Abstract
As part of CO(2) capture strategies, ionic liquid-based CO(2) absorbents have gained attention for their tunable properties to lower the energy costs for CO(2) capture. In this study, a series of borate-based nonamine functionalized ionic liquids (ILs), incorporated with magnesium acetylacetonate, were developed and investigated for its CO(2) capture capability at moderate temperature under ambient pressure. Nuclear magnetic resonance and Fourier transform infrared spectroscopy confirmed the successful incorporation of acetylacetonate ligands into the fluorinated-lithium borate ionic liquids. Comprehensive analyses of the physical and thermochemical properties revealed that the synthesized ILs remain stable below 200 °C, with the borate structure and acetylacetonate ligands intact. The ILs functionalized with fluorinated alcohol and magnesium acetylacetonate enhance the CO(2) uptake capacity by 55% in comparison with the original lithium borate ILs, suggesting the enhanced cooperative interactions responsible for improved CO(2) capture performance. The carbon capture mechanism was identified to proceed via physical absorption, as evidenced by minimal changes in the characterization results and viscosity after CO(2) absorption. The enthalpy of CO(2) absorption (ΔH (a)) for the synthesized ILs were determined experimentally by using differential scanning calorimetry to be in the range from -12.4 kJ mol(-1) to -18.9 kJ mol(-1), which are much lower than that of conventional amine solutions (e.g., MEA: -82 kJ mol(-1)) and amine-based ILs ((e.g., [Bmim]-[Ac]: -45.8 kJ mol(-1)). These findings suggest that lithium borate-acetylacetonate ILs offer a promising approach for a CO(2) capture system under ambient conditions.