Experimental solubility of carbon dioxide in monoethanolamine, or diethanolamine or N-methyldiethanolamine (30 wt%) dissolved in deep eutectic solvent (choline chloride and ethylene glycol solution)

Abstract

The success achieved by the COP21 in Paris in 2015 by committing 195 states to reduce the temperature of the planet, shows that it is urgent to find a solution to greenhouse gas emissions especially the CO2. Monoethanolamine (MEA) in aqueous solution is the reference solvent to capture CO2 emission based on chemical absorption. However, aqueous solutions present some drawbacks, such as equipment corrosion, loss of solvent and high energy consumption. New and green solvents could be a possible solution to this issue.As part of this study, new experimental data on the solubility of carbon dioxide in monoethanolamine, MEA or diethanolamine DEA or methyldiethanolamine MDEA 30 wt%, dissolved in greener and nontoxic deep eutectic solvent (DES) made of choline chloride (ChCl) and ethylene glycol (EG) with a molar ratio of 1:2 are reported. Measurements were performed at three different temperatures; 298.1, 313.1 and 333.1 K and pressures from 2 Pa up to 800 kPa using astatic apparatus with on-line analysis of the gas phase by GC to determine the partial pressure of CO2. The dissolved CO2 in the liquid was determined by volumetric method. In a first step, the apparatus and the entire CO2 isotherm determination protocol were validated by the study of CO2 absorption in aqueous solution of MEA (reference amine). As no literature data was available, the solubilities of CO2 in the DES/amine were compared with those obtained from the aqueous media. The two set of measurements are very close.Gabrielsen et al. (2005) model of correlation based on the equilibrium constant, initially used for aqueous amine solutions, has been successfully extended to CO2 capture by nonaqueous solutions.Comparison of heat of absorption values between aqueous amines and in the DES was also investigated.To the best of our knowledge, this is the first time CO2 isotherms of three classes of amine dissolved in the DES (choline chloride/ethylene glycol) was studied.