Harnessing Oxidized Amines as Robust Sorbents for Carbon Capture

Carbon capture and sequestration (CCS) is imperative to mitigating climate change1. Aqueous amine solutions are the leading technology for CO2 separations2, but they suffer from chemical instability under scrubbing conditions, corrosiveness, and toxicity, hindering their long-term deployment3–5. Herein, we demonstrate that tertiary amine N-oxides, an oxidative degradation product of amines6,7, can remove CO2 from dilute streams, including flue gas from a natural gas-fired power plant. Extensive spectroscopic and computational studies support that the non-toxic, non-corrosive, and inexpensive 4-methylmorpholine N-oxide (MMNO) captures CO2 under humid conditions via the formation of a hydrogen-bond-stabilized bicarbonate (HCO3−) species, despite being significantly less basic than an amine. MMNO exhibits improved oxidative and thermal stability compared to structurally similar amines, highlighting the potential of N-oxides to complement traditional amine-based scrubbers for industrial carbon capture applications.