CO2 capture from wet flue gas using a water-stable and cost-effective metal-organic framework

We report the use of MIL-120 as a water-stable and cost-effective metal-organic framework (MOF) for selectively capturing CO2 from wet flue gas. Synthesized using inexpensive and environmentally benign reagents in water, MIL-120 possesses one-dimensional pores decorated with hydroxyl-bridged Al(III) ions and benzene rings with an interstitial spacing of 4.78 Å. Carbon dioxide isotherms show steep uptake at low pressure, and the affinity of MIL-120 for CO2 is 44 kJ mol−1. CO2-loading 13C solid-state nuclear magnetic resonance and Fourier transform infrared spectra tracking the sorption of CO2 into MIL-120 revealed that the interplay of pore size, functionality, and dimensionality is vital for CO2 restriction within the pores of MIL-120. Breakthrough experiments reveal that MIL-120 can capture CO2 from dry and wet flue gas with uptake capacities of 1.215 and 1.118 mmol g−1, respectively. Our work highlights the synthetic benefits of MIL-120 and elucidates its selective capture of CO2 from wet flue gas.