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Due to the high energy consumption in CO 2 capture by amine absorbents, CO 2 phase change absorbent, CPCA, has attracted a great attention in research institutes recently. Two phases are formed after CO 2 absorption with CPCA as the absorbent, and only the CO 2 -rich phase goes to the stripper, which could potentially reduce the energy consumption. In this work, the CPCAs composed of MEA/1-propanol/H 2 O were developed based on the principles of aqueous two-phase systems. The effects of temperature, amine concentration, and total CO 2 loading on the phase separation of CPCAs were studied. CO 2 loading and 1-propanol distributions in two phases under different experimental conditions were measured. The results indicated that the total CO 2 loading is the key factor affecting the distribution of components in two phases. Moreover, in comparison to traditional 30 wt % MEA, the initial absorption rates of all CPCAs were higher than that of MEA, and its maximum value was 5 times higher. The cyclic capacity of the CPCA with 30% MEA + 30% 1-propanol + 40% H 2 O was 1.70 mol/kg, which was 52% increased comparing to traditional 30 wt % MEA.

Development of CO2 phase change absorbents comprising MDEA/C4–C6 alcohol/H2O by means of the cosolvent effect.

Nonaqueous absorbents for CO2 capture have attracted great attention in research institutes recently because of their many advantages, such as energy efficiency and noncorrosiveness. Novel nonaqueous single-phase and biphasic absorbents have been developed. In this work, to satisfy application requirements, the effects of solvents on nonaqueous absorbents’ phase separation behavior and CO2 solubility were clarified. The nonaqueous absorbents comprising MEA and 26 kinds of solvents were investigated. The phase separation behavior after CO2 absorption, CO2 solubility, and CO2 cyclic capacity of nonaqueous absorbents were studied. The solvent polarity parameter E T(30) and the dielectric constant of solvents mainly affected the phase separation behavior and CO2 solubility of nonaqueous absorbents, respectively. The nonaqueous absorbent comprising a solvent with an E T(30) value larger than 50 kcal/mol maintained a single phase after CO2 absorption. The CO2 solubility of nonaqueous absorbents had a good positive relation with the dielectric constant of solvents. Moreover, nonaqueous absorbents comprising ethylene glycol monoethyl ether exhibited the optimal CO2 cyclic capacity and heat of CO2 absorption. In comparison to 30% MEA/H2O, the CO2 cyclic capacity of the nonaqueous absorbent increased by 51.8%, and the heat of CO2 absorption decreased by 35.4%.

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