Enhanced Catalytic Cycloaddition of Dilute CO ₂ to Cyclic Carbonates via a Nanoporous Metal–Organic Framework under Mild Conditions

The cycloaddition of CO2 to epoxides is an atom-efficient route to the formation of valuable cyclic carbonates. Synthesis of styrene carbonate (SC), a crucial industrial intermediate, from styrene oxide (SO) is challenging and typically requires harsh synthesis conditions due to the low reactivity of SO. In this work, we demonstrate a mild condition and highly efficient SO to SC conversion using nano-ZIF-8 catalysts with nanocube (NC), rhombic dodecahedron (RD), and truncated rhombic dodecahedron (TRD) morphologies. All catalysts delivered >99% conversion and high selectivity under mild, solvent-free conditions (5 bar CO2, 70 °C) with excellent recyclability and displayed broad substrate scope. Importantly, nano-ZIF-8 could drive the reaction even under dilute CO2 (10 vol %) conditions, with high selectivity and conversion. This superior performance is attributed to an optimal balance of Lewis acid–base sites and selective affinity for CO2, supported by permanent porosity that ensures high CO2 preconcentration. This study highlights the strong potential of nano-ZIF-8 for CO2 fixation from realistic CO2 sources, contributing to the CO2 circular economy.