Mixed solvent of alcohol and protic ionic liquids for CO capture: Solvent screening and experimental studies

Using ionic liquids to capture CO to produce high-purity hydrogen (H2) is a promising method. However, there is a lack of theoretical screening for CO capture, which can reduce the number of experiments and costs. In addition, ionic liquids need to reduce their viscosity and maintain an excellent CO capture effect. Therefore, The COSMO-RS was used to screen 300 ionic liquids using CO/H2 selectivity and viscosity at 293.15 K as indicators. The results showed that the target ionic liquid screened was [EimH][CuCl2]. The addition of ethylene glycol (EG) reduced the viscosity of [EimH][CuCl2] and improved the CO capture ability. After adding 25 wt% EG, its separation factor of CO/H2 could reach 180 at 293.15 K and 2.1 MPa, which was 59% higher compared to the pure ionic liquid. Furthermore, EG inhibits foaming, and the mixed solvent could maintain high stability after recycling.