Deep eutectic solvents based on cyclodextrin-monoethanolamine for high-efficiency carbon dioxide capture under high temperature

In this work, a new series of deep eutectic solvents (DESs) based on cyclodextrins (CDs) and monoethanolamine (MEA) was designed firstly for CO2 capture. The effects of CD type, molar ratio, temperature, water content, and CO2 concentration on the absorption ability were investigated. Among these DESs, the sample with the MEAamine:CDhydroxyl molar ratio of three (βCM3) shows excellent absorption property of CO2 under the wide range of temperature (30–110 °C). In particular, high absorption capacity and rate (28.72 wt%, 1 h) is achieved under 80 °C. Meanwhile, cycling performance remains above 90% after 23 time cycles. The hydrogen bond structure and CO2 capture mechanism were demonstrated using FT-IR, NMR and DFT calculation. The circular hydrogen bond composed with hydroxyl of MEA and CD makes DESs more stable. The increase of activation energy of zwitterion intermediate and the decrease of stability of carbamate guarantee the DESs effective absorption CO2 and regeneration. This study provides the experimental and theoretical guidance for potential industrial applications of CO2 capture with novel DESs.