Gas-Liquid Mass-Transfer Properties in CO2 Absorption System with Ionic Liquids

The deficiency of mass-transfer properties in ionic liquids (ILs) has become a bottleneck in developing the novel IL-based CO2 capture processes. In this study, the liquid-side mass-transfer coefficients (k(L)) were measured systematically in a stirred cell reactor by the decreasing pressure method at temperatures ranging from 303 to 323 K and over a wide range of IL concentrations from 0 to 100 wt %. Based on the data of kL, the kinetics of chemical absorption of CO2 with mixed solvents containing 30 wt % monoethanolamine (MEA) and 0-70 wt % ILs were investigated. The k(L) in IL systems is influenced not only by the viscosity but also the molecular structures of ILs. The enhancement factors and the reaction activation energy were quantified. Considering both the mass-transfer rates and the stability of IL in CO2 absorption system, the new IL-based system MEA + [bmim][NO3] + H2O is recommended. (C) 2014 American Institute of Chemical Engineers