Carbon dioxide solubility in Deep Eutectic Solvents: Modelling using Cubic Plus Association and Peng-Robinson equations of state

Abstract

Carbon Dioxide (CO2) is the greenhouse gas that most contributes to global warming and climate change due to fossil fuels combustion, transportation, and other industrial process. Carbon capture, storage, and utilization (CCSU) is an effective method to reduce CO2 emission. Chemical absorption is the most straightforward technology for post-combustion CO2, and monoethanolamine (MEA) has been proved to be the most efficient chemical solvent. However, MEA is not environment friend, thus indicating the need for developing eco-friendly absorbers for CO2 capture, such as Deep Eutectic Solvents (DESs). Despite recent experimental studies investigating CO2 solubility in DESs, thermodynamic modelling is important to understand the system behavior. Thus, this study modelled CO2 solubility in thirteen DESs found in a large range of temperature (from 303.15 to 343.15 K) and pressure range (from 0.06 to 12 MPa). Cubic-Plus Association (CPA) and Peng-Robinson 78 equations of state were used to compare efficiency. The results indicate that fitting the binary interaction parameter (kij) promotes a better reproduction result than considering kij equals zero. Despite all association schemes of CO2 providing accurate results, the 4 C association scheme (two electron acceptors and two electron donors) resulted in better equilibrium description. Both models describe experimental data very well, yet the individual component approach presents better results than pseudo-component approach, corroborating with DESs definition.