A novel ionic liquids phase change absorption system for carbon dioxide capture and utilization

In order to achieve low cost, and reduce energy consumption during regeneration, a novel ionic liquid phase change absorbent composed of tetraethylenepentamine [TEPA] imidazole [Im] and diethylene glycol dimethyl ether (DGME) and water was designed for CO 2 capture applications. The absorbent [TEPAH][Im]+DM+H 2 O can achieves a CO 2 absorption capacity of 2.08 mol CO 2 /mol ILs, the rich phase volume accounts for 15.6 vol%, and the mass fraction of CO 2 is 99 %, this greatly reduces the regenerative volume of the absorption system, showing the potential of energy saving and emission reduction. After five absorption–desorption cycles, the regeneration efficiency of the system remained above 96 %. The CO 2 capture mechanism was analyzed using both 13 C NMR spectroscopy and density functional theory (DFT) calculations to elucidate its underlying processes. The cation [TEPAH] + and the anion [Im] - each undergo a reaction with CO 2 to produce carbamate, followed by hydrolysis of carbon dioxide to yield carbonate. The absorption system’s phase transition behavior primarily arises from variations in CO 2 product solubility across solvents. Moreover, the ionic liquid facilitated the conversion of CO 2 into quinazoline-2,4 (1H, 3H)-dione with a remarkable yield of 98 %. Even after five cycles, the ILs maintained substantial catalytic activity.