Reactive capture of CO<sub>2</sub> via amino acid.

Xiao, Yurou Celine; Sun, Siyu Sonia; Zhao, Yong; Miao, Rui Kai; Fan, Mengyang; Lee, Geonhui; Chen, Yuanjun; Gabardo, Christine M et al. · Nat Commun · 2024

basic_science · Level V

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Abstract

Reactive capture of carbon dioxide (CO<sub>2</sub>) offers an electrified pathway to produce renewable carbon monoxide (CO), which can then be upgraded into long-chain hydrocarbons and fuels. Previous reactive capture systems relied on hydroxide- or amine-based capture solutions. However, selectivity for CO remains low (<50%) for hydroxide-based systems and conventional amines are prone to oxygen (O<sub>2</sub>) degradation. Here, we develop a reactive capture strategy using potassium glycinate (K-GLY), an amino acid salt (AAS) capture solution applicable to O<sub>2</sub>-rich CO<sub>2</sub>-lean conditions. By employing a single-atom catalyst, engineering the capture solution, and elevating the operating temperature and pressure, we increase the availability of dissolved in-situ CO<sub>2</sub> and achieve CO production with 64% Faradaic efficiency (FE) at 50 mA cm<sup>-2</sup>. We report a measured CO energy efficiency (EE) of 31% and an energy intensity of 40 GJ t<sub>CO</sub><sup>-1</sup>, exceeding the best hydroxide- and amine-based reactive capture reports. The feasibility of the full reactive capture process is demonstrated with both simulated flue gas and direct air input.