Molecular encapsulation of 5, 10, 15, 20-tetrakis (4-methylphenyl) porphyrinato iron (III) chloride (FeTPP) into MIL-101(Cr) for superior CO2/ N2 separation performance

The greenhouse effect associated with excessive CO2 emission has led to a series of environmental issues, thus developing excellent adsorbents for CO2 capture from flue gas offers a sustainable approach. To combine the merit of multiple functional components, novel FeTPP@MIL-101(Cr) was prepared by incorporation of 5,10,15,20-tetrakis(4-methylphenyl)porphyrinato iron (III) chloride (FeTPP) into MIL-101(Cr) cages via in-situ packaging strategy. The cage-confined FeTPP can both regulate the pore structures of MIL-101(Cr) and provide additional binding sites for CO2 adsorption. Profiting from extra interactions for CO2 component and the "sieving effect" for N2 component induced by incorporation of FeTPP, the discrepancy of isosteric heat for CO2 and N2 was largely amplified. Notably, the CO2/N2 selectivity (15/85, v/v) calculated by ideal adsorbed solution theory (IAST) increased from 17.1 (MIL-101 (Cr)) to 41.8 (FeTPP@MIL-101 (Cr) with FeTPP loading of 4.98 wt %) at 273 K, 100 kPa, which is 2.44 times larger than that of pristine MIL-101 (Cr) and also exceeds most reported adsorbents.