Synthesis Of Novel Organic Amines And Research On CO₂ Absorption Properties

Industrial production is the main source of CO₂ in the air,therefore,capturing CO₂from the emission source is the most effective way to reduce emissions.Among them,chemical absorption is the main method for capturing CO₂ in industrial flue gas,and organic amines are commonly used CO₂ absorbent.However,the problems of strong alkalinity,strong corrosiveness,high regeneration energy consumption and low absorption capacity of common organic amine absorbents have always existed.In order to make up for these deficiencies,researchers at home and abroad usually use the method of compounding different organic amines,and there are few studies on adjusting the basicity of organic amines by introducing electron-withdrawing groups.Aiming at the problems of common organic amine absorbents,this paper designs an experimental process by introducing electron withdrawing groups,and explores the pH,viscosity,thermogravimetric,desorption and thermal stability properties.The experiment used acrylonitrile to react with three CO₂ absorbents,ethylenediamine,ethanolamine and ammonia.By controlling the feeding ratio,synthesizing secondary amines,designing orthogonal experiments to explore the optimal synthesis conditions and investigate the influence of time,temperature and material ratio on the synthesis results,through the non-aqueous titration method of perchloric acid-glacial acetic acid and 2,4-pentanedione method to titrate the product for purity.After that,the three synthesized substances were characterized by infrared,nuclear magnetic and mass spectrometry,and the characterization results were consistent with the product structure.In order to explore whether the three substances are suitable for CO₂ capture,their physical properties were analyzed,and it was concluded from the physical property analysis experiment that after the introduction of the cyanoethyl electron-withdrawing group,the pH values of the three substances were significantly higher than before.The viscosity of the three substances is relatively large,and in practical applications,they need to be prepared as aqueous solutions;the boiling points of the three substances all exceed300℃;the three substances are relatively stable,and at 120℃ and below 120℃,none of the three substances Thermal cracking will occur.From the physical property data of N,N’-bis（2-cyanoethyl）ethylenediamine,3-[（2-hydroxyethyl）amino]propionitrile and 3,3’-iminodipropionitrile Aqueous solutions of the three substances are suitable for CO₂ capture.Therefore,1 mol/L aqueous solution was prepared respectively,and the flue gas absorption environment was simulated and the critical desorption temperature was set,absorption at 40℃,regeneration at 100℃,and finally obtained:N,N’-bis（2-cyanoethyl）ethyl The CO₂ absorption effect of the diamine aqueous solution is better,the absorption effect of the 3-[（2-hydroxyethyl）amino]propionitrile aqueous solution is second,and the CO₂ absorption effect of the 3,3’-iminodipropionitrile aqueous solution is poor.During multiple absorption and desorption,it was found that the pH value of the solution could not be completely recovered and the absorption capacity gradually decreased,so the thermal stability experiment of the aqueous solution was carried out.Through the thermal stability experiment,it was concluded that the hydrolysis of the cyano group occurred in the three organic amine absorbents in the presence of water and a constant temperature of 100℃,resulting in a decrease in the pH value of the solution.