CO₂-Based Stable Porous Metal–Organic Frameworks for CO₂ Utilization

Abstract

The transformation of carbon dioxide (CO₂) into functional materials has garnered considerable worldwide interest. Metal-organic frameworks (MOFs), as a distinctive class of materials, have made great contributions to CO₂ capture and conversion. However, facile conversion of CO₂ to stable porous MOFs for CO₂ utilization remains unexplored. Herein, we present a facile methodology of using CO₂ to synthesize stable zirconium-based MOFs. Two zirconium-based MOFs CO₂-Zr-DEP and CO₂-Zr-DEDP with face-centered cubic topology were obtained via a sequential desilylation-carboxylation-coordination reaction. The MOFs exhibit excellent crystallinity, as verified through powder X-ray diffraction and high-resolution transmission electron microscopy analyses. They also have notable porosity with high surface area (S_BET up to 3688 m² g^-1) and good CO₂ adsorption capacity (up to 12.5 wt %). The resulting MOFs have abundant alkyne functional moieties, confirmed through ¹³C cross-polarization/magic angle spinning nuclear magnetic resonance and Fourier transform infrared spectra. Leveraging the catalytic prowess of Ag(I) in diverse CO₂-involved reactions, we incorporated Ag(I) into zirconium-based MOFs, capitalizing on their interactions with carbon-carbon π-bonds of alkynes, thereby forming a heterogeneous catalyst. This catalyst demonstrates outstanding efficiency in catalyzing the conversion of CO₂ and propargylic alcohols into cyclic carbonates, achieving >99% yield at room temperature and atmospheric pressure conditions. Thus, this work provides a dual CO₂ utilization strategy, encompassing the synthesis of CO₂-based MOFs (20-24 wt % from CO₂) and their subsequent application in CO₂ capture and conversion processes. This approach significantly enhances overall CO₂ utilization.