Distillable Protic Ionic Liquid 2‑(Hydroxy)ethylammonium Acetate (2-HEAA): Density, Vapor Pressure, Vapor–Liquid Equilibrium, and Solid–Liquid Equilibrium

Abstract

Recently it has been found that certain ionic liquids (ILs) have notable vapor pressures (Earle et al. <i>Nature</i> <b>2006</b>, <i>439</i>, 831–834). These ILs may be important in various novel technologies, but they may also be important in postcombustion carbon captures as side products. In this work a distillable protic ionic liquid (PIL) 2-(hydroxy)­ethylammonium acetate (2-HEAA) was prepared from monoethanolamine (MEA) and acetic acid (HAc) and it was purified with a Vigreaux type distillation column under vacuum. Density was measured for the MEA + 2-HEAA and HAc + 2-HEAA systems with a DMA HP densimeter from 293 to 363 K. The Redlich–Kister polynomial was used to model the density data. Vapor–liquid equilibrium was measured for the H₂O + HAc + 2-HEAA system with a static total pressure apparatus at 347 K. Solid–liquid equilibrium was measured for the H₂O + HAc + 2-HEAA system with a visual method. The NRTL activity coefficient model was used to model the vapor–liquid and solid–liquid equilibrium data