Research On The Synthesis And Desulphurization Performance Of Amine Ionic Liquids

With the rapid development of heavy industry which consumpts large amounts of energy,in our country the emissions of SO₂ have ranked first for many years.SO₂ is a main kind of pollutant and at the same time a major sulfur resource.However,traditional absorbents not only cause secondary pollution,but bring about heavy losses of sulfur resource.In recent years,ionic liquids have drawn great attention in flue gas desulfurization,with excellent features of little vapor pressure,high thermostability,recyclability,designability and ability for sulfur resource collection.According to the two ways of sulfur resource collection---SO₂ gathering and collection as well as ammonia desulphurization,low-cost and low-viscosity amine and sulfoxides ionic liquids were designed respectively and their desulphurization performances were discussed in this research.Based on this,pilot tests were conducted and the results were as follows.1)With n-propylamine,ethylenediamine and ethanolamine as cationic material and lactic acid,phenol,imidazole,triazole,tetrazole and 1H-Tetrazole-1-acetic acid?TAA?as anionic material,amine ionic liquids are synthetised with one-step method,¹H-NMRand IR are characterized to test their density,viscosity,surface tension and other physical properties under normal temperature,the absorbability of ionic liquids for SO₂ is discussed,and ionic liquids are studied in their mechanism of desulfurization,selectivity,stability and recyclability.The results show that under the temperature of 25?,the viscosities of propylamine phenoxide,propylamine lactate,propylamine tetrazole acetate and ethanolamine lactate are 66.2cp?2477cp?6964cp?3250cp;the viscosity of propylamine phenoxide is far lower than those of other liquids.Their absorbabilities for SO₂ are as follows:ethanolamine lactate>propylamine tetrazole acetate>propylamine lactate>propylamine phenoxide.The n_e?SO₂?:n_e?IL?of ethanolamine lactate under the temperature of 40?is 0.92;The n_e?SO₂?:n_e?IL?of propylamine phenoxide under the temperature of 30?is 0.57.Through the comparison of ¹H-NMR and IR atlas before and after desulfurization,it is proved that amines ionic liquids can be used for both chemical and physical absorption.2)Pilot test devices of packing absorbing column are designed and set up.Ethanolamine lactate is synthesised with 50L high pressure reactor and it is mixed with water as desulfurizer whose water content is 15%.The recyclability of desulfurizer used in experiments and the accumulation of acid in desulfurizer are discussed.The results show that after 5 cycle experiments,the amount of saturated absorption of desulfurizer keeps unchanged in the latter 4 times,its recyclability is better and the exhaust gas can reach the standard.With the increase of cycle-index,the cumulants of SO₄^2-will increase successively,while the amount of SO₃^2-and pH will decrease gradually.3)Three kinds of unctuous sulfoxides ionic liquids are designed and synthesised,which can be used for absorption and catalysis.A pilot unit of four parallel bubbling gas absorbing towers for ammonia desulfuration is set up.pilot tests were conducted with ionic liquid as catalyst and mixed liquid of water-ammonia water as desulfurizer.The results show that the synthesised sulfoxides ionic liquid can oxidize the absorbed SO₂ into SO₄^2-in situ,which enhances desulfurization effect.And ionic liquid can be separated from desulfurizer through stratification and its recyclability is better.After comparison of the oxidation rate and physical properties of ionic liquids,number 5 and 7 ionic liquids are selected by reason of their good thermostability,high oxidation rate and good desulfurization effect.What's more,compared with the desulfurzer used in the factory,number 5 and 7 ionic liquids are better.In this research,the problem of blue smoke of ammonia desulphurization is solved,its desulfurization effect is greatly improved,and the implication of ammonia desulphurization is promoted.