Iron-Based Trimetallic Metal–Organic Frameworks as Efficient Catalysts for Fixation of CO₂ into Cyclic Carbonates

The fact that carbon dioxide (CO2) is converted into high-value cyclic carbonates from the viewpoint of a dual carbon target has garnered wide attention. In this work, monometallic Fe3-MOF and a series of bimetallic FexCoy-MOF (x:y = molar ratio of Fe to Co) materials are successfully obtained. They, as Lewis acid catalysts, realize highly effective cycloaddition reactions of CO2 with epoxides under solvent-free reaction conditions and atmospheric pressure. Among them, bimetallic FeCo2-MOF with an Fe/Co molar ratio of 1:2 exhibits the best catalytic performance toward CO2 cycloaddition reaction and can reach conversions of up to 99% at optimal conditions (80 °C, 8 h, 0.1 MPa CO2), which is far better than with monometallic Fe3-MOF and previously reported related systems. As-designed contrast experiments fully demonstrate the synergistic effect of Fe/Co centers in target bimetallic FexCoy-MOF. The corresponding reaction mechanism is deeply analyzed and discussed. In summary, this work provides a simple and environmentally friendly synthetic strategy proposed by us to boost the catalytic performance of the CO2 cycloaddition reaction.