Experimental and Theoretical Insights into CO2 and N2 Capture Using Natural Hydrophobic Deep Eutectic Solvents at High Pressures.

This study explores three binary natural hydrophobic deep eutectic solvents (HDESs) for capturing carbon dioxide (CO2) and nitrogen (N2) at high pressures. The HDES systems, comprising linoleic acid (LnA) as a hydrogen-bond donor (HBD) and camphor (CAM), citral (CIT), or piperitone (PIP) as a hydrogen-bond acceptor (HBA), were synthesized and characterized for density, viscosity, conductivity, surface tension, and contact angle. High-pressure gas absorption experiments demonstrated CO2 and N2 capture, achieving absorption rates of ∼62%-92% within 100 s at 10-30 bar. At 25 bar, a mole fraction absorption of 0.47 matched the performance of aqueous monoethanolamine (MEA) at 25 °C. Among the HDESs, CAM-LnA (1:1) exhibited the highest CO2 selectivity at 2.5 and 5 bar, with values of 41.4 and 44.2, respectively. The conductor-like screening model for real solvents (COSMO-RSs) method predicted eutectic points and gas absorption, while molecular dynamics simulations assessed gas interactions at the molecular level. The results underscore the potential of HDES for high-pressure gas capture, providing insights into their production, characterization, and applications.