CO2 Capture in Ionic Liquids Based on Amino Acid Anions With Protic Side Chains: a Computational Assessment of Kinetically Efficient Reaction Mechanisms

Abstract

Absorption and capture of CO₂ directly from sources represents one of the major tools to reduce its emission in the troposphere. One of the possibilities is to incorporate CO₂ inside a liquid exploiting its propensity to react with amino groups to yield carbamic acid or carbamates. A particular class of ionic liquids, based on amino acids, appear to represent a possible efficient medium for CO₂ capture because, at difference with current industrial setups, they have the appeal of a biocompatible and environmentally benign solution. We have investigated, by means of highly accurate computations, the feasibility of the reaction that incorporates CO₂ in an amino acid anion with a protic side chain and ultimately transforms it into a carbamate derivative. Through an extensive exploration of the possible reaction mechanisms, we have found that different prototypes of amino acid anions present barrierless reaction mechanisms toward CO₂ absorption.

Keywords: CO2 storage; computational chemistry; green solvents; ionic liquids; protic side chains.