Novel Nonaqueous Liquid–Liquid Biphasic Solvent for Energy-Efficient Carbon Dioxide Capture with Low Corrosivity

Abstract

To address the problems of the relatively high energy penalty and corrosivity of aqueous biphasic solvents, a novel nonaqueous biphasic solvent composed of 2-((2-aminoethyl)­amino)­ethanol (AEEA), dimethyl sulfoxide (DMSO), and N,N,N′,N″,N″-pentamethyldiethylenetriamine (PMDETA) was proposed for CO2 capture. With optimization, this novel AEEA–DMSO–PMDETA (A–D–P) biphasic solvent could achieve a high CO2 loading of 1.75 mol·mol–1, of which 96.8% of the absorbed CO2 was enriched in the lower phase with only 49.6% of the total volume. 13C NMR analysis and quantum calculations revealed that A–D–P could absorb CO2 to form not only carbamate but also carbamic acid species, which were stabilized by DMSO via hydrogen-bonding interactions. Most products were highly polar and preferred to dissolve in polar DMSO rather than the less polar PMDETA, thus leading to the phase change. The thermodynamics results showed that the heat duty of A–D–P was only 1.66 GJ·ton–1 CO2 (393.15 K), which was significantly lower than that of the benchmark MEA (3.59 GJ·ton–1 CO2) and the reported aqueous biphasic solvents. Moreover, A–D–P presented a noncorrosive behavior to steel after CO2 saturation, clearly showing its superiority over MEA and the aqueous biphasic solvents. Therefore, with superior properties of energy savings and noncorrosiveness, the A–D–P biphasic solvent could be a promising candidate for CO2 capture.

Effect of Solvents on the Phase Separation Behavior and CO2 Capture Performance of MEA-Based Nonaqueous Absorbents

“…The phase separation behavior of nonaqueous absorbents was affected by the organic solvent polarity. Zhou et al 19 showed that the reaction products of amine with CO 2 were supposed to have high polarities and preferred to dissolve in a polar organic solvent. Yu et al 30 investigated the effects of the polarity and electronegativity of the N atom in tertiary amines on the phase separation behavior.…”

“…The advantages of phase change absorbents were used for reference, , and different kinds of nonaqueous biphase absorbents were reported. Novel nonaqueous liquid–liquid biphase absorbents comprising MEA-AMP-dimethyl sulfoxide (DMSO)- N , N , N ′, N ″, N ″-pentamethyldiethylenetriamine (PMDETA), and AEEA-DMSO-PMDETA were proposed. , Nonaqueous liquid–solid biphase absorbents comprising ethylenediamine (EDA)-ethanol, triethylenetetramine-PEG200, , potassium prolinate-ethanol, piperazine/ N , N -dimethylformamide (DMF), and EDA-DMF were investigated. Yet, to avoid solid formation and a nonlinear increase in viscosity, Chowdhury et al developed high-performance nonaqueous absorbents comprising alcohols that were in a single phase within the whole range of CO 2 loadings.…”

CO2 absorption and microwave regeneration with high‐concentration TETA nonaqueous absorbents

“…Studies have shown that increasing the concentration of MEA aqueous solution was expected to reduce the energy consumption of CO 2 capture 29,30 . At present, the concentration of nonaqueous absorbents used in most studies is less than 1 mol/L, especially polyamine absorbents with high absorption capacity 18,20,21,23,31,32 . This is relatively low compared with the concentration of MEA aqueous solution (5 mol/L) in practical industrial application, so the absorption–desorption behavior of non‐aqueous organic amine absorbents at high concentration still need to be studied.…”

“…Phase-change absorbents can significantly reduce the energy consumption in the regeneration step since only CO 2 -rich phases must be regenerated. For example, Zheng et al 20 and Tao et al 21,22 proposed two excellent liquid-solid phase-changing absorbents of TETA/ethanol and TETA/PEG200 by screening several amine/organic solvent combinations, and studied their CO 2 absorption and phase-changing behavior at 0.2-1 M. Zhou et al 23 developed a nonaqueous liquid-liquid phase-changing absorbent of 2-((2-aminoethyl)-amino)ethanol (AEEA)/dimethyl sulfoxide (DMSO)/pentamethyldiethylenetriamine (PMDETA), which had a CO 2 absorption capacity of 1.75 mol/mol AEEA at 1 M, and the rich phase contributed 96.8% of the CO 2 capacity.…”

“…29,30 At present, the concentration of nonaqueous absorbents used in most studies is less than 1 mol/L, especially polyamine absorbents with high absorption capacity. 18,20,21,23,31,32 This is relatively low compared with the concentration of MEA aqueous solution (5 mol/L) in practical industrial application, so the absorption-desorption behavior of non-aqueous organic amine absorbents at high concentration still need to be studied. Furthermore, flue gas impurities such as SO x , NO x , and water vapor have been proven to deactivate adsorbents during CO 2 capture, but there is still a lack of understanding of the effects on new absorbents.…”