SO _{Research 2} Capture The Behavior Of Ionic Liquids Regulation

Sulfur dioxide (SO2) is an air pollutant, which will threaten human health and natural environment, where the capture of SO2has attracted extensive attention. As a kind of new solvent, ionic liquids (ILs) are seen as a promising alternative for SO2capture owing to their unique properties such as negligible vapor pressures, wide liquid temperature ranges, high thermal stability and tunable properties. Many kinds of functionalized ILs were developed for SO2capture, although the results are inspiring, there are some shortages, such as poor reversibility and high cost. Furthermore, these functionalized ILs are usually expensive and their synthesis requires several synthetic steps, which limits their commercial application. Thus, we need to develop some novel, good absorption performance and economically viable ILs for SO2capture.Firstly, a new method on improving the capture of SO2through tuning the structure of the IL was proposed. The essence of our strategy is to decrease the electronegativity of the interaction site of the IL. Thus, ILs containing less electronegative sulfur or carbon-centered site were used for SO2absorption. These ILs showed excellent reversibility (30cycles) and extremely high available SO2absorption capacity (up to1.13g per g IL). Through quantum chemical calculation and spectroscopic investigation, we find that the absorption enthalpy of these ILs is lower than that of ILs containing electronegative oxygen or nitrogen-centered site, thus the reversibility of these ILs becomes better. Furthermore, these ILs exhibited chemisorption of SO2and their molecular weight is very low, leading to their high SO2absorption capacity.Secondly, a series of dual functionalized ILs with metal chelate cations were developed, which could be easily prepared from cheap materials, eliminating intensive synthesis of traditional functionalized ILs and lowering the cost. Through a combined interaction of acidic SO2with basic anions and ether-containing cations, these ILs showed high absorption capacity. Besides, their physical properties and absorption performance could be easily tuned, such as changing metal ions, coordination number and functionalized anions. It was emphasized that the absorption and desorption of SO2by these ILs was significantly affected by the metal ions, which opens a door to tune the capture of acidic gas.In summary, two kinds of new functionalized ILs were designed and used for SO2capture, where the SO2absorption capacity and reversibility of ILs were improved. The SO2absorption mechanism was also investigated through spectroscopic investigation and quantum mechanical calculation. These works open a door to achieve high capacity, low cost as well as excellent reversibility for acidic gas capture such as SO2by ILs.