Species distribution of CO2 absorption/desorption in aqueous and non-aqueous N-ethylmonoethanolamine solutions

• EMEA + ethanol solution had a much lower CO2 capacity than EMEA + H2O solution.
• EMEA + ethanol solution had a much higher EMEA regeneration efficiency than EMEA + H2O solution.
• The concentration of alky carbonate was lower than bicarbonate/carbonate.
• The existence of bicarbonate prevented the carbamate decomposing during desorption.

The CO2 absorption and desorption in N-ethylmonoethanolamine (EMEA) solutions were carried out using an absorption−desorption apparatus and the species distribution was explored using the quantitative 13C NMR spectroscopy. EMEA + ethanol solution had a much lower CO2 loading (0.547 mol CO2/mol EMEA) than EMEA + H2O solution (0.799 mol CO2/mol EMEA) due to the lower concentration of alky carbonate generated in EMEA + ethanol solution than the corresponding bicarbonate/carbonate as generated in EMEA + H2O solution and the no further reaction of carbamate with CO2 in EMEA + ethanol solution. The EMEA regeneration efficiency of the EMEA + ethanol solution at 363, 373 and 383 K (55.44, 86.86 and 100.00%) was much higher than EMEA + H2O solution at corresponding temperatures (27.56, 30.25 and 38.80%), which was mainly influenced by the decomposition of carbamate, while the existence of bicarbonate prevented carbamate decomposing.