Design And Preparation Of Novel Anion-functionalized Ionic Liquids And Their Absorption Peformance For Sulfur Dioxide

Air pollution is still a serious problem in our country,espically sulfur dioxide?SO₂?which comes from the burning of fossil fuels,has harmed the health of mankind severly.Nowdays,the conventional removal processes for flue gas desulfurization?FGD?applied in industry still have some inherent disadvantages,including the production of large quantities of wastewater and useless byproducts.Ionic liquids?ILs?have provided an alternative choice for FGD due to their unique properties,such as ultra-low vapor pressure,high thermal stability,wide liquid temperature range,and tunable structure and properties.However,there are several problems that hindered the application of ILs,such as low absorption capacity and difficulty in desorption.As a part of the researches of the project supported by the National Natural Science Foundation of China?No.21403059?,several kinds of novel functionalized ILs have been developed in this work to solve these problems.Furthermore,the absorption mechanism has been investigated through spectroscopic analysis and quantum calculations.The main content of this thesis are as follows:?1?A new strategy based on cyano-containing anion-functionalized ILs for improved SO₂ capture by tuning the basicity of the anion has been proposed.A class of cyano-containing anion-functionalized ionic liquids with different basicity were designed,and prepared.The interaction mechanism between these cyano-containing ILs and SO₂ was investigated by FTIR,NMR and quantum chemical calculations method.The results showed that dramatic effects on SO₂ capacity originate from the basicity of the ILs and enhanced cyano-sulfur interaction.?2?A class of acylamido-based anion-functionalized ionic liquids with multiple reaction sites has been prepared.The investigation suggests that the introducing of acylamino group not only increased the absorption capacity but also dramatically decreased the absorption enthalpy.The mechanism study revealed that the strong C=O···S interaction and C-H···O hydrogen bonding between SO₂ and N and dual C=O reaction site are the main reason why these anion-functionalized ILs have such highly efficient absorption for SO₂.?3?To solve the problem of low capacity of SO₂ under low partial pressure,a class of formyl-containing anion-functionalized ILs have been designed and prepared.And we proposed a new strategy for highly efficient SO₂ capture under low partial pressure through dual-site absorption mechanism.The SO₂ absorption mechanism under low partial pressure of these anion-functionalized ILs was investigated by FTIR,NMR and quantum chemical calculations.It was found that the remarkable enhancement of SO₂ absorption capacity was due to the strong C=O···S interaction and C-H···O hydrogen bonding of SO₂ and N with formyl reaction site when the partial pressure of SO₂ was 0.01 MPa.Besides,it becomes much easy for SO₂ desorbed from ILs after introducing the formyl group on the anion.