Reversible Carbon Dioxide Capture at High Temperatures by Tetraethylenepentamine Acetic Acid and Polyethylene Glycol Mixtures with High Capacity and Low Viscosity

Abstract

Ionic liquids (ILs) are investigated in many studies to capture CO 2 in recent years.However, almost all of these studies carried out the absorption of CO 2 by ILs at relatively low temperatures (lower than 333.15K or even around the room temperature). Besides, the viscosity of ILs increases dramatically after absorbing CO 2 which could reduce the absorption efficiency significantly. Reversible and efficient absorption of CO 2 at high temperatures was investigated by IL of tetraethylenepentamine acetic acid ([TEPA]Ac) and polyethylene glycol 200 (PEG-200) mixtures with low viscosity. The results showed that the absorption capacity of [TEPA]Ac/PEG-200 mixtures achieved to 1.24 mol CO 2 per mole [TEPA]Ac at 353.15 K at ambient pressure (1.01 bar). The mixtures could be easily regenerated by bubbling dried N 2 through them. The addition of PEG-200 in the [TEPA]Ac could increase the efficiency of absorption and desorption significantly. Furthermore, the solubility data of CO 2 in the [TEPA]Ac/PEG-200 mixtures at T = (353.15, 368.15, 383.15, and 398.15) K under different pressures were measured and the solution enthalpy (∆H sol ) and solution entropy (∆S sol ) were calculated. Under all the conditions, the negative value of ∆H sol indicated that the capture process is exothermic. The process of CO 2 capture described that using [TEPA]Ac/PEG-200 mixtures is a promising approach for CO 2 absorption with high reversibility and excellent absorption property at a relatively high temperature.

A Novel Phase-Changing Nonaqueous Solution for CO2 Capture with High Capacity, Thermostability, and Regeneration Efficiency

“…11−13 Moreover, PEGs are inexpensive and have lower viscosity than ILs. 14 Some studies indicate that CO 2 also exhibits high solubility in PEGs due to the quadrupole interaction of CO 2 with polar ether oxy-gens. 15−17 Hence, some researchers use PEGs as a cosolvent for ILs to decrease the viscosity of ILs after CO 2 absorption.…”

“…Hui and Yang 18 reported that ILs of diethylenetriamine hydrobromide ([DETAH]Br) dissolved in PEG200 have a CO 2 absorption capacity of 1.184 mol/mol [DETAH]Br and a regeneration efficiency of 86.67% after five consecutive cycles. Similarly, Yu et al 14 investigated the CO 2 absorption by ILs of tetraethylenepentamine acetic acid ([TEPA]Ac) and PEG200 mixtures, and results show that the absorption capacity can reach 1.24 mol/mol [TEPA]Ac at 353.15 K. Some researchers have also tried using PEGs only as the solvent for primary or secondary amines. Li and co-workers 7 studied the PEG200 solution of diglycolamine (DGA) or MEA for CO 2 absorption, respectively.…”

“…Several types of organic solvents can be used in the solutions, which include ethylene glycol, diethylene glycol, and triethylene glycol. Thereinto, poly­(ethylene glycol) (PEG) is an environmentally benign solvent with some appealing properties similar to ionic liquids (ILs), such as low toxicities, good chemical and thermal stability, and negligible vapor pressure. − Moreover, PEGs are inexpensive and have lower viscosity than ILs . Some studies indicate that CO 2 also exhibits high solubility in PEGs due to the quadrupole interaction of CO 2 with polar ether oxygens. − Hence, some researchers use PEGs as a cosolvent for ILs to decrease the viscosity of ILs after CO 2 absorption.…”

“…Hui and Yang reported that ILs of diethylenetriamine hydrobromide ([DETAH]­Br) dissolved in PEG200 have a CO 2 absorption capacity of 1.184 mol/mol [DETAH]Br and a regeneration efficiency of 86.67% after five consecutive cycles. Similarly, Yu et al investigated the CO 2 absorption by ILs of tetraethylenepentamine acetic acid ([TEPA]­Ac) and PEG200 mixtures, and results show that the absorption capacity can reach 1.24 mol/mol [TEPA]Ac at 353.15 K.…”

Effects of Poly(glycidyl ether) Structure and Ether Oxygen Placement on CO2 Solubility

“…Poly­(ethylene oxide) (PEO) has been used for CO 2 separations as a liquid absorbent since the 1960s and was first applied in membrane applications in the late 1980s. , Favorable quadrupolar interactions between the ether oxygens in the polymer backbone and dissolved CO 2 result in high solubility and permeability. − Currently, PEO is used in two major industrial separations: (1) as the main component of Selexol, an industrial acid gas absorbent, and (2) the Polaris membrane, which is the first commercial membrane used for CO 2 separation. , In the 50 years of the Selexol process, research interest in PEO for CO 2 separation has not declined. PEO has been cross-linked to make free-standing membranes ,, and has been incorporated as a membrane additive , or the soft-segment of block copolymer membranes to increase solubility. , PEO has also been used as a nonaqueous cosolvent for amine and ionic liquid (IL) solutions to increase regeneration efficiency and reduce corrosion, energy consumption, and viscosity. − …”