Carboxylate‐Assisted Formation of Alkylcarbonate Species from CO₂ and Tetramethylammonium Salts with a β‐Amino Acid Anion

Abstract

Tetramethylammonium-based molten salts bearing a β-amino acid anion (TMAAs) are synthesized through Michael addition reactions of amines with methyl acrylate followed by hydrolysis and subsequent neutralization by using aqueous tetramethylammonium hydroxide. The CO(2) capture performances of the TMAAs are evaluated and are shown to interact with CO(2) in a 1:1 mode in both water and alcohol. FTIR and (13)C NMR spectroscopic studies on the interactions of TMAAs with CO(2) indicate that the type of CO(2) adduct varies with the solvent used. When water is used as the solvent, a bicarbonate species is produced, whereas hydroxyethylcarbonate and methylcarbonate species are generated in ethylene glycol and methanol, respectively. Computational calculations show that the carboxylate groups of TMAAs contribute towards the formation and stabilization of 1:1 CO(2) adducts through hydrogen bonding interactions with the hydrogen atoms of the amino groups.

Water-Lean Solvents for Post-Combustion CO2Capture: Fundamentals, Uncertainties, Opportunities, and Outlook

“…Following this work, Kim et al reported a 1:1 CO 2 capture stoichiometry using tetramethylammoniumbased amino acid (TMAA) salts via the formation of alkyl carbonate (Figure 13). 61 In this system, the amino acid salt enables the reaction of alcohol with CO 2 by facilitating the deprotonation and also stabilization of the incipient alkyl carbonate. Similar transformations will be presented in the section on CO 2 BOLs, in which a strong base such as a guanidine combines with alcohols to produce alkylcarbonates.…”

CO2 Absorption and Desorption in an Aqueous Solution of Heavily Hindered Alkanolamine: Structural Elucidation of CO2-Containing Species

“…9,10 In order to circumvent the problems associated with the use of aqueous alkanolamines, a variety of CO 2 capture solvent systems have been developed, which are based on superbases, 11−14 phase changing silicon compounds, 15,16 diamines, 10,17,18 cyclic amines, [12][13][14]19 lipophilic amines, 17,20 and amino acid. 21,22 The modification of MEA by introducing a functional group or groups has also been attempted to improve the absorption and desorption performance of MEA. 10,23−25 While the advances with these alternative CO 2 capture systems are significant, there still remain many obstacles to overcome for their practical application, especially in terms of absorption rate, cost of capture media, and processability.…”

“…In order to circumvent the problems associated with the use of aqueous alkanolamines, a variety of CO 2 capture solvent systems have been developed, which are based on superbases, − phase changing silicon compounds, , diamines, ,, cyclic amines, − , lipophilic amines, , and amino acid. , The modification of MEA by introducing a functional group or groups has also been attempted to improve the absorption and desorption performance of MEA. ,− While the advances with these alternative CO 2 capture systems are significant, there still remain many obstacles to overcome for their practical application, especially in terms of absorption rate, cost of capture media, and processability. Accordingly, tremendous efforts have been devoted to develop high performance alkanolamine-based CO 2 capture solvents with low regeneration energy and high absorption capacities and rates, and as a result, considerable amounts of kinetic, thermodynamic, and spectroscopic data have been accumulated on the CO 2 absorption in alkanolamines. ,,− Nonetheless, the understanding of the nature of CO 2 -containing species involved is still primitive due to the lack of unambiguous evidence on the types of amine-CO 2 salts formed during absorption and regeneration, especially for hindered amines …”

Ammonium-, phosphonium- and sulfonium-based 2-cyanopyrrolidine ionic liquids for carbon dioxide fixation

“…In turn, Kim and coworkers reported equimolar CO 2 absorption capacities of the primary and secondary amino-functionalized RTILs. 56 The investigation of three dual-functionalized ILs, combining diethylenetriamine cation with AHA for efficient and reversible CO 2 capture, was presented by Wu et al 54 The protonation of AHA during the CO 2 absorption process is reported to help the recycling of the active components of the absorbent and thus to enhance its renewability. By significantly improving CO 2 absorption capacity, [57][58][59] they simultaneously increase the viscosity of the liquid.…”