Synthesis And Characterization Of A Hydroxypridine Ionic Liquid And Its Complex Solution For Capturing CO₂

With the development of human civilization,the rapid progress of industrialization,a large number of carbon dioxide（CO₂）was discharged into the air,which caused serious harm to human health and ecological environment.Therefore,CO₂ energy-saving emission reduction work without delay.The ionic liquid has a series of excellent characteristics such as nonvolatile,nonflammable,strong conductivity,low vapor pressure,stable physical and chemical properties,and has become an excellent CO₂ capture reagent.At present,domestic and foreign scholars have studied different kinds of ionic liquids（such as conventional ionic liquids,functionalized ionic liquids,etc.）.However,the ionic liquid still has the problems of complicated preparation process,low absorption capacity and large viscosity.At present,the widely used organic amine CO₂ capture reagent is highly corrosive and easy to decompose at high temperature.It is necessary to carry out the work of studying the new CO₂ capture solvent.In this paper,a series of functionalized ionic liquids for the absorption of CO₂ were designed and synthesized,which provided the idea for the development of efficient ion-trapping CO₂ technology.At present,functionalized ionic liquids mainly absorb CO₂ in the presence of anions or cationic electrons with strong anodic acid（such as N or O）in ionic liquids.Since each ionic liquid has only one site of action,this results in an ionic liquid with a maximum absorption capacity of only 1mol CO₂/ mol IL.In order to improve the absorption capacity of CO₂ by ionic liquids,we designed and synthesized the use of two CO₂ absorption sites of hydroxypyridine type ionic liquids for CO₂ capture.Among them,the absorption capacity of [P4444][2-Op] to CO₂ can reach to 1.2mol CO₂/ mol IL.By studying the CO₂ absorption of the hydroxypyridine ionic liquid and the physical characterization of the ionic liquid,it is known that the anions and cations of the cationic quaternary phosphonium hydroxypyridine ionic liquid have a role in the CO₂,and the two action points have some synergies.Because of this double-site absorption and cationic synergistic effect,this type of ionic liquid has a higher absorption capacity for CO₂.In addition,through the ionic liquid absorption of CO₂ cycle experiments we can find that such ionic liquid has a good cycle performance.Hydroxypyridine ionic liquid is a potential candidate for CO₂ capture,which provides a new direction for the development of new CO₂ capture reagents for capture and industrial applications.In order to facilitate industrial applications and solve the problem of high viscosity of hydroxypyridine ionic liquids,we mixed1,8-diazabicycloundeca-7-ene（DBU）with hydroxypyridine ionic liquids.The synergistic effect between DBU and ionic liquids is reduced while reducing the viscosity of the complex system,which increases the absorption capacity of CO₂ by ionic liquids.The absorption capacity of the mixed absorption solvent DBU-[P4444][2-Op] is up to 1.41 mol CO₂ /mol IL.In addition,the CO₂ absorption behavior of complex system formed by N-methyl diethanolamine（MDEA）-hydroxypyridine ionic liquid was also investigated.The absorption capacity of CO₂ in this complex system（MDEA-[P4444][2-Op]）reached to 1.37 mol CO₂ / mol IL.It can be seen that the organic solvent and the hydroxypyridine type ionic liquid are mixed to form a mixed system.This mixture can not only increase the absorption capacity of CO₂,but also can effectively reduce the viscosity.The combination of ionic liquids provides a feasible way for the practical application of hydroxypyridine ionic liquids.