Synthesis Of Amino Acids-based Deep Eutectic Solvent And Its Performance For CO₂ Capture

The CO₂ has made a great contribution to global warming.The realization of green and efficient CO₂ capture is of great practical significance for improving ecological environment.Alcohol/amine solvents are mostly used for CO₂ capture in industry.However,there are still some problems need to be resolved,such as large loss,difficult regeneration and ammonia/amine escape.In this study,three kinds of natural amino acid deep eutectic solvents?DES?were prepared to improve the reproducibility and ecological toxicity of CO₂ capture solvent.The DES were analyzed and investigated for their behaviors in CO₂ capture.Additionally,an insight into the reaction mechanism was investigated.The main research contents and results were as followsThe DES were synthesized using L-arginine?L-Arg?,L-lysine?L-Lys?,ethylene glycol?EG?and glycerol?Gly?.There were three kinds of DES were prepared successfully,named L-Arg/Gly?L-Lys/Gly and L-Arg/EG,respectively.The optimum raw material proportion,synthetic temperature,pressure,and time were all studied.The physical properties of DES were characterized,including conductivity,density,viscosity,moisture content,thermal stability,pH,and polarity.In the application of CO₂ capture with Amino Acids-based DES,it was shown that the capture capacity of CO₂was up to 0.81molCO₂/molDES,under the conditions of CO₂flow 200mL/min,n_L-Arg/n_EG 1?1,with L-Arg/EG as capture solvent.Moreover,after 5cycles of absorption/desorption of CO₂,the capture capacity of L-Arg/EG was not significantly reduced.The response surface method was used to investigate the interaction effects of gas velocity,temperature,the amount of capture and capture rate.It was found that low temperature and low gas velocity were beneficial to capture capacity,but high temperature was beneficial to capture rate.The main factor affecting the efficiency of capture CO₂ by amino acid-based DES is mass-transfer resistance.Based on this,DES hydrates were synthesized further.It was shown that DES hydrates had significant advantages in kinetics for its low viscosity,therefore,greatly increased the capture capacity and capture rate.Besides the process,an insight study of the mechanism of CO₂ capture by DES was also carried out.It was found that hydrogen-bond network structure played an important role in the process of CO₂ capture,and the electron transfer reaction mechanism between DES and CO₂ was proposed.Amino acids and polyols formed a hydrogen bond network by intermolecular hydrogen bonding to form DES.DES captures CO₂ by changing its own hydrogen bond network.The weaker the intermolecular hydrogen bond is,the better it is to capture CO2.