Enhancing hydrophobicity via core–shell metal organic frameworks for high-humidity flue gas CO2 capture

Developing metal–organic framework (MOF) materials with the moisture-resistant feature is highly desirable for CO2 capture from highly humid flue gas. In this work, a new core–shell MOF@MOF composite using Mg-MOF-74 with high CO2 capture capacity as a functional core and hydrophobic zeolitic imidazolate framework-8 (ZIF-8) as a protective shell is fabricated by the epitaxial growth method. Experimental results show that the CO2 adsorption performance of the core–shell structured Mg-MOF-74@ZIF-8 composites from water-containing flue gas is enhanced along with their improved hydrophobicity. The dynamic breakthrough results show that the Mg-MOF-74@ZIF-8 with three assembled layers (Mg-MOF-74@ZIF-8-3) can capture 3.56 mmol·g−1 CO2 from wet CO2/N2 (VCO2: VN2 = 15:85) mixtures, which outperforms Mg-MOF-74 (0.37 mmol·g−1) and most of the reported physisorbents.