Selection of blended absorbents for CO₂ capture from flue gas: CO₂ solubility, corrosion and absorption rate

In the present study, trisodium phosphate (TSP) was used as a base solvent for CO₂ capture, and five amines, including 2-((2-aminoethyl)amino)ethanol (AEEA), methyldiethanolamine (MDEA), piperazine (PZ), potassium sarcosinate (K-Sar) and potassium lysinate (K-Lys) were studied as potential additives to improve the absorption performance. In order to investigate and compare the performance of these blended solutions, the corrosion rate, the absorption rate and CO₂ solubility were measured at a total concentration of 2.5 kmol/m³ and partial pressure of CO₂ ranging from 5 to 50 kPa at 313.15 K, and were compared with monoethanolamine (MEA). The experimental results revealed that PZ as an additive in trisodium phosphate has the highest absorption rate, but the K-Lys + TSP blend solution has the highest loading capacity compared to other additives. In contrast, MDEA showed the lowest effect on the corrosion rate, CO₂ solubility and absorption rate of trisodium phosphate and PZ as the additive has the highest corrosion rate. Furthermore, it was found that these blend solutions have a better performance than pure MEA. In conclusion, K-Lys is a promising additive for trisodium phosphate to apply in the separation of CO₂ from gas streams.