Phase Splitting Agent Regulated Biphasic Solvent for Efficient CO₂ Capture with a Low Heat Duty

Abstract

A biphasic solvent features high absorption capacity and low heat duty for CO 2 capture. Phase separation behavior is essential to cut down energy penalty. Four phase splitting agents with different hydrophobicities, such as 1,3-dimethyl-2-imidazolidinone (DMI), 1-methyl-2-pyrrolidinone (NMP), N,N-dimethylformamide, and sulfolane, were dosed to biphasic solvents, triethylenetetramine and 2-(diethylamino)ethanol. Experimental results revealed that they can tune the phase separation behavior during CO 2 absorption. Generally, under the same CO 2 loading, the volume ratio of the rich phase increased with their hydrophobicity (log P), which accounts for over 50%. Moreover, their influences on absorption capacity, kinetics, and thermodynamics were also investigated. After dosing NMP, the heat duty was decreased by 22%. Furthermore, a phase splitting agent with a positive log P was more conducive to reducing the heat duty, and one with a negative log P enhanced the absorption rate. With DMI, the absorption rate was 114% higher than that of MEA at rich loading. The 13 C NMR analysis showed that the agents were not involved in CO 2 absorption and did not affect the reaction mechanism. Furthermore, quantum calculation was used to verify the reaction mechanism, confirming that the phase splitting agent increases the reaction equilibrium constant and makes it proceed more thoroughly.

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

“…Based on the above problems existing in the research of nonaqueous absorbents, in this work, we studied the absorption behavior of high‐concentration TETA in three typical organic solvent absorbents, including polyethylene glycol 200 (PEG200), diethylene glycol (DEG), and ethylene glycol (EG). TETA was used considering its high absorption capacity, relatively low vapor pressure than MEA, and high regeneration efficiency as demonstrated in the studies 21,28,36–38 . And the performance of MEA aqueous solution was compared.…”

“…TETA was used considering its high absorption capacity, relatively low vapor pressure than MEA, and high regeneration efficiency as demonstrated in the studies. 21,28,[36][37][38] And the performance of MEA aqueous solution was compared. In addition, the microwave heating was used to study the regeneration performance of TETA absorbents, and the properties of microwave heating regeneration with high concentration nonaqueous absorbents were explored.…”

Low-Energy-Consumption CO2 Capture by Liquid–Solid Phase Change Absorption Using Water-Lean Blends of Amino Acid Salts and 2-Alkoxyethanols

“…Several advance technologies have been recently proposed, including catalyzed solvents, including enzymes or solid acids, , microencapsulated liquid solvents, polarity-swing-assisted solvents, phase change solvents, − and ionic liquids . Among these, phase change absorbents have recently gained particular attention .…”

“…Several advance technologies have been recently proposed, including catalyzed solvents, including enzymes or solid acids, , microencapsulated liquid solvents, polarity-swing-assisted solvents, phase change solvents, − and ionic liquids . Among these, phase change absorbents have recently gained particular attention . Since a homogeneous solution can undergo a phase transition into a biphasic system during CO 2 absorption and the absorbed CO 2 can be concentrated into one phase, it should have potential to significantly reduce energy consumption by regenerating only the CO 2 -rich phase.…”

“…16 Among these, phase change absorbents have recently gained particular attention. 14 Since a homogeneous solution can undergo a phase transition into a biphasic system during CO 2 absorption and the absorbed CO 2 can be concentrated into one phase, it should have potential to significantly reduce energy consumption by regenerating only the CO 2 -rich phase.…”