Sustainable carbon capture, utilization, and sequestration (CCUS) reduces CO₂ emissions and is critical in accomplishing carbon neutrality targets. Here, we demonstrate new sustainable, solid-state, polyamine-appended, cyanuric acid-stabilized, melamine nanoporous networks (MNNs) via dynamic combinatorial chemistry (DCC) at the kilogram scale towards effective, scalable, recyclable, and high-capacity CO₂ capture. Our solid-state MNNs solve the long-standing problem of solvent degradation, equipment corrosion, and environmental leakage faced by traditional solvent methods with cheap solid raw materials (melamine and formaldehyde) through a facile synthesis method. Polyamine-appended MNNs reaction mechanisms with CO₂ were elucidated with double-level dynamic combinatorial chemistry. 2D heteronuclear chemical shift correlation (HETCOR) nuclear magnetic resonance (NMR) spectroscopy was performed to demonstrate the interatomic interactions between H and C atoms in the CO₂ reaction species at an atomic level. With quantitative NMR and density functional theory (DFT), we identified the reaction structure during CO₂ chemisorption, where ammonium carbamate pairs and a mix of ammonium carbamate and carbamic acid are easily distinguished. The coordination of polyamine and cyanuric acid modification endows the networks with high adsorption capacity (1.82 mmol/g at 1 bar), fast adsorption time (less than 1 min), low price ($40/ton), low regeneration energy (53 kJ/mol), and extraordinary stability to adsorption-desorption cycling by simulated flue gas. This work creates a general industrialization method towards sustainable CO₂ capture using networks (e.g., polymers, covalent organic frameworks, and metal-organic frameworks) via atomic-level and dynamic combinatorial chemistry design strategies with precise mechanism studies.

Haiyan Mao

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