Supramolecular chemistry for more efficient CO2 capture

One of the techniques for trapping CO₂ involves the use of amines, nitrogen-containing organic molecules with which this gas easily binds. Chemists at CNRS have demonstrated that when these amines are enclosed in a cage molecule (which can encapsulate other molecules) through supramolecular chemistry, the gas capture becomes much more efficient. These results can be found in the Journal of the American Chemical Society.


Among the various technologies aimed at capturing gaseous CO₂, one of the most efficient techniques uses amines, a family of nitrogen-containing organic molecules with which this greenhouse gas reacts readily. Two reaction products are formed in parallel: ammonium carbonates, compounds that have a wide range of domestic and industrial applications in the food industry (acidity regulator, leavening agent...), and ammonium carbamates, a source of ammonia widely used in industry and involved in the synthesis of urea, which is massively used as a fertilizer.


However, the large-scale deployment of this technology is hindered by overly high energy implementation costs. Hence the necessity to find new amine formulations capable of capturing larger amounts of carbon dioxide at the same or even lower energy cost.

In this context, chemists from the Institute of Molecular and Supramolecular Chemistry and Biochemistry (CNRS/University Claude Bernard Lyon 1) have shown that the formation of supramolecular complexes between a cage-forming organic molecule and polyamines shifts the CO₂ capture equilibria in water towards the almost exclusive formation of ammonium carbonates, leading to a significantly greater amount of CO₂ trapped per polyamine. They analyze the reactions in terms of the energy involved in these equilibrium shifts that include both covalent and non-covalent bonds.

Beyond the new fundamental insights, this study emphasizes the potential role supramolecular chemistry could play in this major environmental challenge.

Writer: CCdM

Reference:
T. Chetot, F. Marocco Stuardi, A. Forot, M. Ducreux, A. Baudouin, E. Chefdeville, F. Perret, L. Vial, J. Leclaire.
Switching between Non-isoenergetic Dynamic Covalent Reactions using Host-guest Chemistry
J. Am. Chem. Soc. 2024
doi.org/10.1021/jacs.4c03400