A novel ILs biphasic absorbent with low regeneration energy consumption for CO2 capture: Screening of phase separation regulators and mechanism study

To achieve low regeneration energy consumption and low corrosion, a novel ILs nonaqueous biphasic absorbents composed of Tetraethylenepentamine (TEPA) Caprolactam (CPL), Ethylene glycol (EG), and Diethylene glycol dimethyl ether (DGDE) have been proposed for CO 2 capture. The maximum CO 2 loading of the optimal absorbent ([TEPAH][CPL]/EG/DGDE) could reach 1.88 mol·mol −1 , with 40 % of the saturated phase volume containing 98 % of the mass percentage of CO 2 products. Furthermore, the regeneration energy consumption was only 1.88 GJ·t −1 CO 2 , approximately 51 % lower than that of 30 wt% monoethanolamine (MEA) aqueous solution. 13 C NMR analysis has shown that the amino group on the cation [TEPAH] + reacted with CO 2 to form CO 2 products-carbamate, and the anion [CPL] - assisted the proton transfer during the reaction. Combined with the results from quantum chemical calculation, the phase separation behavior of the absorbent was mainly due to the polarity difference between the CO 2 products and the solvent. Additonally, [TEPAH][CPL]/EG/DGDE was non-corrosive to 20# carbon steel before and after CO 2 absorption, and exhibited superior stability than MEA aqueous solution.