[Objective] Aiming at the phenomena of poor purification efficiency of Heat-Stable Salts (HSS) and high amine loss caused by CO2 loading in lean amine solutions during the ion exchange purification process of flue gas decarbonization amine liquid, this study investigates the influence mechanism of CO2 loading on HSS removal and amine loss. The primary goal is to provide comprehensive theoretical and experimental support for the optimization of the amine liquid purification process using the ion exchange method. 

[Methods] Taking the simulated amine solution containing heat-stable salts (HSS) and specific CO2 loadings as the research object, both static and dynamic ion exchange experiments were conducted to thoroughly explore the specific impacts of CO2 loading on the purification process. In conjunction with comprehensive mass balance calculations, the migration patterns of amine species and the underlying loss mechanisms behind them were systematically analyzed. Furthermore, a mathematical model was constructed to precisely quantify the relationship between the amount of amine loss and the amount of HSS removal. This model was subsequently utilized to compare the loss -reduction performance 2 brought by various optimized processes under different operational conditions. 

[Results] Static ion exchange experiments indicated that an increase in CO2 loading significantly reduces the effectiveness of the resin in removing HSS from the solution. Dynamic ion exchange experiments further revealed that the resin exhibits no significant adsorption selectivity between CO2-loaded anions and HSS anions, leading to competitive adsorption. Following the amine liquid purification process, while the HSS mass fraction was successfully reduced from 5 % to 1.4%, a concurrent amine loss of 2.90% by mass fraction was generated. Detailed analysis showed that 96.72% of this total loss originated from the adsorption loss of carbamate species onto the resin. The constructed model for quantifying the relationship between amine loss and HSS removal was plotted into analytical charts, enabling the objectives of horizontal process comparison and trend prediction. Three optimization processes —namely pre -alkalization transformation, secondary desorption, and internal circulation —were proposed and compared with t he traditional process through model simulation, and the results demonstrated that all three optimized processes could achieve loss reduction compared to the traditional process. 

[Conclusion] High CO2 loading in flue gas decarbonization amine liquid is the core factor restricting the effectiveness of the ion exchange purification method. The competitive adsorption between CO2 loading anions and HSS anions inevitably reduces purification efficiency. Crucially, the adsorption of carbamate from the CO2 loading anions onto the resin is the direct cause of significant amine loss. These findings underscore the necessity of managing CO2 levels prior to ion exchange to ensure process sustainability.