A Novel Ionic Liquid for Carbon Capture

Many chemical processes require use of a solvent. Due to the adverse environmental effects of volatile organic compounds (VOCs), there is a need for replacement of traditional volatile solvents and hence a rising interest among researchers in the field of non-volatile solvents. A large number of chemical reactions are carried out in the presence of a solvent. Recently, a new class of non-volatile solvents has emerged called ionic liquids. An ionic liquid is an organic salt mainly composed of ions which are poorly coordinated, resulting in a low melting point often below 100°C. It consists of an organic or an inorganic bulky cation and a smaller anion. Due to the unsymmetrical ions, the lattice energy and the melting point of the ionic liquids are lower than of inorganic salts. Ionic liquids have many unique properties, such as high thermal stability, large oxidative and reductive range, good solvent for most of the organic and inorganic solutes, non-corrosive and corrosion-preventing nature, high ionic conductivity, and negligible vapour pressure. Their properties can be tailored, and hence ionic liquids have also been termed as the "designer solvents”. Ionic liquids can broadly be categorized into protic and aprotic ionic liquids. We have synthesized, and filed a patent on a new low-cost ammonium-based protic ionic liquid by solvent-free acid-base neutralization method. Its physicochemical properties like viscosity and density, and their variation with temperature have been measured, as well as its thermal stability quantified. Its application in carbon capture, considering its great affinity towards the CO2 molecules, has also been explored. Effect of interaction of water molecules with the ionic liquid on its absorption capacity for CO2 has also been assessed. It is found that this novel ionic liquid has the highest absorption capacity to cost ratio compared to all ionic liquids reported to date.