醇胺溶液CO2吸收过程反应机制OA

[Objective]Presently,CO2 capture technology based on the ethanolamine solutions suffers from drawbacks such as high energy consumption and elevated costs.A primary method to address these challenges is to construct blen-ded amine solutions by synergistically integrating the absorption and desorption advantages of different types of ethano-lamines.Hydroxyethyl ethylenediamine(AEEA)and N-methyldiethanolamine(MDEA)represent two major commonly used absorbents,and their blending necessitates an accurate understanding of their CO2 absorption patterns,including CO2 loading capacity,the ion-concentration distribution patterns of reaction products,and reaction orders.Currently,their absorption mechanisms remain poorly understood,and there is a lack of relevant reaction parameters,jointly under-mining the prediction accuracy of process models.[Methods]By investigating the CO2 absorption processes of AEEA and MDEA solutions,this study clarified the reaction mechanisms of both solutions.Furthermore,it established ion con-centration distribution models of the reaction products based on pH values,determined the reaction orders through re-gression analysis,and developed the reaction rate models of both solutions.[Results and Conclusions]The results in-dicate that,under the same concentration,the AEEA solution exhibited higher CO2 absorption capacity and rates com-pared to the MDEA solution.The AEEA solution presented a two-stage CO2 absorption process,with reaction orders ap-proaching 2.Initially,the CO2 absorption process in the AEEA solution was controlled by the formation of zwitterionic intermediates(R1R2NH+COO-)from AEEA-CO2 reactions.In the late stage,this process was jointly governed by mass transfer and reactions.In contrast,the CO2 absorption in the MDEA solution was identified as a base-catalyzed hydra-tion process,with the reaction rate showing a linear correlation with the MDEA concentration and the reaction order de-termined at 1.The novel insights and models of this study provide theoretical guidance for the optimization of the con-centration,retention time,and circulation rate of solvents,along with column design,in carbon capture technique.