Density, viscosity, and H2S solubility of N-butylmorpholine bromide iron-based ionic liquids

The density and viscosity of N-butylmorpholine bromide iron-based ionic liquids ( r FeCl 3 / [Nbmm]Br) with two iron-morpholine ratios ( r  = 0.8 and 1.0) mol·mol −1 were measured at 303.15–348.15 K and 101.3 kPa. Density and viscosity data were fitted by empirical correlations for temperature. The average relative errors were less than 0.02 % and 2 %, respectively. The density and viscosity decrease with increasing temperature. The density increases with the increase of r , while the viscosity shows the opposite trend. The gas-liquid equilibrium data of H 2 S in r FeCl 3 /[Nbmm]Br were measured by the isochoric pressure drop method at temperatures of 303.15–348.15 K, pressures of 0–200 kPa, and r of 0.8 and 1.0 mol·mol −1 . The total solubility of H 2 S increases with decreasing temperature, increasing pressure, and decreasing r . The measured solubility data were fitted by the reaction equilibrium thermodynamic model. Chemical reaction equilibrium constant and the Henry's constant at different temperatures and different r were obtained. The average relative error of model fitting is less than 3 %. The results show that the chemical reaction equilibrium constant and the Henry’s constant both decrease with the increase of r , and decrease of temperature. Effect of molecular structure on reaction equilibrium constants was explained by quantum chemistry calculation. The absorption of H 2 S in r FeCl 3 / [Nbmm]Br at low pressure is dominated by chemical absorption. With the increase of pressure, the proportion of physical absorption continues to increase, and gradually occupies the main part.