A Study On Degradation And Reclamation Of Aqueous 2-(2-Aminoethylamine-Ethanol Solution For CO₂ Capture

CO2 emission,capture and utilization have attracted great attention,as the problems caused by global warming become more and more serious.The main resource of CO2 is the usage of fossil fuels such as coal and petroleum.It will significantly benefit society and economics to recover CO2 from flue gas emission.Among numbers of different CO2 capture technologies,chemical absorption method using alkanolamine as solvents is the most mature technique.2-(2-aminoethylamine-ethanol(AEEA)has proved to be a promising solvent on CO2 capture,as a result of solvent selection.In this study,we have investigated the degradation and reclaimation of AEEA in order to improve the CO2 capture efficiency and reduce the energy consumption.This study mainly took three degradation ways into account: the degradation caused by acid gas SO2,the oxidative degradation and thermal degradation.The influence of gas concentration,CO2 loading,temperature and reaction time on the capture capacity and desorption efficiency of AEEA were studied.Physical property and total alkalinity of the AEEA aqueous solution were determined before and after experiments.Degradedsamples were analyzed by using gas chromatography-mass spectrum analysis(GC-MS)and ion chromatography(IC)for final concentration and identification of the degradation products.Results from the degradation caused by SO2 revealed that the CO2 absorption ability and total alkalinity would decrease with the increase of SO2 concentration in flue gas,so as the increase of temperature in oxidative degradation and CO2 loading in thermal degradation.Meanwhile,in SO2 degradation,a higher gas concentration would reduce the desorption efficiency,in contrast to the desorption tendency in thermal degradation.The IC analysis proved that SO2 absorbed into AEEA aqueous solution mainly transformed into anion SO32-/SO42-,which could not exist stably when heated in 423.15 K for 16 days at most.Six oxidative degradation products were identified.The three primary products include carbamate,ethanediamine and monoethanolamine.Three secondary products include 1-(2-hydroxyethyl)piperazine,1-(2-hydroxyethyl)-2-imidazolidinon.Two similar products were identified in thermal degradation.The influence of oxidative degradations was higher than thermal degradation,which was negligent when the solvent was free from CO2.In addition,the reclaim experiments were approached when degradation occurred by SO2.We have tried to reclaim AEEA by ion exchange resin.After a series screening tests,we found the high efficiency resin D201 which have a theoretical ion loading capacity of 3.7mmol/g.The ion exchange process should be arranged behind the stripper unit,and the stripper temperature was not lower than 373.15 K.The resin could also adsorb AEEA,so we need to wash the resin with deionized water at last.The determination of physical property and total alkalinity revealed the high recla im efficiency of ion exchange method,which could be potentially used in industry.