Capturing CO2 from industrial gases is one of the important ways to mitigate the globe warming effective, and it is well known the technological obstacles do not exist since several technologies, such as absorption, adsorption, membrane separation, have been used commercially for many years. However, a big challenge we are meeting now is we need treat gigantic amount of the gases if we take the reduction of CO2 emission as the final objective, thus the huge energy consumption for CO2 capture has been regarded as the real obstacle to realize the CO2 capture with large scale.
In recent years, ionic liquid solvent has being regarded as a prospective solvent for CO2 capture, especially its potential advantage to reduce the energy consumption greatly. However, commercial running such new technologies requires us to consider: absorption with high efficiency, desorption with low energy consumption, low cost of the IL solvents, high stability of the solvents and excellent environmental performance after long term utilization.
In this work, a new alkanolamines-based ionic liquid, 2-[2-hydroxyethyl (methyl) amino] ethanol tetrafluoroborate (MDEABF4), were synthesized, which partly possesses the above required performance for capture CO2. The basic physico-chemical properties and the absorption performance of the new ILs solvent have been studied and a series absorption curves have been obtained. A new mechanism of CO2 capture was proposed through the in situ IR analysis. Furthermore, the ionic liquid-based composite solution consisting of 2-[2-hydroxyethyl (methyl) amino] ethanol (MDEA), MDEABF4, piperazine (PZ), and H2O, was investigated for CO2 capture. Moreover, we found that the new solvent has lower causticity than the amine solvent. A multi-scale simulation method was applied to simulate the CO2 capture process. Firstly, a priori prediction is employed to obtain thermodynamic data of the IL-containing system including activity coefficients, equilibrium vapor pressures and Henry constants with a QC continuum salvation model (CSM) COSMO-RS. Then, the interaction parameters in Electrolyte NRTL model are fitted to data from COSMO-RS to predict the physical properties and phase equilibrium data of the novel system over a wider range of concentration and temperature. Based on these parameters, process simulation was carried out with ASPEN plus. The simulation results show that the new process could save the regeneration energy consumption more than 30% compared with the amine method. Due to the above excellent properties of the new solvent and the new process, it would be an new generation solvent for CO2 capture.