As concern continues to climb about the effects of anthropogenic global warming, research interest in carbon capture technologies is rising. Currently, the common methods of CO2 capture involve the use of volatile, corrosive solvents and require substantial energy to be diverted for the process. One class of solvents that can potentially solve these problems is ionic liquids.
Ionic liquids (ILs) are organic salts with melting temperatures below 100°C. ILs have many properties that make them attractive as potential solvents in many different types of processes, properties such as high thermal stability, almost negligible volatility at ambient temperatures, good solvation properties and being non-corrosive. Research has also shown ILs to have a strong affinity for CO2 and, because of the wide range of cation and anion combinations, ILs can be tuned to provide even higher uptake capacities, especially by attaching functional groups that can bind with CO2. In order to successfully implement ILs in carbon capture processes, thermodynamic data is required for IL-CO2 systems, particularly the enthalpy of physical and chemical absorption.
This work is concerned with the measurement of gas solubilities of interest to carbon capture technologies, CO2, N2 and H2S. CO2 solubilities were measured to determine thermodynamic properties necessary to process design. Knowledge of N2 solubility is lacking in literature, particularly the effects of CO2-IL complexes on solubility and results were determined to understand how to predict the likely behavior of CO2 and N2 in flue gas with ILs. Finally, H2S was measured to determine how IL structure effects the solubility of this hazardous pollutant often found in chemical processes.
Gas solubilities measurements are used to determine the equilibrium constants of chemical absorption and the Henry’s law constants of physical absorption which are utilized to obtain the enthalpy and entropy of absorption for process conditions.