Research On Degradation Of Blended Amine Solution For CO₂ Chemical Absorption Technology

The chemical absorption method is a widely used post-combustion capture technology,but there is still a problem of high operating costs.The development of a new type of low energy consumption and low degradation absorbent is the key to solving this problem.In this paper,ethanolamine（MEA）+2-amino-2-methyl-1-propanol（AMP）aqueous solution（hereinafter referred to as MAH）and AMP+anhydrous piperazine（PZ）aqueous solution（hereinafter referred to as APH）have high CO₂ absorption The blended amine absorbents with high volume,high regeneration rate and low desorption energy consumption are the research objects,which are divided into two parts:oxidative degradation and thermal degradation.Through forced degradation experiments,the influencing factors of the degradation behavior of blended amine absorbents are studied,and the complex degradation process is explored.The key reaction mechanism of the amine,and screening of inhibitors suitable for new blended amine absorbents.This article first studied the effects of different absorbent components（MEA,AMP,PZ）,thermal degradation temperature（120℃-140℃）,and CO₂ load（0-2mol/L）on the thermal degradation behavior of blended amines.The results showed that the interaction between MAH components inhibited the degradation of MEA and AMP;the interaction between APH components promoted the degradation of PZ and inhibited the degradation of AMP.Different blended amine absorbents have the lowest temperature required for thermal degradation.After this temperature,the higher the temperature,the faster the degradation rate.When the temperature increases from 120°C to 140°C,the total degradation rate of components MEA,AMP,and PZ will increase 383%,252%,73.3%.The components MEA and AMP have the lowest CO₂ load required for degradation,and they decrease with the increase of temperature.After this load is exceeded,the degradation obviously occurs,and as the load increases,the degradation rate becomes faster.During the thermal degradation of MAH,there is no cross-reaction between MEA and AMP.MEA mainly undergoes carbamate polymerization reaction,with the accumulation of degradation products,the degradation process intensifies.The sterically hindered structure of AMP,the formed carbamate is not stable,and it is difficult for subsequent addition polymerization reactions to occur;during the thermal degradation of APH,the components AMP and PZ have cross-reactions.The carbamate polymerization reaction and transalkylation reaction of AMP occur first in the degradation process,and the PZ degradation process reacts with AMP and its degradation products.Therefore,the presence of AMP promotes the thermal degradation reaction of PZ.For the oxidative degradation of blended amine absorbents,this paper studies the interaction between components and the influence of Fe²⁺content on the degradation process,and screens suitable inhibitors.The results showed that the interaction between MAH components inhibited the degradation of MEA and promoted the degradation of AMP;the interaction between APH components promoted the degradation of AMP and PZ.Fe²⁺has a significant catalytic effect on the oxidative degradation of each component of the blended amine absorbent.For MAH,the addition of Fe2+increases the total degradation rate of MEA by 80.3%and the total degradation rate of AMP by 81.7%;for APH,the addition of Fe²⁺makes the total degradation of AMP The rate increased by 181%,and the total degradation rate of PZ increased by37.3%.The Fe²⁺content is different,there is a slight difference in the degradation process of each group,but the total degradation rate of the final component is similar.During the oxidative degradation of MAH,there is a cross-reaction between MEA and AMP.MEA is degraded first,and the degradation products（glycine,glycolic acid,etc.）will continue to react with AMP and MEA to accelerate the degradation reaction;in the process of APH oxidative degradation,no substances formed by the reaction between AMP and PZ are detected in the degradation products.However,as a good nucleophile,PZ can react with the degradation products of AMP（such as formic acid and acetone）during the degradation process,resulting in an increase in the degradation rate of PZ when AMP and PZ are blended.Finally,by measuring the degradation rate of the absorbent,the amount of CO₂ carried,and the alkalinity of the solution,the metal trapping agent EDTA was selected as the inhibitor for MAH and APH.