| "Greenhouse effect" is one of the major environmental problems in the 21st century.CO2 is the main greenhouse gas,accounting for 2/3 of the greenhouse gas.Ionic liquids are organic salts that refer to liquids consisting only anions and cations,having a very wide range of applications with excellent thermal stability,good solubility,eximious conductivity and splendid structural designability.The method that capture CO2 by traditional ionic liquid solves many industrial problems,such as the great loss,strong corrosion and high regeneration energy of organic amine solution in industry.But,the trapping process is very slow because of the formation of solid or high viscous gel products.It is an urgent problem to improve the capacity of capturing CO2 under the condition of decreasing the effect of corrosion and high regeneration energy.Under the background.We have designed and synthesized six kinds of functional ionic liquids,and prepared ionic liquid compound solution to absorpt simulated flue gas.Not only rapid capture of C02 but also ease of separation and reusability are achieved.(1)1-aminopropyl-3-methylimidazolium tetrafluoroborate,1,3-dipr-opylaminoimidazolium tetrafluoroborate were synthesized.At the same time,a series of characterations were made,such as FT-IR,1HNMR,viscosity and density etc.Test results showed that low temperature conducive to absorption.When the absorption temperature is in range of 283-293K,the best CO2 absorption capacity of 1-aminopropyl-3-methyl-imidazolium tetrafluoroborate and 1,3-dipropylaminoimidazolium tetra-fluoroborate are 0.424mol CO2/mol IL and 0.894mol CO2/mol IL.Reusing test showed that there is no significant decrease in C02 absorption capacity of ionic liquids after being reused more than 10 times.(2)Four amino acid ionic liquids were synthesized to with greater density of basic groups for which is benefit to capturing more CO2 and is biodegradable easily.At the same time,a series of characterations were made,such as FT-IR,1HNMR,viscosity and density etc.Test results showed that saturated CO2 absorption capacity from high to low are bis-(3-methyl-1-imidazole)butyldiproline,bis-(3-methyl-1-imidazole)-butyl diglycine,bis-(3-methyl-l-imidazole)butyl dialanine,bis-(3-methyl-1-imidazole)butyl dilysine at the best absorption temperature(283K).We can see that,the anion structure has a significant impact on the CO2 capture.The amino group of proline anions is secondary amine.Its conjugated acid pKa is 10.6 with relatively strong alkalinity.The best C02 absorption capacity of bis-(3-methyl-l-imidazole)butyl diproline is 0.971 mol CO2/mol IL.Although there are two amino groups on bis-(3-methyl-1 imidazole)butyl dilysine,its CO2 absorption capacity is only 0.592 mol CO2/mol IL because of its larger viscosity.In addition reusing test showed that there is no significant decrease in CO2 absorption capacity of ionic liquids after reused 10 times.(3)In order to investigate industrial application of the synthesized ionic liquids,we examined CO2 the absorption effect of ionic liquid complex solutions in consideration of the problem of large viscosity of amino functionalized ionic liquids,N2 and CO2 mixtures were used as simulated flue gas,and we examined the effect of the proportion of ionic liquids,the type of compounding solvent,and the ratio of simulated flue gas on the CO2 absorption capacity.The test results showed that when 5%ionic liquid + 95%ethylene glycol was used as absorbent,the maximum absorption capacity of bis-(3-methyl-1-imidazole)butyl dilysine is 2.143 mol CO2/mol IL.The simulated flue gas results showed that when the C02 content was 10-100%,the absorption capacity of the ionic liquids compound solution is 1.562-2.143mol CO2/mol IL,which is much higher than the value of 0.547 mol CO2/mol IL in the literature.It is expected to realize its application in industrial CO2 capture. |
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