Recent advances in CO2 capture and simultaneous conversion into cyclic carbonates over porous organic polymers having accessible metal sites

Abstract

The cycloaddition reaction of CO₂ and various epoxides is one of the most promising approaches for CO₂ fixation. Inspired by the synergistic catalytic mechanism based on the double activation model of an epoxide, it's well documented that most metal-based catalysts often show higher catalytic activities than traditional organocatalysts under identical conditions. As a result, the feasible construction of a series of metal-functionalized porous organic polymers (denoted as metal-POPs) can provide the opportunity for integrating the advantages of homogeneous catalysis for high activity and heterogeneous catalysis for facile recyclability. Indeed, metal-POPs are identified as excellent heterogeneous catalysts for capturing and simultaneously converting CO₂ into cyclic carbonates, thereby affording quite high activities and selectivities. This review describes the recent advancements with regard to the design and synthesis of metal-POPs featuring accessible active sites and then discloses the structure–property relationship in metal-catalyzed CO₂ cycloaddition reactions with epoxides. From the perspective of the design of task-specific monomers and special connectors, we mainly focus on how to introduce metal species into polymer backbones. Also, we discuss multifunctionalization of metal-POPs through the introduction of functional groups including CO₂-philic heteroatoms and ionic moieties. Consequently, current challenges and future research efforts are further elaborated for the requirement of practical industrial applications.