Solvation of Carbon Dioxide in [C₄mim][BF₄] and [C₄mim][PF₆] Ionic Liquids Revealed by High‐Pressure NMR Spectroscopy

Abstract

Where is CO2 ? The intermolecular interactions of [C4 mim]BF4 and [C4 mim]PF6 ionic liquids and CO2 have been determined by high-pressure NMR spectroscopy in combination with molecular dynamic simulations. The anion and the cation are both engaged in interactions with CO2 . A detailed picture of CO2 solvation in these ILs is provided. CO2 solubility is essentially determined by the microscopic structure of the IL.

Imidazolium Salt Ion Pairs in Solution

“…In ILs, site-specific NOE may reflect the mean orientation of the ions over longer distances rather than the local structure of distinct ion aggregates. [59] To account for the long-range effects and avoid over interpretations in terms of local structure, it is important to focus on the changes in the NOE induced by the presence of organic solvents.…”

Structurally simple complexes of CO2

“…In these cases, especially for imidazolium-based ILs, weak cation-anion interactions and hydrogen bonds are often invoked to explain the observed solubility. 115,116 Beyond the realm of simple capture-and-release applications of carbon dioxide, bending/activating carbon dioxide for its use as a chemical feedstock is required. This leads to the other end of the spectrum, i.e.…”

Carbon Dioxide Capture by Aqueous Ionic Liquid Solutions

“…Therefore, the search for new alternatives either for pre-or post-combustion CO 2 capturer emains ac hallenge. [12] CO 2 does not competew ith the anion for the same locations about the cation as it establishes weaker interactions. [6] In particular, ILs are amongt he mosti nvestigated fluids for the reversible sequestration of CO 2 .…”