A nitrogen-rich organic polymer for CO2 utilization and conversion through cycloaddition of CO2 with epoxides

Abstract

The soaring levels of atmospheric carbon dioxide (CO₂), driven by fossil fuel consumption, pose significant environmental challenges, necessitating innovative strategies for its mitigation and utilization. This study introduces a novel, metal-free nitrogen-rich organic polymer, CMBr-OP, designed as an efficient catalyst for the cycloaddition of CO₂ with epoxides to produce cyclic carbonates. Synthesized through a straightforward one-step polymerization of cyanuric chloride and melamine, followed by functionalization with bromoacetic acid, CMBr-OP integrates multiple active sites, including nitrogen-rich triazine units and bromine functionalities, which synergistically enhance catalytic performance. Under mild reaction conditions (110°C, 1 MPa CO₂ pressure, 6 h), CMBr-OP achieves an impressive 99.6% yield of chloropropene carbonate without requiring co-catalysts or solvents. Comprehensive characterization techniques, including FTIR, XPS, SEM, and BET analysis, confirm its hierarchical porous structure, high surface area, and uniform distribution of active sites, facilitating efficient CO₂ activation and epoxide ring-opening. The catalyst demonstrates remarkable versatility, effectively catalyzing a wide range of epoxides, and exhibits excellent recyclability, maintaining high activity over five consecutive reaction cycles. DFT calculations reveal the critical role of hydrogen bond donors, nitrogen sites, and bromide ions in activating both epoxides and CO₂, underscoring the cooperative synergy within CMBr-OP. This work represents a significant advancement in sustainable catalytic systems for CO₂ utilization, aligning with green chemistry principles and offering a promising candidate for industrial-scale applications aimed at reducing CO₂ emissions and promoting environmentally friendly chemical processes.