Heterogeneous catalytic conversion of carbon dioxide and epoxides to cyclic carbonates

The catalytic conversion of CO2 using thermochemical and photochemical methods is a potential technology for reducing CO2 concentration while obtaining high value-added chemicals. Among them, the efficient and atom-economic methods for CO2 conversion and utilization is the cycloaddition reaction between CO2 and epoxides, which leads to the formation of cyclic carbonates. For this purpose, porous crystal frameworks such as metal organic frameworks (MOFs) and covalent organic frameworks (COFs) have been extensively studied. These frameworks are characterized by their well-designed pores, chemical compositions, high surface area, eminent CO2 adsorption capacity, and adjustable active sites. As a result, they hold great potential as catalysts for CO2 conversion. This review summarizes the research progress of transition metal doped MOFs and COFs in thermal and photocatalytic CO2 epoxide cycloaddition in recent years, as well as describes the structure-activity relationship, providing guidance for designing effective catalysts. Foremost, the main sources and hazards of carbon dioxide were introduced, the technologies for carbon capture and utilization were summarized, as well as a brief discussion was conducted on cyclic carbonates. The recently reported MOFs catalyst system was discussed in the second part of the article, including whether the presence of cocatalysts or not. The third part studied the catalytic performance of COFs materials doped with transition metals. For these two types of catalyst systems, this article highlights the structural characteristics, mechanism of action, significant parameters including substrate range, yield, optimal temperature, pressure, and catalyst loading. By combining this information, the article provides a comprehensive understanding of these catalyst performance. This enables readers to compare different catalysts critically depending on the most important parameters. We concluded by talking about a number of issues linked to the study of MOFs and COFs and anticipating potential opportunities for creating efficient porous frameworks for CO2 adsorption and conversion.