Research On Desorption Of CO₂ And Corrosion In Ionic Liquid-Alkanolamine Aqueous Solution

Monoethanolamine（MEA）,diethanolamine（DEA）,N-methyldiethanolamine（MDEA）and their mixed amine solutions are usually used as adsorbents to capture CO₂.These absorbents have the advantages of large absorption capacity and high reaction rate.However,the regeneration temperature and the energy consumption are high,and the corrosion of equipment is serious.The amino acid ionic liquid（AAIL）has advantages in CO₂ capture because of its good thermal stability,small vapor pressure,high CO₂ solubility and low corrosion.However,AAILs still have the disadvantages of high viscosity,complex synthesis steps and large industrial cost,which limit their industrial application.Therefore,AAILs blended with amine solution has attracted wide attention,which not only combines the advantages of high absorption rate of AAILs and large absorption capacity of amine,but also effectively reduces the vapor pressure and the equipment corrosion.In this thesis,[N₁₁₁₁][Gly]and[Bmim][Lys]are used as accelerators,MDEA is used as the absorbent.The CO₂ desorption performance of MDEA-AAILs aqueous solution was explored,and the influence of AAILs type and AAILs concentration on CO₂ desorption was investigated.Fourier transform infrared spectroscopy（FT-IR）and nuclear magnetic resonance carbon spectroscopy(¹³C NMR)were used to analyze the chemical structure changes and CO₂ desorption mechanism.The results show that the introduction of AAILs can not only improve the absorption rate and the absorption capacity,but also significantly enhance the regeneration performance.It is found that absorbents composed of30wt%MDEA-and 10wt%[Bmim][Lys]and 30wt%MDEA-and 5wt%[N₁₁₁₁][Gly]have excellent desorption performance,with a highest regeneration efficiency of 83.14%.On the basis of the desorption experiment,the corrosion characteristics of 20#carbon steel in the aforementioned carbonated absorbents were studied,and the influence of temperature,AAILs concentration,AAILs types,CO₂ loading and p H value on the corrosion rate were investigated.At the same time,scanning electron microscopy（SEM）and energy dispersive X-ray spectroscopy（EDS）were used to observe the corrosion morphology of carbon steel surface and analyze the corrosion mechanism.The results show that the presence of corrosion-inhibiting heteroatoms（such as N）has a significant inhibitory effect on the corrosion rate,and the siderite layer formed on the surface of carbon steel may also decrease the corrosion rate.