Tuning ionic liquid-based functional deep eutectic solvents and other functional mixtures for CO2 capture

Abstract

Ionic liquids (ILs) have several unique properties, including low vapor pressure, high thermal and chemical stability, high solubility, tunable structures and properties, etc. As carbon capture, utilization, and separation (CCUS) is one of the main strategies to reduce carbon emissions and deal with global climate change, IL-based functional deep eutectic solvents (DESs) and other mixtures with functional CO2-philic groups have been developed for efficient capture of CO2. This paper focuses on the research progress in the past five years (2017 ∼ 2022). The main contents include functional DESs based on IL salts (conventional IL salt + amine, conventional IL salt + HBD + superbase, functional IL salt + alcohol, functional IL salt + amine), and other functional mixtures based on ILs (conventional IL + amine, conventional IL + superbase, conventional IL-based ternary mixtures, functional IL + alcohol, functional IL + amine, functional IL + water, functional IL + alcohol + water, functional IL + amine + water, functional IL + amine + alcohol, functional IL + conventional IL). The absorption mechanisms of single or multiple carbamate and carbonate are discussed systematically. Finally, future directions and prospects for IL-based functional DESs and mixtures in CCUS are discussed. This review is benefit for researchers to obtain an overall understanding of CO2-philic functionalized DESs and other functional mixtures.