Fig. 2: CO2 capture properties of PEI-functionalized MIL–101(Cr).

a CO2 isothermal mass adsorption curves at various temperatures (30−90 °C). b CO2 volumetric isothermal adsorption curves at various temperatures (5−90 °C). c Differential scanning calorimetry curve of PEI-functionalized MIL–101(Cr) regeneration. (the blue-shaded region represents the regeneration energy consumption) d Extended CO2 uptakes of PEI-functionalized MIL–101(Cr) with 55 wt.% PEI. (Adsorption in pure 100% CO2 at 30 °C for 15 min; regeneration in pure 100% Ar or CO2 at 150 °C for 15 min).