Handling CO₂ Sorption Mechanism in PIL@IL Composites.

Abstract

The mitigation of climate change effects requires the use of alternative materials and technologies to control CO₂ atmospheric levels through its capture, storage and use. In this field, the current work presents the evaluation of two poly(ionic liquid)s (PILs) (poly-1-vinyl-3-ethylimidazolium acetate and hydroxide) combined with free ionic liquid (IL) 1-butyl-3-methylimidolium acetate (BMI·OAc) for CO₂ capture. The sorption capacity of PIL@IL composites was evaluated under 20 bar of CO₂ at 298 K. Nuclear Magnetic Resonance (NMR) spectroscopy allowed quantification of CO₂ sorption (physisorption and/or chemisorption) and in situ study of the PIL−CO₂ interaction mechanism. NMR in combination with Molecular Dynamics (MD) simulations suggested a 3D organization of PIL composites, maintaining a similar organization to ILs. Also, the use of aqueous solutions of PIL@IL composites was tested, identifying the optimum conditions for water activation (intrinsic water trapped inside IL structure) for chemisorption. As our main contribution, we demonstrate the possibility to control the sorption pathway towards CO₂ physisorption, or CO₂ conversion (chemisorption) through carbonation (HCO₃^-/CO₃^2-) according to the PIL/IL ratio, ions structure and water amount. The use of PIL/IL composites is a promising advance for further CO₂ reuse approaching a biomimetic carbonation process.

 

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