The Transition States for CO₂ Capture by Substituted Ethanolamines

Abstract

Quantum chemical studies are used to understand the electronic and steric effects on the mechanisms of the reaction of substituted ethanolamines with CO2. SCS-MP2/6-311+G(2d,2p) calculations are used to obtain the activation energy barriers and reaction energies for both the carbamate and bicarbonate formation. Implicit solvent effects are included with the universal solvation model SMD. Carbamate formation is more favorable than bicarbonate formation for monoethanolamine (MEA) both kinetically and thermodynamically. Increase of the steric hindrance on the C atoms around the N atom in substituted ethanolamines favors bicarbonate formation over carbamate formation with lower activation barriers and thereby higher reaction rates. In contrast, substitution by an N-methyl or N-ethyl group on MEA leads to a lower activation barrier for both carbamate formation and bicarbonate formation. As a result, higher reaction rates are expected as compared to MEA, and therefore these compounds have significant potential as industrial CO2 capturing solvents.

Tuning the Carbon Dioxide Absorption in Amino Acid Ionic Liquids

“…[32][33][34][35][36][37] The formation of the zwitterionic carbamate occurs in the first step of the reaction sequence [Eq. (1) , and carbamic acids (RÀNHÀ COOH) at equilibrium.…”

“…[16] Apart from the energy barriers for the (amino acid anion)-CO 2 adducts, we also considered the intramolecular barrier of the proton transfer (Table S2) [a] The energies are given in the pure AAILs as depicted in Figure 2 b. ) and in several substituted ethanolamines (5-23 kJ mol À1 ) [37] indicate that inter- [31] and intramolecular [54] mechanisms are both important. Therefore, we recommend that both mechanisms are included in the training set if these systems are studied from a reactive force field.…”

Oxazolidine copper complexes: Synthesis, characterization and superoxide dismutase activity of copper(II) complexes with oxazolidine ligands derived from hydroxyquinoline carboxaldehyde

“…Serinol was used in the synthesis of some species of ceramides, acting as messengers for regulation and cellular apoptosis, an artificial nucleic acid and for DNA cleavage . Ethanolamine is widely used for adsorption and removal processes of carbon dioxide …”

CO2 capture in amine solutions: modelling and simulations with non-empirical methods

“…It is found either to happen via barrierless routes 27 or to imply activation barriers of values up to ∼13kcal/mol. 25,36 In Ref. Deprotonation of the zwitterion ((2b)-forward) in favor of another MEA acting as proton acceptor is the process most frequently investigated.…”

“…Beyond the great experimental effort aimed at this understanding, atomistic simulations and quantum-chemical calculations -started with the seminal papers by daSilva, Stevenson and collaborators 21,22 -have grown over the years. [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] By providing a critical survey of the recent computational studies, this paper is intended to contribute to clarify key questions related to the microscopic mechanisms accompanying the absorption of CO 2 . In particular, we shall concentrate on primary amines, and especially MEA and the uptake of CO 2 , which have been the focus of theoretical research, and examine to what extent the results depend on the model and method adopted.…”