Scientific Approach for a Cleaner Environment Using Ionic Liquids

Ionic liquids (ILs) are ionic compounds composed of a bulky organic cation and a smaller anion. The size mismatch leads to the low melting points relative to typical ionic compounds such as NaCl. ILs have become a very fruitful area of academic and industrial research primarily because of their beneficial and diverse properties. Ionic liquids characteristically have low vapor pressures, good solvency, high ionic conductivities, and good heat transfer properties. Our work on different combinations of cations and anions has led to a wide span of properties, such as acidity, water solubility, chemical reactivity, viscosity, melting points, etc. Further optimization of a property for a particular application was accomplished through synthesis and compositional variations. Ionic liquid compositions can be tailored to make them much greener than many traditional solvents and catalysts. Volatile organic compounds (VOCs) may cause air pollution and health issues. As a result industrial processes are looking for solvents with decreased VOCs. Since ionic liquids are nonvolatile, they do not produce VOCs. These novel materials are used successfully for the removal of poisonous contaminants such as sulfur, nitrogen, Concarbon, and metals from traditional hydrocarbon feeds for fluid catalytic cracking and hydrocracking units. The design, synthesis, separation, and catalytic application of novel, green ionic liquids for making low sulfur, low nitrogen fuels, such as ultralow sulfur diesel, are discussed.