Experimental study on solubility of CO2 and CH4 in the ionic liquid 1-benzyl-3-methylimidazolium nitrate

The solubility of two single gases, CO2 and CH4, was measured in the ionic liquid 1-benzyl-3-methylimidazolium nitrate ([Bzmim][NO3]), at temperatures ranging from 298.15 to 343.15 K and pressures up to 4.52 MPa for CO2 and 4.22 MPa for CH4, where the CO2 and CH4 mole fractions reached to 0.29 and 0.09, respectively. The solubility measurements were performed in a stainless steel equilibrium cell. Under the experimental conditions, CO2 showed a significantly higher solubility than CH4. The CO2 solubility decreased in [Bzmim][NO3], when temperature was raised, while in the case of CH4, the solubility increased slightly with the increase of temperature. In addition, the CO2 solubility was compared to that of CH4 using the ratio of the Henry’s constants of CH4 over that of CO2. The changes in ideal selectivity vs temperature showed that by the increase in temperature the ideal selectivity decreases.