High pressure measurement and CPA equation of state for solubility of carbon dioxide and hydrogen sulfide in 1-butyl-3-methylimidazolium acetate. (October 2015)

• Record Type: Journal Article
• Authors: Haghtalab, Ali; Kheiri, Alireza
• Is Part Of: Journal of chemical thermodynamics. Volume 89(2015:Oct.)
• Page Start: 41
• Page End: 50
• Publication Date: 2015-10
• Subjects: Acid gas solubility -- [bmim][Acetate] -- H2S -- CO2 -- CPA EOS; Thermodynamics -- Periodicals; Thermochemistry -- Periodicals; Thermodynamique -- Périodiques; Thermochimie -- Périodiques; Thermochemistry; Thermodynamics; Periodicals; 541.369
• DOI: 10.1016/j.jct.2015.04.032
• Languages: English
• ISSNs: 0021-9614

Abstract

Highlights: Solubility of carbon dioxide in pure [bmim][acetate] is measured. Simultaneous solubility of CO2 + H2 S in [bmim][acetate] is measured. Both physical and chemical models are applied to modelling the (acid gas + IL) systems. The CPA EoS is used for phase equilibrium calculation. A reaction thermodynamic equilibrium model is used in liquid phase. Abstract: Removal of acid gases such as CO2 and H2 S from natural gas is essential for commercial, safety and environmental protection that demonstrate the importance of gas sweetening process. Ionic liquids (IL) have been highly demanded as a green solvent to remove acid gases from sour natural gas and capturing of CO2 from flue gases. In this work, the solubility of CO2 in 1-butyl-3-methylimidazolium acetate ([bmim][Ac]) is measured at temperatures (303.15, 328.15, 343.15) K and pressure range of (0.1 to 3.9) MPa. Moreover, the experiments are carried out for simultaneous measurements of (CO2 + H2 S) (70% + 30% on a mole basis) solubility in the same ionic liquid at T = (303.15, 323.15, 343.15) K and a pressure range of (0.1 to 2.2) MPa. To model the solubility of acid gases in IL, both physical and chemical equilibria are applied so that the (vapour + liquid) equilibrium calculation is carried out through Cubic-Plus-Association (CPA) EoS. The reaction equilibrium thermodynamic model is used in liquid phase so that the chemical reaction is taking place between IL and acid gasses. The Henry's and reaction equilibrium constants are obtained though optimization of the solubility data. Using CPA EOS, the pure parameters of [bmim][acetate] are optimised and consequently using these parameters, gas partial pressure calculation is performed for the (CO2 + IL) and (CO2 + H2 S + IL) systems. For the (CO2 + IL) system, the percent average absolute deviation (AAD%) of 4.83 is resulted and for the (H2 S + CO2 + IL) system the values of 18.8 and 13.7 are obtained for H2 S and CO2, respectively.