Understanding the mechanism of CO₂ capture by 1,3 di-substituted imidazolium acetate based ionic liquids

Abstract

Efficient CO2 capture by ionic liquids needs a thorough understanding of underlying mechanisms of the CO2 interaction with ionic liquids, especially when it involves chemisorption. In this work we have systematically investigated the mechanism of CO2 capture by 1,3 di-substituted imidazolium acetate ionic liquids using density functional theory. Solvent effects are analyzed using QM/MM and QM/QM approaches with the help of molecular dynamics simulations and ONIOM methods. The investigation of different stepwise mechanisms shows that CO2 could be involved in the first step of the reaction mechanism, also a new two-step mechanism is proposed. The final stabilization step is analyzed and pointed out to be responsible for important experimentally-observed features of the reaction.

A review of NMR methods used in the study of the structure and dynamics of ionic liquids

“…Ionic liquids (ILs) are low melting salts (mp < 100 °C) constituting mostly of an organic cation and an inorganic/organic anion . Because of their special properties such as the vapor pressure, wide liquid range, high thermal stability, and wide electrochemical stability, these are used in a varied range of applications starting from their use as a solvent in organic synthesis to their use as a MRI contrasting agent and even for CO2 capture applications . Besides this, ILs and its mixtures with lithium salts are used as an electrolytic media for various electrochemical devices such as in lithium battery, solar cells, and double layer supercapacitors .…”

Delineation of the Critical Parameters of Salt Catalysts in the N‐Formylation of Amines with CO2

“…[26,27] Hydrogen bonds play a key role in an umber of salt catalyzed CO 2 reactions such as the cycloaddition of CO 2 to epoxides, [28,29] which like the N-formylation reaction, is also predominantly driven by the anion. [26,27] Hydrogen bonds play a key role in an umber of salt catalyzed CO 2 reactions such as the cycloaddition of CO 2 to epoxides, [28,29] which like the N-formylation reaction, is also predominantly driven by the anion.…”

“…Interestingly,h igher yields are obtained for salts with benign (alkyl-functionalized) cations rather than [HOEMIm]Cl and [BMIm]Cl, which can interactw ith both the substrate and CO 2 by H-bonding or form N-heterocyclic carbenes (NHCs) following in situ C(2)-H deprotonation. [26,27] Hydrogen bonds play a key role in an umber of salt catalyzed CO 2 reactions such as the cycloaddition of CO 2 to epoxides, [28,29] which like the N-formylation reaction, is also predominantly driven by the anion. [30] In addition, NHCs were shown to be excellent catalysts for the N-formylation of amines with CO 2 and hydrosilanes.…”

NHC in Imidazolium Acetate Ionic Liquids: Actual or Potential Presence?

“…DFT and ONIOM calculations on imidazolium acetate-CO 2 system, both in the gas phase and in the liquid phase, considering the one-step and the two step mechanisms (Scheme 2, equations 1 and 2) allowed Damodaran and coworkers (Mao et al, 2016) to propose a new two-step reaction mechanism: at first the addition reaction between the imidazolium cation (at C2) and carbon dioxide, then the deprotonation of the C2-H of the adduct to yield NHC-CO 2 . The authors emphasize the important role played by IL in the stabilization of the products.…”