) without any framework destruction of MOFs. Tris(2-aminoethyl) amine (TAEA), ethylenediamine (ED) and triethylene diamine (TEDA) were employed to obtain TAEA@MIL-101(Cr), ED@MIL-101(Cr) and TEDA@MIL-101(Cr), respectively. Notedly, the CO, uptake of TAEA@MIL-101(Cr) could be 1.5 times as high as that of pure MIL-101(Cr) at 273 K with a superhigh adsorption heat. Most importantly, the CO2/CO selectivity of TAEA@MIL-101(Cr) was drastically increased, which was 103 times higher than that of MIL-101(Cr). The experimental and theoretical simulation results indicated the different adsorption mechanism of CO2 in the three amine-grafted MIL-101(Cr) materials.