Tuning basic poly(ionic liquid) solutions towards atmospheric pressure CO₂ capture

Highlights

• PIL solutions present higher CO₂ sorption capacity compared to IL solutions.

• The design of soluble PILs is an interesting alternative to reduce viscosity limitations.

• PIL solutions can capture CO₂ taking advantage of water sorption [HCO₃]^-/[CO₃]^2-and physisorption.

• Acetate-based PILs solutions present higher performance towards CO₂ sorption.

Abstract

Ionic liquids and poly(ionic liquid)s are interesting materials for CO₂ capture, however, the deployment of their industrial application has been delayed on account of economic and technical issues that demand further optimization. The control over viscosity has serious consequences over the process, therefore, this work is focused on the study of imidazolium and pyrrolidinium-derived ILs and PILs with basic anions, such as acetate, hydroxide, and imidazolate that were synthesized and characterized by NMR, ATR-FTIR, TGA, and DSC. Different solvents and concentrations were tested in the preparation of PIL and IL solutions, which were used to capture CO₂ by bubbling this gas at room temperature and atmospheric pressure (1 atm). The evaluation of the CO₂ sorption capacity of each sample was carried out through the analysis of quantitative ¹³C NMR. The poly(1-vinyl-3-ethylimidazolium) acetate showed and sorption capacity of 5.68 mmol CO₂/g PIL, and also the capacity to capture CO₂ from exhaust gas mixture and the possibility to be recycled at least 5 times.