The Applications Of Aza-based Ionic Liquids And Pseudo Ionic Liquids In The Capture Of Carbon Dioxide

With the increase of CO₂ concentration in the atmosphere,the greenhouse effect is intensified,and how to effectively reduce CO₂ emissions has become the key of people’s research.Traditional CO₂ capture methods have some problems of volatile absorption medium and low decarbonization efficiency,which can’t meet the requirements of green and sustainable development.In recent years,ionic liquids and pseudo ionic liquids（deep eutectic solvents）have attracted wide attention in the field of CO₂ capture due to their low saturated vapor pressure,strong thermal stability,and adjustable structure.They are regarded as promising CO₂ absorbents.Among them,functionalized ionic liquids and deep eutectic solvents based on aza-based have been proven to have good CO₂ capture performance.Inspired by this,in this paper,we adjusted the structures of ionic liquids and deep eutectic solvents,synthesized two types of aza-based ionic liquids and pseudo ionic liquids for CO₂ absorption and studied the absorption process and mechanism.The main contents are as follows:In this project,a one-step method was used to synthesize a diamine-azole protonic ionic liquid 3-dimethylaminopropylamine tetrazole[DMAPA][Tetz]and the effect of temperature on the absorption performance was investigated.It was found that the CO₂uptake of the absorbents decreased with the temperature increasing under normal pressure and it exhibited the best CO₂ absorption performance at 25°C（16.73 wt%）.The test showed that the absorbent has good thermal stability and recycling performance,and the CO₂ absorption enthalpy of the absorbent is low（-31.2 k J/mol）,which is beneficial for CO₂ desorption.Combining the experimental results,FT-IR and NMR analyses and quantum chemical calculations,revealing that the efficient CO₂absorption of[DMAPA][Tetz]can be attributed to the chemical interaction between the N atom basic site on the azole-based anion in[DMAPA][Tetz]and CO₂.In addition,we also studied the effect of solvents on the physical properties and absorption performance of ionic liquids by adding ethylene glycol into ionic liquids,which provided ideas for the subsequent development of ionic liquid absorbents with applicability.Subsequently,a series of superbase/acylamido-based deep eutectic solvents were synthesized based on the multiple-site strategy and their physical properties and absorption-desorption performance were studied.The results showed that when the molar ratio of 1,5-diazabicyclo[4.3.0]non-5-ene（DBN）and 2-imidazolidone（EU）is2:1 at normal pressure,the CO₂ absorption capacity of the corresponding deep eutectic solvent could reach 23.02 wt%at 25°C and it can keep stable during 5 consecutive absorption/desorption cycles,the absorption performance did not have significant changes.In addition,DBN-EU（2:1）can not only desorb CO₂ faster at 80°C,but also has a higher CO₂ desorption ratio（about 86%～87%）,and the absorption enthalpy of DBN-EU（2:1）is-83.4 k J/mol,which indicated that the absorbent has great potential to be used as a medium in CO₂ efficient capture.FT-IR,NMR analyses and quantum chemical calculations were used to clarify the absorption mechanism of CO₂ by DBN-EU（2:1）,and it was found that the efficient absorption performance of the absorbent is due to the multiple-site interaction between the acylamido anion and CO₂.