Study on regeneration characteristics of choline chloride-monoethanolamine deep eutectic solvent after capturing CO₂ from biogas

Choline chloride-monoethanolamine deep eutectic solvent (ChCl-MEA DES) can deeply remove CO2 from biogas. This study focused on regeneration of ChCl-MEA DES after CO2 capture. The effects of regeneration temperature, time and water content on CO2 absorption capacity, absorption rate and CO2/CH4 absorption selectivity after regeneration were evaluated. The addition of HZSM-5 catalyst during regeneration further promoted regener-ation efficiency. FTIR and NMR indicated that carbamates were formed after absorption, and water made it easier for the amino group to react with CO2 to form carbamates. The highest regeneration percentage of absorbent was up to 99.89%, and the CO2 absorption capacity even didn't decrease significantly after 8 cycles. The ideal regeneration energy consumption in the experiment was also evaluated. This research provided a valuable reference for the application of this absorbent in CO2 purification of biogas.