Synthesis And Application Of Ether Bis-imidazole Ionic Liquid For Sulfur Dioxide Absorption

The combustion of coal has resulted in the emission of SO₂,which caused environmental pollution and is harmful to the individuals.Flue gas desulfurization?FGD?is in urgently needed.But the traditional desulfurization technology has some promblems such as high energy consumption,secondary pollution and so on,thus failing to meet the requirements of friendly environment.Finding an environmental friendly and high effective desulfurizing agent has become an urgent task.Ionic liquid has some advantages on absorbing SO₂ and the related work has been published.While the SO₂ removal of double-nuclear ionic liquid in this field has less report.In this work,ether-based bis-imidazole ionic liquid-?3-ethylene glycol methyl ether-1-imidazole?butyl dimethyl sulfonate was synthesized by using imidazole,1,4-dibromobutane,ethylene glycol monomethyl ether and methylsufonyl chloride as raw material.The produced bis-imidazole ionic liquid was characterized by FTIR,MS and¹HNMR.The density,viscosity and surface tension were measured at the temperature range of 293.15 to 348.15 K.Besides the thermal stability was measured too.Then,desulfurization,selection and regeneration properties of the ionic liquid synthesized were carried out.The absorption mechanism was also investigated.Immobilized ether based bis-imidazole ionic liquid was produced by loading ionic liquid on silica gel.The effects of loading amount on the desulfurization performance of the ionic liquid was studied.A series of experiments showed that:?1?The density,viscosity and surface tension of ether bis-imidazole ionic liquid decrease with the increase of temperature;while below 400?,the structure of the ionic liquid is stable.?2?The desulfurization properties of ether bis-imidazole ionic liquid decreases with the increase of temperature.At 25?,the saturated molar absorption amount reaches up to4.05mol SO₂/molIL,with a higher absorption rate;it can be completely desorbed at 100?.The desulfurization properties increases when the partial pressure of SO₂ in the gas mixture increases.In the same absorption conditions,the absorption quantity of ether bis-imidazole ionic liquid was much higher than that of CO₂,which means that the ionic liquid has a higher selectivity to SO₂.The ionic liquid can be recycled at least five times with loss of its initial performance and no loss in quality.Under the experimental conditions,the absorption of ether bis-imidazole ionic liquid on SO₂ belongs to physical absorption.?3?The desulfurization performance of immobilized ether bis-imidazole ionic liquid on silica gel will firstly increase and then decrease,when the loading amount increased.