Dual-functionalized ionic liquid biphasic solvents with aqueous-lean for industrial carbon capture: Energy-saving and high efficiency

A novel, sustainable, dual-functionalized amino ionic liquid biphasic solvent of 3-(Dimethylamino)-1-propylamine-1,2,4-triazole/poly (ethylene glycol) dimethyl ether/water ([DMAPA][TZ]/NHD/water) was proposed for CO2 capture to reduce the consumption of regeneration energy. Experimental results showed that the CO2 absorption loading of the solvent was 1.95 mol CO2·L−1 solvent at a CO2 partial pressure of 15 kPa. The volume of the CO2-rich phase was 40 vol% of the total volume, with a loading of up to 4.65 mol CO2·L−1 solvent, accounting for approximately 95.4% of the blended CO2 loading in the solvent. The CO2-rich phase could be regenerated by 92.3% in 10 min at 373 K, without the presence of a lean phase. The regeneration efficiency of the solvent was maintained at 83% after 10 adsorption and desorption cycles. The reaction, regeneration, and phase-change mechanism were investigated using 13C NMR and phase composition analysis. CO2 reacted with [DMAPA][TZ] to form two kinds of carbamate during solubilization, and all carbamates could be further hydrolyzed to form HCO3− and CO32−. The solvent effect, phase-change behavior, and CO2 physical dissolution of NHD could promote the absorption and desorption rate and absorption capacity of CO2. The energy consumption for CO2 desorption could be reduced to 1.335 GJ·t−1 CO2, which was 67% lower than that of 30 wt% ethanolamine (3.99 GJ·t−1 CO2), given the lower heat of reaction, specific heat capacity, and solvent loss. Thus, this solvent presents a sustainable strategy for advancing carbon capture technologies.