Amidase‐Catalyzed Desorption of CO ₂ Captured in Aqueous Monoethanolamine (MEA) Solutions

Abstract

ABSTRACT Aqueous monoethanolamine (MEA) solutions can absorb CO 2 from industrial point sources via amine scrubbing. Mechanistically, CO 2 diffuses in and reacts with MEA or hydroxide to form a mixture of carbamate and carbonate/bicarbonate. Subsequently, CO 2 is released for storage or utilization via an energy‐intensive thermal solvent‐regeneration process. Here, we explored biocatalytic acceleration of the solvent regeneration step, which accounts for the dominant energy cost of carbon dioxide removal (CDR) processes. We conducted a sequence mining campaign based on urethane‐degrading Amidase Signature superfamily enzymes and discovered amidases that hydrolyze MEA carbamate, thereby increasing the overall release rate of CO 2 . The most promising candidate, an amidase from Parageobacillus caldoxylosilyticus (PcAmd), showed good thermostability ( T m around 70°C) and a specific activity against MEA carbamate of about 1 U/mg (20 nKat/mg). We found that PcAmd accelerated the regeneration of MEA sorbent. Specifically, PcAmd at 1 µM increased the initial CO 2 release rate by about 20%, and the time required to release 80% of the captured CO 2 was reduced by approximately half compared to enzyme‐free solutions. These results identified a novel potential of amidases in carbon capture and motivated further efforts to discover or engineer enzymes with better stability and activity for industrial CDR applications.