Synthesis Of Functionalized Ionic Liquids For The Absorption Of Sulfer Dioxide

From the burning of fossil fuels,a large amount of acid gases such as sulfer dioxide?SO₂?and carbon dioxide will result in series problems including acid rain,greenhouse effect and other hamful to environment and human health.Therefore,the dramatical development of new technologies,environmentally friendlly and energy saving for the decreasing of SO₂ emission is highly desired.In recent years,ionic liquids?ILs?with unique traits,for instance,the wide liquid temperature range,high thermal stability,negligible vapor pressure,and virtually limitless chemical tenability,provide a new method for acid gas capture.Fucntionalized ILs have an excellently effect of absorbing acid gases,and it is an important challenge to design novel functionalized ILs to achieve high efficiency,high reversible and energy saving goals in acid gases capture.As a part of the research work supported by the National Natural Science Foundation of China?No.21403059?,we designed,synthesized,and characterized several novle kinds of functionalized ILs through“limited number of active sites”and“computer-assisted design”stratiges to improve SO₂ catprue and separation.The main research parts are as fellows:?1?Through“limited number of active sites”strategy,we designed and synthesized a kind of anion-functionalized ILs with fluorinated acetylacetonate anions.The physical properties of these fluorinated acetylacetonate ILs,such as density,viscosity,were studied.It was found that this kind of IL had high thermal stabilities,and the densities decreased with the increase of temperature,what's more,the density and temperature has a linear connection.In addition,the relationship between viscosity and temperature was consistent with the Arrhenius formula.?2?These fluorinated acetylacetonate ILs?FILs?on the performances of SO₂ absorption were investigated.In addition,SO₂ capture under low partial pressures and different temperatures by these FILs has also been investigated.Due to the multiple-site interactions between SO₂ and the limited number of active sites on the anion,the higher SO₂ capacitites by theses FILs than conventional[TFSI]-based IL could be achieved.In addition,the rapid absorption/desorption rate and excellent reusability of these FILs are very attractive for practical applications in acidic gas absorption.?3?Several kinds of substituted imidazolate-based ILs were designed and synthesized for SO₂ capture.The absorption enthalpy,basicity of ILs,absorption capacity could be easily tuned.What's more,the substituted imidazolate-based ILs could also reversibly capture of SO₂.The relationship between the pK_a and the absorption capacities of substituted imidazolate-based ILs is consistent with the relationship between the pK_a and absorption enthalpies calculated by DFT.?4?Using computer-assisted design method,we first calculated the absorption enthalpies of two SO₂or one CO₂,and the predicted selectivity S_p defined as?H_anion-2SO2/?_Hanion-CO2.Then we discovered that S_P was enhanced when the basicity of ILs was reduced.We also measured the absorption capacities of 10vol%SO₂ or 100 vol%CO₂ by these ILs,and the selectivity S_0.1/1 defined as C_SO2,0.1/C_CO2,1.It is found that the relationship between p K_a and S_0.1/1 from experimental data consistent with the relationship between pK_a and S_p.