Bio-based organic polyamides as a non-metal heterogeneous catalyst for the halide-free cycloaddition of carbon dioxide

Abstract

Novel sustainable bio-based catalyst featuring superior advantages in CO 2 chemical conversion provides feasible schedule for alleviating the CO 2 excessive emission in the air. • A novel bio-based heterogeneous catalyst (MFM-KUST) was synthesized by a facile “one-pot” polycondensation at ambient temperature. • MFM-KUST exhibited higher catalytic performance in CO 2 cycloaddition than the melamine derivatives catalysts or other bio-based catalysts. • The CO 2 cycloaddition was carried out in the absence of metal, halide/co-catalyst and solvent reaction conditions. • MFM-KUST showed superior catalytic efficiency for the cycloaddition of CO 2 with epichlorohydrin, glycidol and propylene oxide, respectively. • The cycloaddition mechanism was proposed and verified based on experiment and DFT calculations. An environmentally-friendly organic polyamide heterogeneous catalyst (MFM-KUST) was prepared from bio-based nitrogen-rich precursors through a facile “one-pot” polycondensation at ambient temperature. MFM-KUST, a novel non-metal catalyst, was applied to the cycloaddition of CO 2 and epoxides into cyclic carbonates (maximum yield ∼98.8%) under halide- and solvent-free conditions. The chemical structures and properties of the catalysts prepared by different solvents were comprehensively evaluated by standard analytical techniques. The kinetics and cycle stability of MFM-KUST were investigated, in addition, the cycloaddition mechanism was proposed and verified based on experiment and density functional theory (DFT) calculations. The results showed that MFM-KUST had an excellent catalytic performance because of the synergistic effects between hydrogen bond donors (-N-H, C=O---H or =N---H), imino groups (-N=) of triazine-ring, and hydrazine group (N-H) with edge defects.