Ionic Liquids Hybridization for Carbon Dioxide Capture: A Review

CO₂ absorption has been driven by the need for efficient and environmentally sustainable CO₂ capture technologies. The development in the synthesis of ionic liquids (ILs) has attracted immense attention due to the possibility of obtaining compounds with designated properties. This allows ILs to be used in various applications including, but not limited to, biomass pretreatment, catalysis, additive in lubricants and dye-sensitive solar cell (DSSC). The utilization of ILs to capture carbon dioxide (CO₂) is one of the most well-known processes in an effort to improve the quality of natural gas and to reduce the green gases emission. One of the key advantages of ILs relies on their low vapor pressure and high thermal stability properties. Unlike any other traditional solvents, ILs exhibit high solubility and selectivity towards CO₂. Frequently studied ILs for CO₂ absorption include imidazolium-based ILs such as [HMIM][Tf₂N] and [BMIM][OAc], as well as ILs containing amine groups such as [Cho][Gly] and [C₁ImPA][Gly]. Though ILs are being considered as alternative solvents for CO₂ capture, their full potential is limited by their main drawback, namely, high viscosity. Therefore, the hybridization of ILs has been introduced as a means of optimizing the performance of ILs, given their promising potential in capturing CO₂. The resulting hybrid materials are expected to exhibit various ranges of chemical and physical characteristics. This review presents the works on the hybridization of ILs with numerous materials including activated carbon (AC), cellulose, metal-organic framework (MOF) and commercial amines. The primary focus of this review is to present the latest innovative solutions aimed at tackling the challenges associated with IL viscosity and to explore the influences of ILs hybridization toward CO₂ capture. In addition, the development and performance of ILs for CO₂ capture were explored and discussed. Lastly, the challenges in ILs hybridization were also being addressed.