Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

Ionic liquids (ILs) are promising solvents for carbon capture because of their high sorption capacity and low regeneration energy compared to conventional amine-based solvents. Previously, tetracyanoborate-based ILs have shown enhanced carbon dioxide (CO2) absorption capacity and absorption kinetics due to their low viscosity.1 In this work, the related IL 1-butyl-3-methylimidazolium tricyanomethanide ([bmim][tcm]) is studied for the first time as a solvent for CO2 capture. The physicochemical properties (e.g., density, viscosity, electrical conductivity, surface tension, thermal decomposition temperature, glass transition point) of pure [bmim][tcm] were experimentally determined and successfully described using appropriate correlations. [Bmim][tcm] was found to be a low-viscous IL with a relatively high thermal stability (Tdecomp = 473.15 K). The solubilities of CO2 in [bmim][tcm] were measured at temperatures ranging from (288.15 to 363.15) K and a pressure range of (0.01 to 10) MPa using two different methods (volumetric vs gravimetric), which show good agreement with each other. [Bmim][tcm] shows higher solubilities and therefore, higher sorption capacity compared to other nonfluorous ILs. The Peng Robinson equation of state was applied to correlate the experimental data. Henry s law constants (4 MPa to 13 MPa) and partial molar enthalpies of absorption (-14 kJ*mol 1) at different temperatures were also calculated from the measured solubility data. The diffusion coefficients of CO2 in [bmim][tcm] were determined at temperatures ranging from (308.15 to 353.15) K using the gravimetric method only. The diffusivity data of CO2 in [bmim][tcm] (~5*10 10 m2*s 1) are comparable to those in other low-viscous ILs, and show that high rates of absorption are possible. Therefore, it can be concluded that [bmim][tcm] is a promising candidate for carbon capture.